[PATCH] drm/amdgpu/display: Only set vblank_disable_immediate when PSR is not enabled

[Harry Wentland]

On 2021-11-30 09:53, Nicholas Kazlauskas wrote:
> [Why]
> PSR currently relies on the kernel's delayed vblank on/off mechanism
> as an implicit bufferring mechanism to prevent excessive entry/exit.
> 
> Without this delay the user experience is impacted since it can take
> a few frames to enter/exit.
> 
> [How]
> Only allow vblank disable immediate for DC when psr is not supported.
> 
> Leave a TODO indicating that this support should be extended in the
> future to delay independent of the vblank interrupt.
> 
> Fixes: 3d1508b73ff1 ("drm/amdgpu/display: set vblank_disable_immediate for DC")
> 
> Cc: Harry Wentland <harry.wentland at amd.com>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>

Now I'm curious whether vblank_disable_immediate or PSR
save more power.

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

Harry

> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> 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 0747dc7922c2..d582d44c02ad 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1599,9 +1599,6 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
>  	adev_to_drm(adev)->mode_config.cursor_width = adev->dm.dc->caps.max_cursor_size;
>  	adev_to_drm(adev)->mode_config.cursor_height = adev->dm.dc->caps.max_cursor_size;
>  
> -	/* Disable vblank IRQs aggressively for power-saving */
> -	adev_to_drm(adev)->vblank_disable_immediate = true;
> -
>  	if (drm_vblank_init(adev_to_drm(adev), adev->dm.display_indexes_num)) {
>  		DRM_ERROR(
>  		"amdgpu: failed to initialize sw for display support.\n");
> @@ -4264,6 +4261,14 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
>  
>  	}
>  
> +	/*
> +	 * Disable vblank IRQs aggressively for power-saving.
> +	 *
> +	 * TODO: Fix vblank control helpers to delay PSR entry to allow this when PSR
> +	 * is also supported.
> +	 */
> +	adev_to_drm(adev)->vblank_disable_immediate = !psr_feature_enabled;
> +
>  	/* Software is initialized. Now we can register interrupt handlers. */
>  	switch (adev->asic_type) {
>  #if defined(CONFIG_DRM_AMD_DC_SI)
>