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

From: John Stultz <john.stultz@linaro.org>
To: Kalyan Thota <kalyan_t@codeaurora.org>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	freedreno@lists.freedesktop.org,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	mkrishn@codeaurora.org, travitej@codeaurora.org,
	Doug Anderson <dianders@chromium.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Sean Paul <seanpaul@chromium.org>,
	hoegsberg@chromium.org, Rob Clark <robdclark@gmail.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Amit Pundir <amit.pundir@linaro.org>,
	Sumit Semwal <sumit.semwal@linaro.org>
Subject: Re: [PATCH 1/2] drm/msm/dpu: add support for color processing blocks in dpu driver
Date: Mon, 8 Jun 2020 15:36:47 -0700	[thread overview]
Message-ID: <CALAqxLWbhioSH4pFyM348VrGWxRXHQV1s9bdz6HArYguLtAFcw@mail.gmail.com> (raw)
In-Reply-To: <CALAqxLViRrga-XW2o1J1JutFdS1d-qmmgOrEP2beNygw3A7H4A@mail.gmail.com>

On Mon, Jun 8, 2020 at 3:25 PM John Stultz <john.stultz@linaro.org> wrote:
>
> On Wed, Mar 25, 2020 at 1:17 AM Kalyan Thota <kalyan_t@codeaurora.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@codeaurora.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.

thanks
-john