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

[Peng Hongchi/彭洪驰]

Hi, all:

 I'm sorry that I forgot to add a pair of brackets, and I'll send it again soon.

Best Regards,
Hongchi Peng

-----邮件原件-----
发件人: hongchi.peng <hongchi.peng at siengine.com> 
发送时间: 2024年8月21日 16:19
收件人: liviu.dudau at arm.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; Peng Hongchi/彭洪驰 <hongchi.peng at siengine.com>
主题: [PATCH] drm: komeda: Fix an issue related to normalized zpos

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.

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 | 8 +++++---
 1 file changed, 5 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..0554954c8cea 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;
 
 	DRM_DEBUG_ATOMIC("[CRTC:%d:%s] calculating normalized zpos values\n",
 			 crtc->base.id, crtc->name);
@@ -200,9 +200,11 @@ static int komeda_crtc_normalize_zpos(struct drm_crtc *crtc,
 
 		/* calculate max slave zorder */
 		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