drm/mediatek: Add pull-down MIPI operation in mtk_dsi_poweroff function

[ Upstream commit fa5d0a0205c34734c5b8daa77e39ac2817f63a10 ]

In the dsi_enable function, mtk_dsi_rxtx_control is to
pull up the MIPI signal operation. Before dsi_disable,
MIPI should also be pulled down by writing a register
instead of disabling dsi.

If disable dsi without pulling the mipi signal low, the value of
the register will still maintain the setting of the mipi signal being
pulled high.
After resume, even if the mipi signal is not pulled high, it will still
be in the high state.

Fixes: 2e54c14e310f ("drm/mediatek: Add DSI sub driver")
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/1653012007-11854-5-git-send-email-xinlei.lee@mediatek.com/
Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index c30af7ca5fadd27da1341123b8c6f2f93e76ad18..b0cb0ba53589f330bd87d2ff44264b0fb1ca29c6 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -682,6 +682,8 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
        mtk_dsi_reset_engine(dsi);
        mtk_dsi_lane0_ulp_mode_enter(dsi);
        mtk_dsi_clk_ulp_mode_enter(dsi);
+       /* set the lane number as 0 to pull down mipi */
+       writel(0, dsi->regs + DSI_TXRX_CTRL);
 
        mtk_dsi_disable(dsi);