[PATCH] drm/amd/display: update bios scratch when setting backlight

[Harry Wentland]

On 2021-11-24 11:36, Alex Deucher wrote:
> Update the bios scratch register when updating the backlight
> level.  Some platforms apparently read this scratch register
> and do additional operations in their hotkey handlers.
> 
> Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1518
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>

Maybe dce_driver_set_backlight should handle this but doing this
in amdgpu also works. I don't know if I have a preference either
way.

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

Harry

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c      | 12 ++++++++++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h      |  2 ++
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  4 ++++
>  3 files changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
> index 96b7bb13a2dd..12a6b1c99c93 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
> @@ -1569,6 +1569,18 @@ void amdgpu_atombios_scratch_regs_engine_hung(struct amdgpu_device *adev,
>  	WREG32(adev->bios_scratch_reg_offset + 3, tmp);
>  }
>  
> +void amdgpu_atombios_scratch_regs_set_backlight_level(struct amdgpu_device *adev,
> +						      u32 backlight_level)
> +{
> +	u32 tmp = RREG32(adev->bios_scratch_reg_offset + 2);
> +
> +	tmp &= ~ATOM_S2_CURRENT_BL_LEVEL_MASK;
> +	tmp |= (backlight_level << ATOM_S2_CURRENT_BL_LEVEL_SHIFT) &
> +		ATOM_S2_CURRENT_BL_LEVEL_MASK;
> +
> +	WREG32(adev->bios_scratch_reg_offset + 2, tmp);
> +}
> +
>  bool amdgpu_atombios_scratch_need_asic_init(struct amdgpu_device *adev)
>  {
>  	u32 tmp = RREG32(adev->bios_scratch_reg_offset + 7);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h
> index 8cc0222dba19..27e74b1fc260 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h
> @@ -185,6 +185,8 @@ bool amdgpu_atombios_has_gpu_virtualization_table(struct amdgpu_device *adev);
>  void amdgpu_atombios_scratch_regs_lock(struct amdgpu_device *adev, bool lock);
>  void amdgpu_atombios_scratch_regs_engine_hung(struct amdgpu_device *adev,
>  					      bool hung);
> +void amdgpu_atombios_scratch_regs_set_backlight_level(struct amdgpu_device *adev,
> +						      u32 backlight_level);
>  bool amdgpu_atombios_scratch_need_asic_init(struct amdgpu_device *adev);
>  
>  void amdgpu_atombios_copy_swap(u8 *dst, u8 *src, u8 num_bytes, bool to_le);
> 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 40a4269770fa..05e4a0952a2b 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -51,6 +51,7 @@
>  #include <drm/drm_hdcp.h>
>  #endif
>  #include "amdgpu_pm.h"
> +#include "amdgpu_atombios.h"
>  
>  #include "amd_shared.h"
>  #include "amdgpu_dm_irq.h"
> @@ -3918,6 +3919,9 @@ static int amdgpu_dm_backlight_set_level(struct amdgpu_display_manager *dm,
>  	caps = dm->backlight_caps[bl_idx];
>  
>  	dm->brightness[bl_idx] = user_brightness;
> +	/* update scratch register */
> +	if (bl_idx == 0)
> +		amdgpu_atombios_scratch_regs_set_backlight_level(dm->adev, dm->brightness[bl_idx]);
>  	brightness = convert_brightness_from_user(&caps, dm->brightness[bl_idx]);
>  	link = (struct dc_link *)dm->backlight_link[bl_idx];
>  
>