Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
In-Reply-To: <CAE-0n51PiVo042oj8JrAxNTytmAoQx0kdqs_iCDffXa1+iur1A@mail.gmail.com>
References: <1656090912-18074-1-git-send-email-quic_khsieh@quicinc.com>
 <fa7f8bf1-33cd-5515-0143-6596df2bd740@quicinc.com> <CAE-0n51g-EVsC-i9=sJV-ySa8VnE+yT7cg=b-TNMi9+3uBiOVA@mail.gmail.com>
 <326912ff-9771-0711-366d-79acd436908b@quicinc.com> <CAE-0n51qrdrFtSr0vRwgYkMgSZfnzQuinaUROQsp30QoDchWQA@mail.gmail.com>
 <0ff3d6a3-dc5c-7c77-f8a1-6c4f6c1a3215@quicinc.com> <CAE-0n515hMKqQ+Vj1Sg54PpwkbWMYJ77QN+y+KZNBWymjhpWKw@mail.gmail.com>
 <66ff4642-f268-f5b0-7e28-b196368c508a@quicinc.com> <5cf094cf-343a-82d7-91c4-1284683f9748@quicinc.com>
 <CAE-0n51PiVo042oj8JrAxNTytmAoQx0kdqs_iCDffXa1+iur1A@mail.gmail.com>
From:   Stephen Boyd <swboyd@chromium.org>
User-Agent: alot/0.10
Date:   Fri, 24 Jun 2022 17:23:26 -0700
Message-ID: <CAE-0n50Qq2_eayXAUMzU29wKkpa6JZTG6J1dthUY1Y9tAjy_2Q@mail.gmail.com>
Subject: Re: [PATCH v1 2/3] drm/msm/dp: decoupling dp->id out of dp
 controller_id at scxxxx_dp_cfg table
To:     Abhinav Kumar <quic_abhinavk@quicinc.com>,
        Kuogee Hsieh <quic_khsieh@quicinc.com>, agross@kernel.org,
        airlied@linux.ie, bjorn.andersson@linaro.org, daniel@ffwll.ch,
        dianders@chromium.org, dmitry.baryshkov@linaro.org,
        dri-devel@lists.freedesktop.org, robdclark@gmail.com,
        sean@poorly.run, vkoul@kernel.org
Cc:     quic_aravindh@quicinc.com, quic_sbillaka@quicinc.com,
        freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Quoting Stephen Boyd (2022-06-24 17:11:01)
> Quoting Abhinav Kumar (2022-06-24 17:03:37)
> >
> > So let me try to explain this as this is what i understood from the
> > patch and how kuogee explained me.
> >
> > The ordering of the array still matters here and thats what he is trying
> > to address with the second change.
>
> The order of the array should not matter. That's the problem.

It seems like somewhere else the order of the array matters, presumably
while setting up encoders?

>
> >
> > So as per him, he tried to swap the order of entries like below and that
> > did not work and that is incorrect behavior because he still retained
> > the MSM_DP_CONTROLLER_x field for the table like below:
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
> > b/drivers/gpu/drm/msm/dp/dp_display.c
> > index dcd80c8a794c..7816e82452ca 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -140,8 +140,8 @@ static const struct msm_dp_config sc7180_dp_cfg = {
> >
> >   static const struct msm_dp_config sc7280_dp_cfg = {
> >          .descs = (const struct msm_dp_desc[]) {
> > -               [MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000,
> > .connector_type = DRM_MODE_CONNECTOR_DisplayPort, .wide_bus_en = true },
> >                  [MSM_DP_CONTROLLER_1] = { .io_start = 0x0aea0000,
> > .connector_type = DRM_MODE_CONNECTOR_eDP, .wide_bus_en = true },
> > +               [MSM_DP_CONTROLLER_0] = { .io_start = 0x0ae90000,
> > .connector_type = DRM_MODE_CONNECTOR_DisplayPort, .wide_bus_en = true },
> >          },
> >          .num_descs = 2,
> >   };
> >
> >
> > The reason order is important is because  in this function below, even
> > though it matches the address to find which one to use it loops through
> > the array and so the value of *id will change depending on which one is
> > located where.
> >
> > static const struct msm_dp_desc *dp_display_get_desc(struct
> > platform_device *pdev,
> >                               unsigned int *id)
>
> Thanks! We should fix this function to not overwrite the id.
>

Ah nevermind. I mixed up dp->id and h_tile_instance thinking one was
overwriting the other but that doesn't make any sense.