diff mbox series

[v2] drm/msm/dsi: skip the wait for video mode done if not applicable

Message ID 20230915204426.19011-1-quic_abhinavk@quicinc.com
State Superseded
Headers show
Series [v2] drm/msm/dsi: skip the wait for video mode done if not applicable | expand

Commit Message

Abhinav Kumar Sept. 15, 2023, 8:44 p.m. UTC
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>
---
 drivers/gpu/drm/msm/dsi/dsi_host.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

Comments

Dmitry Baryshkov Sept. 16, 2023, 12:30 a.m. UTC | #1
On Fri, 15 Sept 2023 at 23:45, Abhinav Kumar <quic_abhinavk@quicinc.com> wrote:
>
> 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>

> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
index 0c4ec0530efc..1a2afe31fa86 100644
--- a/drivers/gpu/drm/msm/dsi/dsi_host.c
+++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
@@ -1075,9 +1075,21 @@  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 */