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SubjectRe: [PATCH] drm/msm/dp: Sleep properly in dp_hpd_handler kthread
On 2020-09-17 15:44, Stephen Boyd wrote:
> We shouldn't be waiting for an event here with a timeout of 100ms when
> we're not in the 'timeout' arm of the if condition. Instead we should
> be
> sleeping in the interruptible state (S) until something happens and we
> need to wakeup. Right now this kthread is running almost all the time
> because it sleeps for 100ms, wakes up, sees there's nothing to do, and
> then starts the process all over again. Looking at top it shows up in
> the D state (uninterruptible) because it uses wait_event_timeout(). FIx
> this up.
>
> Cc: Tanmay Shah <tanmay@codeaurora.org>
> Cc: Kuogee Hsieh <khsieh@codeaurora.org>
> Reported-by: Douglas Anderson <dianders@chromium.org>
> Fixes: 8ede2ecc3e5e ("drm/msm/dp: Add DP compliance tests on
> Snapdragon Chipsets")
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Kuogee Hsieh <khsieh@codeaurora.org>
> ---
>
> Based on msm-next-dp of https://gitlab.freedesktop.org/drm/msm.git
>
> drivers/gpu/drm/msm/dp/dp_display.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> b/drivers/gpu/drm/msm/dp/dp_display.c
> index 05a97e097edf..e175aa3fd3a9 100644
> --- a/drivers/gpu/drm/msm/dp/dp_display.c
> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> @@ -970,9 +970,8 @@ static int hpd_event_thread(void *data)
> (dp_priv->event_pndx == dp_priv->event_gndx),
> EVENT_TIMEOUT);
> } else {
> - wait_event_timeout(dp_priv->event_q,
> - (dp_priv->event_pndx != dp_priv->event_gndx),
> - EVENT_TIMEOUT);
> + wait_event_interruptible(dp_priv->event_q,
> + (dp_priv->event_pndx != dp_priv->event_gndx));
> }
> spin_lock_irqsave(&dp_priv->event_lock, flag);
> todo = &dp_priv->event_list[dp_priv->event_gndx];
>
> base-commit: 937f941ca06f2f3ab64baebf31be2c16d57ae7b8

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