APPLIED [OEM-5.10] Re: [SRU] [H/Unstable/OEM-5.10] [PATCH 0/1] Select correct boot VGA when BIOS doesn't do it properly

[Timo Aaltonen]

On 21.5.2021 16.07, Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/1929217
> 
> [Impact]
> On HP EliteDesk 805 G7 desktop, when a add-in discrete GFX card is
> present but the display is connected to integrated GPU, BIOS cannot find
> the correct boot VGA. Hence, wrong OpenGL/Vulkan library is used, makes
> the desktop environment very laggy.
> 
> [Fix]
> The current heuristic picks the fallback VGA device with lowest PCI
> device number. Based on the current heuristic, also check for ACPI video
> device which should be the integrated VGA device.
> 
> [Test]
> Check if the integrated GPU is the boot VGA:
> $ cat /sys/bus/pci/devices/0000\:08\:00.0/boot_vga
> 0
> 
> After applying the patch:
> $ cat /sys/bus/pci/devices/0000\:08\:00.0/boot_vga
> 1
> 
> [Where problems could occur]
> When there are multiple GPUs that are ACPI video devices, and BIOS
> failed to find a VGA to POST, the new heuristic introduces new behavior.
> 
> Since multiple ACPI video devices are on laptops, the EFI base should
> already be correct otherwise there's no POST. If that really happens the
> laptop is completely broken at first place.
> 
> Kai-Heng Feng (1):
>    vgaarb: Use ACPI HID name to find integrated GPU
> 
>   drivers/gpu/vga/vgaarb.c | 31 ++++++++++++++++++++++++++-----
>   1 file changed, 26 insertions(+), 5 deletions(-)
> 


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