回复: [PATCH] drm: komeda: Fix an issue related to normalized zpos

[Peng Hongchi/彭洪驰]

Hi, Liviu,

I'm sorry for my carelessness and thanks for your correction, the corrected patch is as follows. 
And we do have an extra patch to set layer_split, but this part of the code is owned by my colleague,
So that I cannot upload it, sorry about this.

Signed-off-by: hongchi.peng <hongchi.peng at siengine.com>
---
 drivers/gpu/drm/arm/display/komeda/komeda_kms.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
index fe46b0ebefea..ab769a0a4afa 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
@@ -160,6 +160,7 @@ static int komeda_crtc_normalize_zpos(struct drm_crtc *crtc,
 	struct drm_plane *plane;
 	struct list_head zorder_list;
 	int order = 0, err;
+	u32 slave_zpos;
 
 	DRM_DEBUG_ATOMIC("[CRTC:%d:%s] calculating normalized zpos values\n",
 			 crtc->base.id, crtc->name);
@@ -199,10 +200,13 @@ static int komeda_crtc_normalize_zpos(struct drm_crtc *crtc,
 				 plane_st->zpos, plane_st->normalized_zpos);
 
 		/* calculate max slave zorder */
-		if (has_bit(drm_plane_index(plane), kcrtc->slave_planes))
+		if (has_bit(drm_plane_index(plane), kcrtc->slave_planes)) {
+			slave_zpos = plane_st->normalized_zpos;
+			if (to_kplane_st(plane_st)->layer_split)
+				slave_zpos++;
 			kcrtc_st->max_slave_zorder =
-				max(plane_st->normalized_zpos,
-				    kcrtc_st->max_slave_zorder);
+				max(slave_zpos, kcrtc_st->max_slave_zorder);
+		}
 	}
 
 	crtc_st->zpos_changed = true;
--
2.34.1

Best Regards,
Hongchi Peng

-----邮件原件-----
发件人: Liviu Dudau <liviu.dudau at arm.com> 
发送时间: 2024年8月22日 22:05
收件人: Peng Hongchi/彭洪驰 <hongchi.peng at siengine.com>
抄送: maarten.lankhorst at linux.intel.com; mripard at kernel.org; tzimmermann at suse.de; airlied at gmail.com; daniel at ffwll.ch; dri-devel at lists.freedesktop.org
主题: Re: [PATCH] drm: komeda: Fix an issue related to normalized zpos

Hi Hongchi,

On Wed, Aug 21, 2024 at 04:56:13PM +0800, hongchi.peng wrote:
> We use komeda_crtc_normalize_zpos to normalize zpos of affected planes 
> to their blending zorder in CU. If there's only one slave plane in 
> affected planes and its layer_split property is enabled, order++ for 
> its split layer, so that when calculating the normalized_zpos of 
> master planes, the split layer of the slave plane is included, but the 
> max_slave_zorder does not include the split layer and keep zero 
> because there's only one slave plane in affacted planes, although we 
> actually use two slave layers in this commit.
> 
> In most cases, this bug does not result in a commit failure, but 
> assume the following situation:
>     slave_layer 0: zpos = 0, layer split enabled, normalized_zpos =
>     0;(use slave_layer 2 as its split layer)
>     master_layer 0: zpos = 2, layer_split enabled, normalized_zpos =
>     2;(use master_layer 2 as its split layer)
>     master_layer 1: zpos = 4, normalized_zpos = 4;
>     master_layer 3: zpos = 5, normalized_zpos = 5;
>     kcrtc_st->max_slave_zorder = 0;
> When we use master_layer 3 as a input of CU in function 
> komeda_compiz_set_input and check it with function 
> komeda_component_check_input, the parameter idx is equal to 
> normailzed_zpos minus max_slave_zorder, the value of idx is 5 and is 
> euqal to CU's max_active_inputs, so that komeda_component_check_input 
> returns a -EINVAL value.

Yes, indeed, you have found a bug in the calculations when layer_split is set.
But I was also looking through the code trying to find where layer_split gets set and I could not find it, do you have some extra patches?

> 
> To fix the bug described above, when calculating the max_slave_zorder 
> with the layer_split enabled, count the split layer in this 
> calculation directly.
> 
> Signed-off-by: hongchi.peng <hongchi.peng at siengine.com>
> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_kms.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c 
> b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> index fe46b0ebefea..b3db828284e4 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
> @@ -159,7 +159,7 @@ static int komeda_crtc_normalize_zpos(struct drm_crtc *crtc,
>  	struct drm_plane_state *plane_st;
>  	struct drm_plane *plane;
>  	struct list_head zorder_list;
> -	int order = 0, err;
> +	int order = 0, slave_zpos, err;

Also, the build bot has already flagged it, your patch needs some improvements.
slave_zpos needs to be u32 if it's going to be compared against max_slave_zorder.

Best regards,
Liviu

>  
>  	DRM_DEBUG_ATOMIC("[CRTC:%d:%s] calculating normalized zpos values\n",
>  			 crtc->base.id, crtc->name);
> @@ -199,10 +199,13 @@ static int komeda_crtc_normalize_zpos(struct drm_crtc *crtc,
>  				 plane_st->zpos, plane_st->normalized_zpos);
>  
>  		/* calculate max slave zorder */
> -		if (has_bit(drm_plane_index(plane), kcrtc->slave_planes))
> +		if (has_bit(drm_plane_index(plane), kcrtc->slave_planes)) {
> +			slave_zpos = plane_st->normalized_zpos;
> +			if (to_kplane_st(plane_st)->layer_split)
> +				slave_zpos++;
>  			kcrtc_st->max_slave_zorder =
> -				max(plane_st->normalized_zpos,
> -				    kcrtc_st->max_slave_zorder);
> +				max(slave_zpos, kcrtc_st->max_slave_zorder);
> +		}
>  	}
>  
>  	crtc_st->zpos_changed = true;
> --
> 2.34.1
> 

-- 
====================
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| but they're not |
| giving me the   |
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