473 lines
13 KiB
C
Executable file
473 lines
13 KiB
C
Executable file
// SPDX-License-Identifier: GPL-2.0
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/*
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* Setup routines for AGP 3.5 compliant bridges.
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*/
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#include <linux/list.h>
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#include <linux/pci.h>
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#include <linux/agp_backend.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include "agp.h"
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/* Generic AGP 3.5 enabling routines */
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struct agp_3_5_dev {
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struct list_head list;
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u8 capndx;
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u32 maxbw;
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struct pci_dev *dev;
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};
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static void agp_3_5_dev_list_insert(struct list_head *head, struct list_head *new)
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{
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struct agp_3_5_dev *cur, *n = list_entry(new, struct agp_3_5_dev, list);
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struct list_head *pos;
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list_for_each(pos, head) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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if (cur->maxbw > n->maxbw)
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break;
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}
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list_add_tail(new, pos);
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}
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static void agp_3_5_dev_list_sort(struct agp_3_5_dev *list, unsigned int ndevs)
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{
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struct agp_3_5_dev *cur;
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struct pci_dev *dev;
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struct list_head *pos, *tmp, *head = &list->list, *start = head->next;
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u32 nistat;
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INIT_LIST_HEAD(head);
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for (pos=start; pos!=head; ) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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dev = cur->dev;
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pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &nistat);
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cur->maxbw = (nistat >> 16) & 0xff;
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tmp = pos;
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pos = pos->next;
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agp_3_5_dev_list_insert(head, tmp);
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}
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}
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/*
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* Initialize all isochronous transfer parameters for an AGP 3.0
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* node (i.e. a host bridge in combination with the adapters
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* lying behind it...)
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*/
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static int agp_3_5_isochronous_node_enable(struct agp_bridge_data *bridge,
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struct agp_3_5_dev *dev_list, unsigned int ndevs)
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{
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/*
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* Convenience structure to make the calculations clearer
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* here. The field names come straight from the AGP 3.0 spec.
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*/
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struct isoch_data {
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u32 maxbw;
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u32 n;
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u32 y;
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u32 l;
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u32 rq;
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struct agp_3_5_dev *dev;
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};
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struct pci_dev *td = bridge->dev, *dev;
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struct list_head *head = &dev_list->list, *pos;
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struct agp_3_5_dev *cur;
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struct isoch_data *master, target;
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unsigned int cdev = 0;
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u32 mnistat, tnistat, tstatus, mcmd;
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u16 tnicmd, mnicmd;
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u8 mcapndx;
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u32 tot_bw = 0, tot_n = 0, tot_rq = 0, y_max, rq_isoch, rq_async;
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u32 step, rem, rem_isoch, rem_async;
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int ret = 0;
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/*
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* We'll work with an array of isoch_data's (one for each
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* device in dev_list) throughout this function.
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*/
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master = kmalloc_array(ndevs, sizeof(*master), GFP_KERNEL);
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if (master == NULL) {
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ret = -ENOMEM;
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goto get_out;
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}
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/*
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* Sort the device list by maxbw. We need to do this because the
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* spec suggests that the devices with the smallest requirements
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* have their resources allocated first, with all remaining resources
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* falling to the device with the largest requirement.
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*
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* We don't exactly do this, we divide target resources by ndevs
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* and split them amongst the AGP 3.0 devices. The remainder of such
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* division operations are dropped on the last device, sort of like
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* the spec mentions it should be done.
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*
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* We can't do this sort when we initially construct the dev_list
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* because we don't know until this function whether isochronous
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* transfers are enabled and consequently whether maxbw will mean
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* anything.
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*/
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agp_3_5_dev_list_sort(dev_list, ndevs);
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pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
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pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
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/* Extract power-on defaults from the target */
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target.maxbw = (tnistat >> 16) & 0xff;
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target.n = (tnistat >> 8) & 0xff;
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target.y = (tnistat >> 6) & 0x3;
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target.l = (tnistat >> 3) & 0x7;
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target.rq = (tstatus >> 24) & 0xff;
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y_max = target.y;
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/*
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* Extract power-on defaults for each device in dev_list. Along
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* the way, calculate the total isochronous bandwidth required
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* by these devices and the largest requested payload size.
