From: Xinlei Lee xinlei.lee@mediatek.com
[ Upstream commit 91aeaed2c1147e3b1157dc084d23f190856a6c23 ]
According to Figure 16 Turnaround Procedure on page 36 in [1], you can see the status of LP-00 -> LP10 -> LP11. This state can correspond to the state of DSI from LP00 -> LP11 in mtk_dsi_lane_ready function in mtk_dsi.c.
LP-00 -> LP10 -> LP11 takes about 2*TLPX time (refer to [1] page 51 to see that TLPX is 50ns)
The delay at the end of the mtk_dsi_lane_ready function should be greater than the 2*TLPX specified by the DSI spec, and less than the time specified by the DSI_RX (generally 6ms to 40ms), to avoid problems caused by the RX specification
[1]:mipi_D-PHY_specification_v1-1
Fixes: 39e8d062b03c ("drm/mediatek: Keep dsi as LP00 before dcs cmds transfer") Signed-off-by: Xinlei Lee xinlei.lee@mediatek.com Acked-by: Sam Ravnborg sam@ravnborg.org Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Link: https://patchwork.kernel.org/project/linux-mediatek/patch/1673330093-6771-2-... Signed-off-by: Chun-Kuang Hu chunkuang.hu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/mediatek/mtk_dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c index 3b7d13028fb6b..9e1363c9fcdb4 100644 --- a/drivers/gpu/drm/mediatek/mtk_dsi.c +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c @@ -721,7 +721,7 @@ static void mtk_dsi_lane_ready(struct mtk_dsi *dsi) mtk_dsi_clk_ulp_mode_leave(dsi); mtk_dsi_lane0_ulp_mode_leave(dsi); mtk_dsi_clk_hs_mode(dsi, 0); - msleep(20); + usleep_range(1000, 3000); /* The reaction time after pulling up the mipi signal for dsi_rx */ } }