Re: [PATCH v3 2/3] drm/amd/display: Report to ACPI video if no panels were found

[Harry Wentland <harry.wentland@amd.com>]

On 12/8/22 11:42, Mario Limonciello wrote:
> On desktop APUs amdgpu doesn't create a native backlight device
> as no eDP panels are found.  However if the BIOS has reported
> backlight control methods in the ACPI tables then an acpi_video0
> backlight device will be made 8 seconds after boot.
> 
> This has manifested in a power slider on a number of desktop APUs
> ranging from Ryzen 5000 through Ryzen 7000 on various motherboard
> manufacturers. To avoid this, report to the acpi video detection
> that the system does not have any panel connected in the native
> driver.
> 
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783786
> Reported-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Reviewed-by: Harry Wentland <harry.wentland@amd.com>

Harry

> ---
> v2->v3:
>  * Add Hans' R-b
> v1->v2:
>  * No changes
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 512c32327eb1..b73f61ac5dd5 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -4371,6 +4371,10 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
>  		amdgpu_set_panel_orientation(&aconnector->base);
>  	}
>  
> +	/* If we didn't find a panel, notify the acpi video detection */
> +	if (dm->adev->flags & AMD_IS_APU && dm->num_of_edps == 0)
> +		acpi_video_report_nolcd();
> +
>  	/* Software is initialized. Now we can register interrupt handlers. */
>  	switch (adev->asic_type) {
>  #if defined(CONFIG_DRM_AMD_DC_SI)