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*/
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list_for_each(pos, head) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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dev = cur->dev;
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mcapndx = cur->capndx;
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pci_read_config_dword(dev, cur->capndx+AGPNISTAT, &mnistat);
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master[cdev].maxbw = (mnistat >> 16) & 0xff;
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master[cdev].n = (mnistat >> 8) & 0xff;
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master[cdev].y = (mnistat >> 6) & 0x3;
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master[cdev].dev = cur;
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tot_bw += master[cdev].maxbw;
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y_max = max(y_max, master[cdev].y);
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cdev++;
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}
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/* Check if this configuration has any chance of working */
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if (tot_bw > target.maxbw) {
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dev_err(&td->dev, "isochronous bandwidth required "
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"by AGP 3.0 devices exceeds that which is supported by "
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"the AGP 3.0 bridge!\n");
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ret = -ENODEV;
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goto free_and_exit;
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}
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target.y = y_max;
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/*
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* Write the calculated payload size into the target's NICMD
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* register. Doing this directly effects the ISOCH_N value
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* in the target's NISTAT register, so we need to do this now
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* to get an accurate value for ISOCH_N later.
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*/
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pci_read_config_word(td, bridge->capndx+AGPNICMD, &tnicmd);
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tnicmd &= ~(0x3 << 6);
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tnicmd |= target.y << 6;
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pci_write_config_word(td, bridge->capndx+AGPNICMD, tnicmd);
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/* Reread the target's ISOCH_N */
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pci_read_config_dword(td, bridge->capndx+AGPNISTAT, &tnistat);
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target.n = (tnistat >> 8) & 0xff;
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/* Calculate the minimum ISOCH_N needed by each master */
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for (cdev=0; cdev<ndevs; cdev++) {
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master[cdev].y = target.y;
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master[cdev].n = master[cdev].maxbw / (master[cdev].y + 1);
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tot_n += master[cdev].n;
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}
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/* Exit if the minimal ISOCH_N allocation among the masters is more
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* than the target can handle. */
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if (tot_n > target.n) {
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dev_err(&td->dev, "number of isochronous "
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"transactions per period required by AGP 3.0 devices "
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"exceeds that which is supported by the AGP 3.0 "
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"bridge!\n");
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ret = -ENODEV;
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goto free_and_exit;
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}
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/* Calculate left over ISOCH_N capability in the target. We'll give
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* this to the hungriest device (as per the spec) */
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rem = target.n - tot_n;
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/*
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* Calculate the minimum isochronous RQ depth needed by each master.
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* Along the way, distribute the extra ISOCH_N capability calculated
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* above.
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*/
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for (cdev=0; cdev<ndevs; cdev++) {
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/*
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* This is a little subtle. If ISOCH_Y > 64B, then ISOCH_Y
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* byte isochronous writes will be broken into 64B pieces.
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* This means we need to budget more RQ depth to account for
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* these kind of writes (each isochronous write is actually
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* many writes on the AGP bus).
