linux-kernel - [PATCH 06/13] drm/mediatek: Turn off the layers with zero width or height

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Message-Id: <20240616-mediatek-drm-next-v1-6-7e8f9cf785d8@mediatek.com>
Date: Sun, 16 Jun 2024 16:29:16 +0800
From: Hsiao Chien Sung via B4 Relay <devnull+shawn.sung.mediatek.com@...nel.org>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>, 
 Daniel Vetter <daniel@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 CK Hu <ck.hu@...iatek.com>, Bibby Hsieh <bibby.hsieh@...iatek.com>, 
 Daniel Kurtz <djkurtz@...omium.org>, YT Shen <yt.shen@...iatek.com>, 
 Mao Huang <littlecvr@...omium.org>, "Nancy.Lin" <nancy.lin@...iatek.com>
Cc: dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 Hsiao Chien Sung <shawn.sung@...iatek.com>
Subject: [PATCH 06/13] drm/mediatek: Turn off the layers with zero width or
 height

From: Hsiao Chien Sung <shawn.sung@...iatek.com>

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@...iatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 2 +-
 drivers/gpu/drm/mediatek/mtk_ethdr.c            | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
index 02dd7dcdfedb..2b62d6475918 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -158,7 +158,7 @@ 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 d7d16482c947..b5484a286060 100644
--- a/drivers/gpu/drm/mediatek/mtk_ethdr.c
+++ b/drivers/gpu/drm/mediatek/mtk_ethdr.c
@@ -159,7 +159,12 @@ 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;
 	}

-- 
Git-146)