On Fri, 15 Sept 2023 at 21:30, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
> dsi_wait4video_done() API wait 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.
>
> Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> ---
> 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 0c4ec0530efc..31495e423c56 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;
> +
> + data = dsi_read(msm_host, REG_DSI_STATUS0);
> +
> if (!(msm_host->mode_flags & MIPI_DSI_MODE_VIDEO))
> return;
We can probably skip reading REG_DSI_STATUS0 if the host is in CMD mode.
LGTM otherwise.
>
> + /* 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 */
> --
> 2.40.1
>
--
With best wishes
Dmitry
