Re: [Intel-gfx] [PATCH v3 4/9] PCI/VGA: Improve the default VGA device selection

[suijingfeng]

Hi,

Thanks for you noticed my change.


On 2023/7/20 03:32, Bjorn Helgaas wrote:
@@ -1509,13 +1543,24 @@ static int pci_notify(struct notifier_block *nb, 
unsigned long action,
         * cases of hotplugable vga cards.
         */
  
-	if (action == BUS_NOTIFY_ADD_DEVICE)
+       switch (action) {
+       case BUS_NOTIFY_ADD_DEVICE:
                notify = vga_arbiter_add_pci_device(pdev);
-       else if (action == BUS_NOTIFY_DEL_DEVICE)
+               if (notify)
+                       vga_arbiter_notify_clients();
+               break;
+       case BUS_NOTIFY_DEL_DEVICE:
                notify = vga_arbiter_del_pci_device(pdev);
+               if (notify)
+                       vga_arbiter_notify_clients();
+               break;
+       case BUS_NOTIFY_BOUND_DRIVER:
+               vga_arbiter_do_arbitration(pdev);
+               break;
+       default:
+               break;
+       }
Changing from if/else to switch makes the patch bigger than necessary
for no real benefit and obscures what is really changing.

Actually, the logic become more clear after this patch applied.

```

    switch (action) {
    case BUS_NOTIFY_ADD_DEVICE:
        notify = vga_arbiter_add_pci_device(pdev);
        if (notify)
            vga_arbiter_notify_clients();
        break;
    case BUS_NOTIFY_DEL_DEVICE:
        notify = vga_arbiter_del_pci_device(pdev);
        if (notify)
            vga_arbiter_notify_clients();
        break;
    case BUS_NOTIFY_BOUND_DRIVER:
        vga_arbiter_do_arbitration(pdev);
        break;
    default:
        break;
    }

```


Because we only need call vga_arbiter_notify_clients() when action == 
BUS_NOTIFY_ADD_DEVICE or action == BUS_NOTIFY_DEL_DEVICE,

But *NOT* when the action equals to  BUS_NOTIFY_BOUND_DRIVER.