On Tue, 24 Jan 2023 at 17:10, Vinod Polimera <vpolimer@xxxxxxxxxxxxxxxx> wrote: > > -----Original Message----- > > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > > Sent: Tuesday, January 24, 2023 5:52 AM > > To: Vinod Polimera (QUIC) <quic_vpolimer@xxxxxxxxxxx>; dri- > > devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; > > freedreno@xxxxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx > > Cc: Sankeerth Billakanti (QUIC) <quic_sbillaka@xxxxxxxxxxx>; linux- > > kernel@xxxxxxxxxxxxxxx; robdclark@xxxxxxxxx; dianders@xxxxxxxxxxxx; > > swboyd@xxxxxxxxxxxx; Kalyan Thota (QUIC) <quic_kalyant@xxxxxxxxxxx>; > > Kuogee Hsieh (QUIC) <quic_khsieh@xxxxxxxxxxx>; Vishnuvardhan > > Prodduturi (QUIC) <quic_vproddut@xxxxxxxxxxx>; Bjorn Andersson (QUIC) > > <quic_bjorande@xxxxxxxxxxx>; Abhinav Kumar (QUIC) > > <quic_abhinavk@xxxxxxxxxxx> > > Subject: Re: [PATCH Resend v11 05/15] drm/msm/dp: disable > > self_refresh_aware after entering psr > > > > WARNING: This email originated from outside of Qualcomm. Please be wary > > of any links or attachments, and do not enable macros. I hope such headers can be fixed on your side rather than being sent to the ML. > > > > On 19/01/2023 16:26, Vinod Polimera wrote: > > > From: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx> > > > > > > Updated frames get queued if self_refresh_aware is set when the > > > sink is in psr. To support bridge enable and avoid queuing of update > > > frames, reset the self_refresh_aware state after entering psr. > > > > I'm not convinced by this change. E.g. analogix code doesn't do this. > > Could you please clarify, why do you need to toggle the > > self_refresh_aware flag? > > > This was done to fix a bug reported by google. The use case is as follows: > CPU was running in a low frequency with debug build. > When self refresh was triggered by the library, due to system latency, the queued work was not scheduled. > There in another commit came and reinitialized the timer for the next PSR trigger. > This sequence happened multiple times and we found there were multiple works which are stuck and yet to be run. Where were workers stuck? Was it a busy loop around -EDEADLK / drm_modeset_backoff()? Also, what were ther ewma times for entry/exit avg times? I'm asking because the issue that you are describing sounds like a generic one, not the driver-specific issue. And being generic it should be handled in a generic fascion, in drm_self_refresh_helper.c. For example, I can imagine adding a variable to sr_data telling that the driver is in the process of transitioning to SR. Note: I did not perform a full research if it is a working solution or not. But from your description the driver really has to bail out early from drm_self_refresh_helper_entry_work(). > As PSR trigger is guarded by self_refresh_aware, we initialized the variable such that, if we are in PSR then until PSR exit, there cannot be any further PSR entry again. > https://chromium.googlesource.com/chromiumos/third_party/kernel/+/refs/tags/v5.15.90/drivers/gpu/drm/drm_self_refresh_helper.c#105 Yes, and that's what triggered my attention. We are using a set of helpers, that depend on the self_refresh_aware being true. And suddenly under the hood we disable this flag. I'd say that I can not predict the effect this will have on the helpers library behaviour. > This has solved few flicker issues during the stress testing. > > > > > > Signed-off-by: Sankeerth Billakanti <quic_sbillaka@xxxxxxxxxxx> > > > Signed-off-by: Vinod Polimera <quic_vpolimer@xxxxxxxxxxx> > > > --- > > > drivers/gpu/drm/msm/dp/dp_drm.c | 27 > > ++++++++++++++++++++++++++- > > > 1 file changed, 26 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c > > b/drivers/gpu/drm/msm/dp/dp_drm.c > > > index 029e08c..92d1a1b 100644 > > > --- a/drivers/gpu/drm/msm/dp/dp_drm.c > > > +++ b/drivers/gpu/drm/msm/dp/dp_drm.c > > > @@ -134,6 +134,8 @@ static void edp_bridge_atomic_enable(struct > > drm_bridge *drm_bridge, > > > struct drm_crtc_state *old_crtc_state; > > > struct msm_dp_bridge *dp_bridge = to_dp_bridge(drm_bridge); > > > struct msm_dp *dp = dp_bridge->dp_display; > > > + struct drm_connector *connector; > > > + struct drm_connector_state *conn_state = NULL; > > > > > > /* > > > * Check the old state of the crtc to determine if the panel > > > @@ -150,10 +152,22 @@ static void edp_bridge_atomic_enable(struct > > drm_bridge *drm_bridge, > > > > > > if (old_crtc_state && old_crtc_state->self_refresh_active) { > > > dp_display_set_psr(dp, false); > > > - return; > > > + goto psr_aware; > > > } > > > > > > dp_bridge_atomic_enable(drm_bridge, old_bridge_state); > > > + > > > +psr_aware: > > > + connector = > > drm_atomic_get_new_connector_for_encoder(atomic_state, > > > + drm_bridge->encoder); > > > + if (connector) > > > + conn_state = > > drm_atomic_get_new_connector_state(atomic_state, > > > + connector); > > > + > > > + if (conn_state) { > > > + conn_state->self_refresh_aware = dp->psr_supported; > > > + } > > > > No need to wrap a single line statement in brackets. > > > > > + > > > } > > > > > > static void edp_bridge_atomic_disable(struct drm_bridge *drm_bridge, > > > @@ -164,6 +178,14 @@ static void edp_bridge_atomic_disable(struct > > drm_bridge *drm_bridge, > > > struct drm_crtc_state *new_crtc_state = NULL, *old_crtc_state = NULL; > > > struct msm_dp_bridge *dp_bridge = to_dp_bridge(drm_bridge); > > > struct msm_dp *dp = dp_bridge->dp_display; > > > + struct drm_connector *connector; > > > + struct drm_connector_state *conn_state = NULL; > > > + > > > + connector = > > drm_atomic_get_old_connector_for_encoder(atomic_state, > > > + drm_bridge->encoder); > > > + if (connector) > > > + conn_state = > > drm_atomic_get_new_connector_state(atomic_state, > > > + connector); > > > > > > crtc = drm_atomic_get_old_crtc_for_encoder(atomic_state, > > > drm_bridge->encoder); > > > @@ -190,6 +212,9 @@ static void edp_bridge_atomic_disable(struct > > drm_bridge *drm_bridge, > > > * when display disable occurs while the sink is in psr state. > > > */ > > > if (new_crtc_state->self_refresh_active) { > > > + if (conn_state) > > > + conn_state->self_refresh_aware = false; > > > + > > > dp_display_set_psr(dp, true); > > > return; > > > } else if (old_crtc_state->self_refresh_active) { > > > > -- > > With best wishes > > Dmitry > > Thanks, > Vinod P. > -- With best wishes Dmitry