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*/
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master[cdev].rq = master[cdev].n;
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if (master[cdev].y > 0x1)
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master[cdev].rq *= (1 << (master[cdev].y - 1));
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tot_rq += master[cdev].rq;
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}
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master[ndevs-1].n += rem;
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/* Figure the number of isochronous and asynchronous RQ slots the
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* target is providing. */
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rq_isoch = (target.y > 0x1) ? target.n * (1 << (target.y - 1)) : target.n;
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rq_async = target.rq - rq_isoch;
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/* Exit if the minimal RQ needs of the masters exceeds what the target
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* can provide. */
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if (tot_rq > rq_isoch) {
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dev_err(&td->dev, "number of request queue slots "
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"required by the isochronous bandwidth requested by "
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"AGP 3.0 devices exceeds the number provided by the "
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"AGP 3.0 bridge!\n");
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ret = -ENODEV;
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goto free_and_exit;
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}
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/* Calculate asynchronous RQ capability in the target (per master) as
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* well as the total number of leftover isochronous RQ slots. */
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step = rq_async / ndevs;
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rem_async = step + (rq_async % ndevs);
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rem_isoch = rq_isoch - tot_rq;
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/* Distribute the extra RQ slots calculated above and write our
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* isochronous settings out to the actual devices. */
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for (cdev=0; cdev<ndevs; cdev++) {
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cur = master[cdev].dev;
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dev = cur->dev;
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mcapndx = cur->capndx;
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master[cdev].rq += (cdev == ndevs - 1)
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? (rem_async + rem_isoch) : step;
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pci_read_config_word(dev, cur->capndx+AGPNICMD, &mnicmd);
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pci_read_config_dword(dev, cur->capndx+AGPCMD, &mcmd);
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mnicmd &= ~(0xff << 8);
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mnicmd &= ~(0x3 << 6);
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mcmd &= ~(0xff << 24);
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mnicmd |= master[cdev].n << 8;
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mnicmd |= master[cdev].y << 6;
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mcmd |= master[cdev].rq << 24;
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pci_write_config_dword(dev, cur->capndx+AGPCMD, mcmd);
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pci_write_config_word(dev, cur->capndx+AGPNICMD, mnicmd);
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}
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free_and_exit:
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kfree(master);
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get_out:
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return ret;
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}
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/*
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* This function basically allocates request queue slots among the
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* AGP 3.0 systems in nonisochronous nodes. The algorithm is
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* pretty stupid, divide the total number of RQ slots provided by the
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* target by ndevs. Distribute this many slots to each AGP 3.0 device,
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* giving any left over slots to the last device in dev_list.
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*/
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static void agp_3_5_nonisochronous_node_enable(struct agp_bridge_data *bridge,
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struct agp_3_5_dev *dev_list, unsigned int ndevs)
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{
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struct agp_3_5_dev *cur;
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struct list_head *head = &dev_list->list, *pos;
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u32 tstatus, mcmd;
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u32 trq, mrq, rem;
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unsigned int cdev = 0;
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pci_read_config_dword(bridge->dev, bridge->capndx+AGPSTAT, &tstatus);
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trq = (tstatus >> 24) & 0xff;
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mrq = trq / ndevs;
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rem = mrq + (trq % ndevs);
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for (pos=head->next; cdev<ndevs; cdev++, pos=pos->next) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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pci_read_config_dword(cur->dev, cur->capndx+AGPCMD, &mcmd);
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mcmd &= ~(0xff << 24);
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mcmd |= ((cdev == ndevs - 1) ? rem : mrq) << 24;
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pci_write_config_dword(cur->dev, cur->capndx+AGPCMD, mcmd);
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}
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}
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/*
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* Fully configure and enable an AGP 3.0 host bridge and all the devices
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* lying behind it.
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*/
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int agp_3_5_enable(struct agp_bridge_data *bridge)
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{
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struct pci_dev *td = bridge->dev, *dev = NULL;
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u8 mcapndx;
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u32 isoch, arqsz;
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u32 tstatus, mstatus, ncapid;
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u32 mmajor;
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u16 mpstat;
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struct agp_3_5_dev *dev_list, *cur;
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struct list_head *head, *pos;
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unsigned int ndevs = 0;
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int ret = 0;
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/* Extract some power-on defaults from the target */
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pci_read_config_dword(td, bridge->capndx+AGPSTAT, &tstatus);
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isoch = (tstatus >> 17) & 0x1;
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if (isoch == 0) /* isoch xfers not available, bail out. */
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return -ENODEV;
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arqsz = (tstatus >> 13) & 0x7;
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/*
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* Allocate a head for our AGP 3.5 device list
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* (multiple AGP v3 devices are allowed behind a single bridge).
