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From:   Stephen Boyd <swboyd@chromium.org>
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Date:   Fri, 24 Jun 2022 13:00:37 -0700
Message-ID: <CAE-0n52RW+UFJ=hqMWjwR8qvEbww7QjzPW1nhL3Atd97QXAnYw@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:     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_abhinavk@quicinc.com, quic_aravindh@quicinc.com,
        quic_sbillaka@quicinc.com, freedreno@lists.freedesktop.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
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Quoting Kuogee Hsieh (2022-06-24 10:15:11)
> Current the index (dp->id) of DP descriptor table (scxxxx_dp_cfg[]) are tightly
> coupled with DP controller_id. This means DP use controller id 0 must be placed
> at first entry of DP descriptor table (scxxxx_dp_cfg[]). Otherwise the internal
> INTF will mismatch controller_id. This will cause controller kickoff wrong
> interface timing engine and cause dpu_encoder_phys_vid_wait_for_commit_done
> vblank timeout error.
>
> This patch add controller_id field into struct msm_dp_desc to break the tightly
> coupled relationship between index (dp->id) of DP descriptor table with DP
> controller_id.

Please no. This reverts the intention of commit bb3de286d992
("drm/msm/dp: Support up to 3 DP controllers")

    A new enum is introduced to document the connection between the
    instances referenced in the dpu_intf_cfg array and the controllers in
    the DP driver and sc7180 is updated.

It sounds like the intent of that commit failed to make a strong enough
connection. Now it needs to match the INTF number as well? I can't
really figure out what is actually wrong, because this patch undoes that
intentional tight coupling. Is the next patch the important part that
flips the order of the two interfaces?