Patch "drm/mediatek: Turn off the layers with zero width or height" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/mediatek: Turn off the layers with zero width or height

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-mediatek-turn-off-the-layers-with-zero-width-or-.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a046ba82104cb6dc28280ec0ad97ac301fef14af
Author: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
Date:   Thu Jun 20 00:38:46 2024 +0800

    drm/mediatek: Turn off the layers with zero width or height
    
    [ Upstream commit 6b9946f4550d8dad8bc1af2db97286ca449af786 ]
    
    We found that IGT (Intel GPU Tool) will try to commit layers with
    zero width or height and lead to undefined behaviors in hardware.
    Disable the layers in such a situation.
    
    Fixes: 453c3364632a ("drm/mediatek: Add ovl_adaptor support for MT8195")
    Fixes: d886c0009bd0 ("drm/mediatek: Add ETHDR support for MT8195")
    Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
    Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
    Signed-off-by: Hsiao Chien Sung <shawn.sung@xxxxxxxxxxxx>
    Link: https://patchwork.kernel.org/project/dri-devel/patch/20240620-igt-v3-6-a9d62d2e2c7e@xxxxxxxxxxxx/
    Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
index 6bf6367853fba..8f0c47e868748 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -111,7 +111,7 @@ void mtk_ovl_adaptor_layer_config(struct device *dev, unsigned int idx,
 	merge = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_MERGE0 + idx];
 	ethdr = ovl_adaptor->ovl_adaptor_comp[OVL_ADAPTOR_ETHDR0];
 
-	if (!pending->enable) {
+	if (!pending->enable || !pending->width || !pending->height) {
 		mtk_merge_stop_cmdq(merge, cmdq_pkt);
 		mtk_mdp_rdma_stop(rdma_l, cmdq_pkt);
 		mtk_mdp_rdma_stop(rdma_r, cmdq_pkt);
diff --git a/drivers/gpu/drm/mediatek/mtk_ethdr.c b/drivers/gpu/drm/mediatek/mtk_ethdr.c
index 5a740d85bea65..0cf8c88994156 100644
--- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
+++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
@@ -160,7 +160,12 @@ void mtk_ethdr_layer_config(struct device *dev, unsigned int idx,
 	if (idx >= 4)
 		return;
 
-	if (!pending->enable) {
+	if (!pending->enable || !pending->width || !pending->height) {
+		/*
+		 * instead of disabling layer with MIX_SRC_CON directly
+		 * set the size to 0 to avoid screen shift due to mixer
+		 * mode switch (hardware behavior)
+		 */
 		mtk_ddp_write(cmdq_pkt, 0, &mixer->cmdq_base, mixer->regs, MIX_L_SRC_SIZE(idx));
 		return;
 	}