RE: [PATCH v13 00/13] Add PSR support for eDP

[Vinod Polimera <vpolimer@qti.qualcomm.com>]

> -----Original Message-----
> From: Doug Anderson <dianders@chromium.org>
> Sent: Thursday, March 2, 2023 2:02 AM
> To: 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; swboyd@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 v13 00/13] Add PSR support for eDP
> 
> Hi,
> 
> On Wed, Mar 1, 2023 at 11:06 AM Doug Anderson
> <dianders@chromium.org> wrote:
> >
> > Hi,
> >
> > On Sun, Feb 12, 2023 at 8:29 AM Vinod Polimera
> > <quic_vpolimer@quicinc.com> wrote:
> > >
> > > Changes in v2:
> > >   - Use dp bridge to set psr entry/exit instead of dpu_enocder.
> > >   - Don't modify whitespaces.
> > >   - Set self refresh aware from atomic_check.
> > >   - Set self refresh aware only if psr is supported.
> > >   - Provide a stub for msm_dp_display_set_psr.
> > >   - Move dp functions to bridge code.
> > >
> > > Changes in v3:
> > >   - Change callback names to reflect atomic interfaces.
> > >   - Move bridge callback change to separate patch as suggested by Dmitry.
> > >   - Remove psr function declaration from msm_drv.h.
> > >   - Set self_refresh_aware flag only if psr is supported.
> > >   - Modify the variable names to simpler form.
> > >   - Define bit fields for PSR settings.
> > >   - Add comments explaining the steps to enter/exit psr.
> > >   - Change DRM_INFO to drm_dbg_db.
> > >
> > > Changes in v4:
> > >   - Move the get crtc functions to drm_atomic.
> > >   - Add atomic functions for DP bridge too.
> > >   - Add ternary operator to choose eDP or DP ops.
> > >   - Return true/false instead of 1/0.
> > >   - mode_valid missing in the eDP bridge ops.
> > >   - Move the functions to get crtc into drm_atomic.c.
> > >   - Fix compilation issues.
> > >   - Remove dpu_assign_crtc and get crtc from drm_enc instead of
> dpu_enc.
> > >   - Check for crtc state enable while reserving resources.
> > >
> > > Changes in v5:
> > >   - Move the mode_valid changes into a different patch.
> > >   - Complete psr_op_comp only when isr is set.
> > >   - Move the DP atomic callback changes to a different patch.
> > >   - Get crtc from drm connector state crtc.
> > >   - Move to separate patch for check for crtc state enable while
> > > reserving resources.
> > >
> > > Changes in v6:
> > >   - Remove crtc from dpu_encoder_virt struct.
> > >   - fix crtc check during vblank toggle crtc.
> > >   - Misc changes.
> > >
> > > Changes in v7:
> > >   - Add fix for underrun issue on kasan build.
> > >
> > > Changes in v8:
> > >   - Drop the enc spinlock as it won't serve any purpose in
> > > protetcing conn state.(Dmitry/Doug)
> > >
> > > Changes in v9:
> > >   - Update commit message and fix alignment using spaces.(Marijn)
> > >   - Misc changes.(Marijn)
> > >
> > > Changes in v10:
> > >   - Get crtc cached in dpu_enc during obj init.(Dmitry)
> > >
> > > Changes in v11:
> > >   - Remove crtc cached in dpu_enc during obj init.
> > >   - Update dpu_enc crtc state on crtc enable/disable during self refresh.
> > >
> > > Changes in v12:
> > >   - Update sc7180 intf mask to get intf timing gen status
> > > based on DPU_INTF_STATUS_SUPPORTED bit.(Dmitry)
> > >   - Remove "clear active interface in the datapath cleanup" change
> > > as it is already included.
> > >
> > > Changes in v13:
> > >   - Move core changes to top of the series.(Dmitry)
> > >   - Drop self refresh aware disable change after psr entry.(Dmitry)
> > >
> > > Vinod Polimera (13):
> > >   drm: add helper functions to retrieve old and new crtc
> > >   drm/bridge: use atomic enable/disable callbacks for panel bridge
> > >   drm/bridge: add psr support for panel bridge callbacks
> > >   drm/msm/disp/dpu: check for crtc enable rather than crtc active to
> > >     release shared resources
> > >   drm/msm/disp/dpu: get timing engine status from intf status register
> > >   drm/msm/disp/dpu: wait for extra vsync till timing engine status is
> > >     disabled
> > >   drm/msm/disp/dpu: reset the datapath after timing engine disable
> > >   drm/msm/dp: use atomic callbacks for DP bridge ops
> > >   drm/msm/dp: Add basic PSR support for eDP
> > >   drm/msm/dp: use the eDP bridge ops to validate eDP modes
> > >   drm/msm/disp/dpu: use atomic enable/disable callbacks for encoder
> > >     functions
> > >   drm/msm/disp/dpu: add PSR support for eDP interface in dpu driver
> > >   drm/msm/disp/dpu: update dpu_enc crtc state on crtc enable/disable
> > >     during self refresh
> >
> > I'm curious what the plan is for landing this series. I could land the
> > first two in drm-misc if you want, but I'm a lowly committer and so I
> > couldn't make an immutable branch for you nor can I officially Ack the
> > changes to land in your branch. That means you'd be blocked for an
> > extra version. Do you already have a plan? If not, then maybe we need
> > to get in touch with one of the maintainers [1] of drm-misc? That's
> > documented [2] to be in their set of responsibilities.
> >
> > [1] https://drm.pages.freedesktop.org/maintainer-
> tools/repositories.html#drm-misc-repository
> > [2] https://drm.pages.freedesktop.org/maintainer-tools/maintainer-drm-
> misc.html#maintainer-s-duties
> 
> The above question about how we'd land this is still a good one, but
> perhaps less relevant quite yet because, at least in my testing, the
> current series doesn't work. :-/
> 
> I know previous versions worked, so I went back and tried older
> versions. It turns out that v12 _does_ work for me, but v13 doesn't
> work. The difference is very small. I'm assuming you made some changes
> in v13 and they looked so small that you just sent v13 out without
> testing? ...or, of course, there's always a possibility that I messed
> up in testing this myself, though I did repeat my results and they
> were consistent.
> 
> FWIW, my testing was roughly to do this on a device that had a
> PSR-enabled eDP display:
> 
> echo "dp_catalog_ctrl_set_psr" >
> /sys/kernel/debug/tracing/set_ftrace_filter
> echo function > /sys/kernel/debug/tracing/current_tracer
> echo 1 > /sys/kernel/debug/tracing/tracing_on
> cat /sys/kernel/debug/tracing/trace_pipe
> 
> I should see a splat in the trace buffers each time PSR is entered or
> exited. On v12 I get splats as the cursor on my screen blinks. On v13,
> it's just silence.
> 
> Please confirm that you tested v13. If you're confident that v13 works
> then I can dig further myself.

Thanks, Doug for catching this. 
I didn't per say test V13 as I did not make any changes apart from dropping a patch for flicker.
 Apparently flicker fix was reusing self-refresh aware variable and dropping the patch caused
not to initialize it. It was an honest mistake.

I pushed a new patch to set self-refresh aware as part of v14. 
It includes all the untouched patches of v13 plus one additional patch to set self-refresh aware.
I have tested these changes and PSR is getting exercised.

Thanks Again,
Vinod

> 
> -Doug