4.19-stable review patch. If anyone has any objections, please let me know.
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From: Abhinav Kumar quic_abhinavk@quicinc.com
[ Upstream commit ab483e3adcc178254eb1ce0fbdfbea65f86f1006 ]
dsi_wait4video_done() API waits for the DSI video mode engine to become idle so that we can transmit the DCS commands in the beginning of BLLP. However, with the current sequence, the MDP timing engine is turned on after the panel's pre_enable() callback which can send out the DCS commands needed to power up the panel.
During those cases, this API will always timeout and print out the error spam leading to long bootup times and log flooding.
Fix this by checking if the DSI video engine was actually busy before waiting for it to become idle otherwise this is a redundant wait.
changes in v2: - move the reg read below the video mode check - minor fixes in commit text
Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/34 Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support") Signed-off-by: Abhinav Kumar quic_abhinavk@quicinc.com Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Patchwork: https://patchwork.freedesktop.org/patch/557853/ Link: https://lore.kernel.org/r/20230915204426.19011-1-quic_abhinavk@quicinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/msm/dsi/dsi_host.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 059578faa1c6d..5f4dd3659bf96 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1059,9 +1059,21 @@ static void dsi_wait4video_done(struct msm_dsi_host *msm_host)
static void dsi_wait4video_eng_busy(struct msm_dsi_host *msm_host) { + u32 data; + if (!(msm_host->mode_flags & MIPI_DSI_MODE_VIDEO)) return;
+ data = dsi_read(msm_host, REG_DSI_STATUS0); + + /* if video mode engine is not busy, its because + * either timing engine was not turned on or the + * DSI controller has finished transmitting the video + * data already, so no need to wait in those cases + */ + if (!(data & DSI_STATUS0_VIDEO_MODE_ENGINE_BUSY)) + return; + if (msm_host->power_on && msm_host->enabled) { dsi_wait4video_done(msm_host); /* delay 4 ms to skip BLLP */