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*/
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if ((dev_list = kmalloc(sizeof(*dev_list), GFP_KERNEL)) == NULL) {
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ret = -ENOMEM;
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goto get_out;
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}
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head = &dev_list->list;
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INIT_LIST_HEAD(head);
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/* Find all AGP devices, and add them to dev_list. */
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for_each_pci_dev(dev) {
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mcapndx = pci_find_capability(dev, PCI_CAP_ID_AGP);
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if (mcapndx == 0)
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continue;
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switch ((dev->class >>8) & 0xff00) {
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case 0x0600: /* Bridge */
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/* Skip bridges. We should call this function for each one. */
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continue;
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case 0x0001: /* Unclassified device */
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/* Don't know what this is, but log it for investigation. */
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if (mcapndx != 0) {
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dev_info(&td->dev, "wacky, found unclassified AGP device %s [%04x/%04x]\n",
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pci_name(dev),
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dev->vendor, dev->device);
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}
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continue;
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case 0x0300: /* Display controller */
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case 0x0400: /* Multimedia controller */
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if ((cur = kmalloc(sizeof(*cur), GFP_KERNEL)) == NULL) {
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ret = -ENOMEM;
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goto free_and_exit;
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}
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cur->dev = dev;
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pos = &cur->list;
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list_add(pos, head);
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ndevs++;
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continue;
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default:
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continue;
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}
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}
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/*
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* Take an initial pass through the devices lying behind our host
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* bridge. Make sure each one is actually an AGP 3.0 device, otherwise
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* exit with an error message. Along the way store the AGP 3.0
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* cap_ptr for each device
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*/
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list_for_each(pos, head) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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dev = cur->dev;
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pci_read_config_word(dev, PCI_STATUS, &mpstat);
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if ((mpstat & PCI_STATUS_CAP_LIST) == 0)
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continue;
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pci_read_config_byte(dev, PCI_CAPABILITY_LIST, &mcapndx);
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if (mcapndx != 0) {
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do {
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pci_read_config_dword(dev, mcapndx, &ncapid);
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if ((ncapid & 0xff) != 2)
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mcapndx = (ncapid >> 8) & 0xff;
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}
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while (((ncapid & 0xff) != 2) && (mcapndx != 0));
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}
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if (mcapndx == 0) {
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dev_err(&td->dev, "woah! Non-AGP device %s on "
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"secondary bus of AGP 3.5 bridge!\n",
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pci_name(dev));
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ret = -ENODEV;
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goto free_and_exit;
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}
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mmajor = (ncapid >> AGP_MAJOR_VERSION_SHIFT) & 0xf;
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if (mmajor < 3) {
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dev_err(&td->dev, "woah! AGP 2.0 device %s on "
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"secondary bus of AGP 3.5 bridge operating "
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"with AGP 3.0 electricals!\n", pci_name(dev));
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ret = -ENODEV;
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goto free_and_exit;
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}
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cur->capndx = mcapndx;
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pci_read_config_dword(dev, cur->capndx+AGPSTAT, &mstatus);
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if (((mstatus >> 3) & 0x1) == 0) {
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dev_err(&td->dev, "woah! AGP 3.x device %s not "
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"operating in AGP 3.x mode on secondary bus "
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"of AGP 3.5 bridge operating with AGP 3.0 "
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"electricals!\n", pci_name(dev));
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ret = -ENODEV;
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goto free_and_exit;
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}
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}
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/*
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* Call functions to divide target resources amongst the AGP 3.0
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* masters. This process is dramatically different depending on
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* whether isochronous transfers are supported.
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*/
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if (isoch) {
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ret = agp_3_5_isochronous_node_enable(bridge, dev_list, ndevs);
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if (ret) {
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dev_info(&td->dev, "something bad happened setting "
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"up isochronous xfers; falling back to "
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"non-isochronous xfer mode\n");
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} else {
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goto free_and_exit;
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}
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}
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agp_3_5_nonisochronous_node_enable(bridge, dev_list, ndevs);
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free_and_exit:
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/* Be sure to free the dev_list */
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for (pos=head->next; pos!=head; ) {
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cur = list_entry(pos, struct agp_3_5_dev, list);
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pos = pos->next;
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kfree(cur);
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}
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kfree(dev_list);
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get_out:
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return ret;
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}
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