Re: [PATCH] vgaarb: Use ACPI HID name to find integrated GPU

On Wed, May 19, 2021 at 9:57 AM Kai-Heng Feng kai.heng.feng@canonical.com 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@canonical.com

Reviewed-by: Alex Deucher alexander.deucher@amd.com

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