linux-kernel - Re: [PATCH 1/2] drm/msm/dpu: add support for color processing blocks in dpu driver

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Message-ID: <CAF6AEGvGxyen5DbYCoc1x5ZeWiZo0mgvtsNev0k7WJnw+Xgqjg@mail.gmail.com>
Date:   Mon, 8 Jun 2020 15:54:19 -0700
From:   Rob Clark <robdclark@...il.com>
To:     John Stultz <john.stultz@...aro.org>
Cc:     Kalyan Thota <kalyan_t@...eaurora.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Krishna Manikandan <mkrishn@...eaurora.org>,
        Raviteja Tamatam <travitej@...eaurora.org>,
        Doug Anderson <dianders@...omium.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Sean Paul <seanpaul@...omium.org>,
        "Kristian H. Kristensen" <hoegsberg@...omium.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>,
        Sumit Semwal <sumit.semwal@...aro.org>
Subject: Re: [PATCH 1/2] drm/msm/dpu: add support for color processing blocks
 in dpu driver

On Mon, Jun 8, 2020 at 3:37 PM John Stultz <john.stultz@...aro.org> wrote:
>
> On Mon, Jun 8, 2020 at 3:25 PM John Stultz <john.stultz@...aro.org> wrote:
> >
> > On Wed, Mar 25, 2020 at 1:17 AM Kalyan Thota <kalyan_t@...eaurora.org> wrote:
> > >
> > > This change adds support to configure dspp blocks in
> > > the dpu driver.
> > >
> > > Macro description of the changes coming in this patch.
> > > 1) Add dspp definitions in the hw catalog.
> > > 2) Add capability to reserve dspp blocks in the display data path.
> > > 3) Attach the reserved block to the encoder.
> > >
> > > Signed-off-by: Kalyan Thota <kalyan_t@...eaurora.org>
> >
> > Hey all,
> >   With this patch now merged upstream, I'm seeing a regression on
> > db845c that I bisected down to it.
> >
> > When I boot up I see:
> > [   40.976737] [drm:_dpu_rm_check_lm_and_get_connected_blks] [dpu
> > error]failed to get dspp on lm 0
> > [   40.985600] [drm:_dpu_rm_check_lm_and_get_connected_blks] [dpu
> > error]failed to get dspp on lm 0
> > [   40.994587] [drm:_dpu_rm_check_lm_and_get_connected_blks] [dpu
> > error]failed to get dspp on lm 0
> > [   41.003492] [drm:_dpu_rm_check_lm_and_get_connected_blks] [dpu
> > error]failed to get dspp on lm 0
> > [   41.012283] [drm:_dpu_rm_make_reservation] [dpu error]unable to
> > find appropriate mixers
> > [   41.020369] [drm:dpu_rm_reserve] [dpu error]failed to reserve hw
> > resources: -119
> >
> > Over and over, and the display doesn't start up.
> >
> > I suspect we're supposed to catch the following check before the failure:
> >
> > +       if (!reqs->topology.num_dspp)
> > +               return true;
> >
> > I suspect the issue is in dpu_encoder_get_topology() we don't fully
> > initialize the topology structure on the stack before returning it.
> >
> > Does that sound plausible or is there likely some other cause?
>
> This guess is wrong. The topology.num_dspp is 2, but lm_cfg->dspp is
> coming back as zero.
>
> I'll continue digging to see if I can understand better whats going wrong.
>

It looks like no DSPP was added to 845, see sdm845_lm vs sc7180_lm


Kaylan, can this be fixed sanely to make DSPP optional, or should we
revert and try again next time?

BR,
-R