linux-kernel - [PATCH v5 06/13] drm/mediatek: Turn off the layers with zero width or height

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Date: Thu, 15 Feb 2024 18:11:12 +0800
From: Hsiao Chien Sung <shawn.sung@...iatek.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Chun-Kuang Hu <chunkuang.hu@...nel.org>
CC: Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>,
	Bibby Hsieh <bibby.hsieh@...iatek.com>, CK Hu <ck.hu@...iatek.com>, Sean Paul
	<seanpaul@...omium.org>, Fei Shao <fshao@...omium.org>, Jason Chen
	<jason-ch.chen@...iatek.corp-partner.google.com>, "Nancy . Lin"
	<nancy.lin@...iatek.com>, <dri-devel@...ts.freedesktop.org>,
	<linux-mediatek@...ts.infradead.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Hsiao Chien Sung <shawn.sung@...iatek.com>
Subject: [PATCH v5 06/13] drm/mediatek: Turn off the layers with zero width or height

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: 777b7bc86a0a3 ("drm/mediatek: Add ovl_adaptor support for MT8195")
Fixes: fa97fe71f6f93 ("drm/mediatek: Add ETHDR support for MT8195")

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 d4a13a1402148..68a20312ac6f1 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
@@ -157,7 +157,7 @@ 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 73dc4da3ba3bd..69872b77922eb 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;
 	}
-- 
2.18.0