Hi,
On 2023/6/13 11:01, Sui Jingfeng wrote:
From: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
Deal only with the VGA devcie(pdev->class == 0x0300), so replace the
pci_get_subsys() function with pci_get_class(). Filter the non-PCI display
device(pdev->class != 0x0300) out. There no need to process the non-display
PCI device.
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
---
drivers/pci/vgaarb.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
index c1bc6c983932..22a505e877dc 100644
--- a/drivers/pci/vgaarb.c
+++ b/drivers/pci/vgaarb.c
@@ -754,10 +754,6 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
struct pci_dev *bridge;
u16 cmd;
- /* Only deal with VGA class devices */
- if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
- return false;
-
Hi, here is probably a bug fixing.
For an example, nvidia render only GPU typically has 0x0380.
at its PCI class number, but render only GPU should not participate in
the arbitration.
As it shouldn't snoop the legacy fixed VGA address.
It(render only GPU) can not display anything.
But 0x0380 >> 8 = 0x03, the filter failed.
/* Allocate structure */
vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
if (vgadev == NULL) {
@@ -1500,7 +1496,9 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
struct pci_dev *pdev = to_pci_dev(dev);
bool notify = false;
- vgaarb_dbg(dev, "%s\n", __func__);
+ /* Only deal with VGA class devices */
+ if (pdev->class != PCI_CLASS_DISPLAY_VGA << 8)
+ return 0;
So here we only care 0x0300, my initial intent is to make an optimization,
nowadays sane display graphic card should all has 0x0300 as its PCI
class number, is this complete right?
```
#define PCI_BASE_CLASS_DISPLAY 0x03
#define PCI_CLASS_DISPLAY_VGA 0x0300
#define PCI_CLASS_DISPLAY_XGA 0x0301
#define PCI_CLASS_DISPLAY_3D 0x0302
#define PCI_CLASS_DISPLAY_OTHER 0x0380
```
Any ideas ?
/* For now we're only intereted in devices added and removed. I didn't
* test this thing here, so someone needs to double check for the
@@ -1510,6 +1508,8 @@ static int pci_notify(struct notifier_block *nb, unsigned long action,
else if (action == BUS_NOTIFY_DEL_DEVICE)
notify = vga_arbiter_del_pci_device(pdev);
+ vgaarb_dbg(dev, "%s: action = %lu\n", __func__, action);
+
if (notify)
vga_arbiter_notify_clients();
return 0;
@@ -1534,8 +1534,8 @@ static struct miscdevice vga_arb_device = {
static int __init vga_arb_device_init(void)
{
+ struct pci_dev *pdev = NULL;
int rc;
- struct pci_dev *pdev;
rc = misc_register(&vga_arb_device);
if (rc < 0)
@@ -1545,11 +1545,13 @@ static int __init vga_arb_device_init(void)
/* We add all PCI devices satisfying VGA class in the arbiter by
* default */
- pdev = NULL;
- while ((pdev =
- pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
- PCI_ANY_ID, pdev)) != NULL)
+ while (1) {
+ pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev);
+ if (!pdev)
+ break;
+
vga_arbiter_add_pci_device(pdev);
+ }
pr_info("loaded\n");
return rc;
--
Jingfeng
