Re: [PATCH v14 14/14] drm/msm/dp: set self refresh aware based on PSR support

[Doug Anderson <dianders@chromium.org>]

Hi,

On Wed, Mar 29, 2023 at 8:16 AM Vinod Polimera
<vpolimer@qti.qualcomm.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Stephen Boyd <swboyd@chromium.org>
> > Sent: Monday, March 27, 2023 9:58 PM
> > To: Bjorn Andersson <andersson@kernel.org>; Vinod Polimera (QUIC)
> > <quic_vpolimer@quicinc.com>
> > Cc: dri-devel@lists.freedesktop.org; linux-arm-msm@vger.kernel.org;
> > freedreno@lists.freedesktop.org; devicetree@vger.kernel.org; linux-
> > kernel@vger.kernel.org; robdclark@gmail.com; dianders@chromium.org;
> > Kalyan Thota (QUIC) <quic_kalyant@quicinc.com>;
> > dmitry.baryshkov@linaro.org; Kuogee Hsieh (QUIC)
> > <quic_khsieh@quicinc.com>; Vishnuvardhan Prodduturi (QUIC)
> > <quic_vproddut@quicinc.com>; Bjorn Andersson (QUIC)
> > <quic_bjorande@quicinc.com>; Abhinav Kumar (QUIC)
> > <quic_abhinavk@quicinc.com>; Sankeerth Billakanti (QUIC)
> > <quic_sbillaka@quicinc.com>
> > Subject: Re: [PATCH v14 14/14] drm/msm/dp: set self refresh aware based
> > on PSR support
> >
> > Quoting Bjorn Andersson (2023-03-26 09:35:56)
> > > On Sun, Mar 26, 2023 at 09:27:23AM -0700, Bjorn Andersson wrote:
> > > > On Thu, Mar 02, 2023 at 10:03:17PM +0530, Vinod Polimera wrote:
> > > > > For the PSR to kick in, self_refresh_aware has to be set.
> > > > > Initialize it based on the PSR support for the eDP interface.
> > > > >
> > > >
> > > > When I boot my sc8280xp devices (CRD and X13s) to console with this
> > > > patch included I get a login prompt, and then there are no more screen
> > > > updates.
> > > >
> > > > Switching virtual terminal (ctrl+alt+fN) causes the screen to redraw.
> > > >
> > > > Blindly login in and launching Wayland works and from then on screen
> > > > updates works as expected.
> > > >
> > > > Switching from Wayland to another virtual terminal causes the problem
> > to
> > > > re-appear, no updates after the initial refresh, switching back go the
> > > > Wayland-terminal crashed the machine.
> > > >
> > >
> > > Also, trying to bring the eDP-screen back from DPMS gives me:
> > >
> > > <3>[ 2355.218099] [drm:dp_catalog_ctrl_set_pattern_state_bit [msm]]
> > *ERROR* set state_bit for link_train=1 failed
> > > <3>[ 2355.218926] [drm:dp_ctrl_setup_main_link [msm]] *ERROR* link
> > training #1 failed. ret=-110
> > > <3>[ 2355.262859] [drm:dp_catalog_ctrl_set_pattern_state_bit [msm]]
> > *ERROR* set state_bit for link_train=1 failed
> > > <3>[ 2355.263600] [drm:dp_ctrl_setup_main_link [msm]] *ERROR* link
> > training #1 failed. ret=-110
> > > <3>[ 2355.305211] [drm:dp_catalog_ctrl_set_pattern_state_bit [msm]]
> > *ERROR* set state_bit for link_train=1 failed
> > > <3>[ 2355.305955] [drm:dp_ctrl_setup_main_link [msm]] *ERROR* link
> > training #1 failed. ret=-110
> > > <3>[ 2355.345250] [drm:dp_catalog_ctrl_set_pattern_state_bit [msm]]
> > *ERROR* set state_bit for link_train=1 failed
> > > <3>[ 2355.346026] [drm:dp_ctrl_setup_main_link [msm]] *ERROR* link
> > training #1 failed. ret=-110
> > > <3>[ 2355.405650] [drm:dp_display_process_hpd_high [msm]] *ERROR*
> > failed to complete DP link training
> > > <3>[ 2355.668988]
> > [drm:dpu_encoder_phys_vid_wait_for_commit_done:488] [dpu
> > error]vblank timeout
> > > <3>[ 2355.669030] [drm:dpu_kms_wait_for_commit_done:510] [dpu
> > error]wait for commit done returned -110
> > > <3>[ 2355.699989] [drm:dpu_encoder_frame_done_timeout:2398] [dpu
> > error]enc35 frame done timeout
> > >
> > > And then the machine just resets.
> > >
> >
> > I saw similar behavior on ChromeOS after we picked the PSR patches into
> > our kernel. I suspect it's the same problem. I switched back and forth
> > between VT2 and the OOBE screen with ctrl+alt+forward and that showed
> > what I typed on the virtual terminal after switching back and forth.
> > It's like the redraw only happens once on the switch and never again. I
> > switched back and forth enough times that it eventually crashed the
> > kernel and rebooted. This was on CRD (sc7280-herobrine-crd.dts).
> >
> > There's an animation on the OOBE screen that is working though, so
> > perhaps PSR is working with the chrome compositor but not the virtual
> > terminal? I haven't investigated.
>
> I was able to reproduce the issue where in virtual terminal, I don't see any screen refresh despite typing in.
> In the VT mode, I see that PSR is entered, but despite typing in there are no atomic commits triggered, hence the last buffer was always refreshed.
>
> Queries from my side to Rob & Doug:
> 1) In VT mode, does the framework operates in single buffer mode without any commit for new updates ?
> 2) if above is true then, how does driver know if the framework operates in single buffer mode, to make any appropriate action
> 3) what is the expected behavior with the driver here ? should it return atomic_check failure, for single buffer mode operation or, it should exit PSR ?
> 4) is there any HINT passed down to the driver so that we can bank on it and act accordingly?

I haven't looked at this detail about PSR before, and I left my
PSR-enabled device at home so I can't easily test this right now. That
being said, from a bit of searching I would guess that
msm_framebuffer_dirtyfb() is somehow involved here. Are things better
if you get rid of the test against 'msm_fb->dirtyfb'?

I at least used ftrace to confirm that on a different device
msm_framebuffer_dirtyfb() is not called during normal ChromeOS usage
but it _is_ called in VT2 usage.

-Doug