On Wed, May 19, 2021 at 9:57 AM Kai-Heng Feng
<kai.heng.feng@xxxxxxxxxxxxx> wrote:
>
> Commit 3d42f1ddc47a ("vgaarb: Keep adding VGA device in queue") assumes
> the first device is an integrated GPU. However, on AMD platforms an
> integrated GPU can have higher PCI device number than a discrete GPU.
>
> Integrated GPU on ACPI platform generally has _DOD and _DOS method, so
> use that as predicate to find integrated GPU. If the new strategy
> doesn't work, fallback to use the first device as boot VGA.
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
Unless there are any other comments, I'll apply it tomorrow.
Alex
> ---
> drivers/gpu/vga/vgaarb.c | 31 ++++++++++++++++++++++++++-----
> 1 file changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> index 5180c5687ee5..949fde433ea2 100644
> --- a/drivers/gpu/vga/vgaarb.c
> +++ b/drivers/gpu/vga/vgaarb.c
> @@ -50,6 +50,7 @@
> #include <linux/screen_info.h>
> #include <linux/vt.h>
> #include <linux/console.h>
> +#include <linux/acpi.h>
>
> #include <linux/uaccess.h>
>
> @@ -1450,9 +1451,23 @@ static struct miscdevice vga_arb_device = {
> MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> };
>
> +#if defined(CONFIG_ACPI)
> +static bool vga_arb_integrated_gpu(struct device *dev)
> +{
> + struct acpi_device *adev = ACPI_COMPANION(dev);
> +
> + return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
> +}
> +#else
> +static bool vga_arb_integrated_gpu(struct device *dev)
> +{
> + return false;
> +}
> +#endif
> +
> static void __init vga_arb_select_default_device(void)
> {
> - struct pci_dev *pdev;
> + struct pci_dev *pdev, *found = NULL;
> struct vga_device *vgadev;
>
> #if defined(CONFIG_X86) || defined(CONFIG_IA64)
> @@ -1505,20 +1520,26 @@ static void __init vga_arb_select_default_device(void)
> #endif
>
> if (!vga_default_device()) {
> - list_for_each_entry(vgadev, &vga_list, list) {
> + list_for_each_entry_reverse(vgadev, &vga_list, list) {
> struct device *dev = &vgadev->pdev->dev;
> u16 cmd;
>
> pdev = vgadev->pdev;
> pci_read_config_word(pdev, PCI_COMMAND, &cmd);
> if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
> - vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
> - vga_set_default_device(pdev);
> - break;
> + found = pdev;
> + if (vga_arb_integrated_gpu(dev))
> + break;
> }
> }
> }
>
> + if (found) {
> + vgaarb_info(&found->dev, "setting as boot device (VGA legacy resources not available)\n");
> + vga_set_default_device(found);
> + return;
> + }
> +
> if (!vga_default_device()) {
> vgadev = list_first_entry_or_null(&vga_list,
> struct vga_device, list);
> --
> 2.31.1
>
