Re: [PATCH] drm/msm/mdp5: drop cursor pipe for msm8x76

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Missing `flush_hw_mask` update when converting to legacy LM cursor breaks cursor updates.
--

commit e1dbf3d7b78aa6bf44fff588ff9b069eceea7f6b
Author: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

drm/msm/mdp5: drop cursor pipe for msm8x76

This commit removes the separate cursor plane configuration for MSM8976/56
platforms. It drops the erroneously added pipe configuration to let the LM
block provide a legacy cursor instead.

> diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> index 7c91fc1915f39..389d74ff75163 100644
> --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> @@ -698,15 +698,6 @@ static const struct mdp5_cfg_hw msm8x76_config = {
>  			MDP_PIPE_CAP_SW_PIX_EXT	|
>  			0,
>  	},
> -	.pipe_cursor = {
> -		.count = 1,
> -		.base = { 0x440DC },
> -		.caps = MDP_PIPE_CAP_HFLIP	|
> -			MDP_PIPE_CAP_VFLIP	|
> -			MDP_PIPE_CAP_SW_PIX_EXT	|
> -			MDP_PIPE_CAP_CURSOR	|
> -			0,
> -	},

[Severity: High]
Since this drops the cursor pipe to rely on the legacy LM cursor, does the
ctl.flush_hw_mask in msm8x76_config also need to be updated?

Currently, flush_hw_mask is set to 0xffffffff for this platform. When
standalone cursor updates use MDP5_CTL_FLUSH_CURSOR_0, fix_sw_flush() in
mdp5_ctl.c translates this to an LM flush for legacy cursors. However, this
fallback is only triggered if BIT_NEEDS_SW_FIX() determines the cursor flush
bit is excluded from the platform's flush_hw_mask.

Because the cursor bit is still included in the 0xffffffff mask, the
software fix evaluates to false. This prevents the LM from being flushed
and sends a hardware flush for a non-existent cursor block, which can
cause the cursor to lag or freeze during standalone updates.

Should flush_hw_mask be updated to exclude the cursor flush bits (for
example, 0xffffffff & ~MDP5_CTL_FLUSH_CURSOR_0)?

>  	.lm = {
>  		.count = 2,
>  		.base = { 0x44000, 0x45000 },

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260914-mdp5-fix-cursor-v1-1-9fba3ace6cb9@oss.qualcomm.com?part=1