Re: [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 
> Cc: Alex Deucher 
> Signed-off-by: Nicholas Kazlauskas 

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

Reviewed-by: Harry Wentland 

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)
> 

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

[Deucher, Alexander]

[Public]

Acked-by: Alex Deucher 

From: Nicholas Kazlauskas 
Sent: Tuesday, November 30, 2021 9:53 AM
To: amd-gfx@lists.freedesktop.org 
Cc: Kazlauskas, Nicholas ; Wentland, Harry 
; Deucher, Alexander 
Subject: [PATCH] drm/amdgpu/display: Only set vblank_disable_immediate when PSR 
is not enabled

[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 
Cc: Alex Deucher 
Signed-off-by: Nicholas Kazlauskas 
---
 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)
--
2.25.1