Re: [PATCH v4 2/3] drm/probe-helper: Check epoch counter in output_poll_execute()

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jan 20, 2021 at 6:10 PM Noralf Trønnes <noralf@tronnes.org> wrote:
>
> drm_helper_hpd_irq_event() checks the epoch counter to determine
> connector status change. This was introduced in
> commit 5186421cbfe2 ("drm: Introduce epoch counter to drm_connector").
> Do the same for output_poll_execute() so it can detect other changes
> beside connection status value changes.
>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/gpu/drm/drm_probe_helper.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index d6017726cc2a..e5432dcf6999 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -623,6 +623,7 @@ static void output_poll_execute(struct work_struct *work)
>         struct drm_connector_list_iter conn_iter;
>         enum drm_connector_status old_status;
>         bool repoll = false, changed;
> +       u64 old_epoch_counter;
>
>         if (!dev->mode_config.poll_enabled)
>                 return;
> @@ -659,8 +660,9 @@ static void output_poll_execute(struct work_struct *work)
>
>                 repoll = true;
>
> +               old_epoch_counter = connector->epoch_counter;
>                 connector->status = drm_helper_probe_detect(connector, NULL, false);
> -               if (old_status != connector->status) {
Was about to ask whether we're not missing connector status changes
here, but that's already handled. Not sure why this wasn't done as
part of the original patch, I'd include a cc: stable here.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> +               if (old_epoch_counter != connector->epoch_counter) {
>                         const char *old, *new;
>
>                         /*
> @@ -689,6 +691,9 @@ static void output_poll_execute(struct work_struct *work)
>                                       connector->base.id,
>                                       connector->name,
>                                       old, new);
> +                       DRM_DEBUG_KMS("[CONNECTOR:%d:%s] epoch counter %llu -> %llu\n",
> +                                     connector->base.id, connector->name,
> +                                     old_epoch_counter, connector->epoch_counter);
>
>                         changed = true;
>                 }
> --
> 2.23.0
>
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch