linux-kernel - Re: [PATCH v1 2/3] drm/msm/dp: decoupling dp->id out of dp controller_id at scxxxx_dp

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Date:   Fri, 24 Jun 2022 16:30:59 -0700
From:   Kuogee Hsieh <quic_khsieh@...cinc.com>
To:     Stephen Boyd <swboyd@...omium.org>, <agross@...nel.org>,
        <airlied@...ux.ie>, <bjorn.andersson@...aro.org>,
        <daniel@...ll.ch>, <dianders@...omium.org>,
        <dmitry.baryshkov@...aro.org>, <dri-devel@...ts.freedesktop.org>,
        <robdclark@...il.com>, <sean@...rly.run>, <vkoul@...nel.org>
CC:     <quic_abhinavk@...cinc.com>, <quic_aravindh@...cinc.com>,
        <quic_sbillaka@...cinc.com>, <freedreno@...ts.freedesktop.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/3] drm/msm/dp: decoupling dp->id out of dp
 controller_id at scxxxx_dp_cfg table


On 6/24/2022 4:12 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2022-06-24 15:53:45)
>> MSM_DP_CONTROLLER_1 need to match to the index = 1 of sc7280_dp_cfg[] <== This is correct
>>
>> The problem is sc7280_dp_cfg[] have two entries since eDP place at index
>> of MSM_DP_CONTROLLER_1.
>>
>> but .num_desc = 1  <== this said only have one entry at sc7280_dp_cfg[]
>> table. Therefore eDP will never be found at for loop  at
>> _dpu_kms_initialize_displayport().
>>
> Yes, but what else does the MSM_DP_CONTROLLER_1 need to match? Because
> the intention of the previous commit was to make it so the order of
> sc7280_dp_cfg couldn't be messed up and not match the
> MSM_DP_CONTROLLER_1 value that lives in sc7280_intf[].


at  _dpu_kms_initialize_displayport()

> -		info.h_tile_instance[0] = i; <== assign i to become dp controller id, "i" is index of scxxxx_dp_cfg[]

This what I mean MSM_DP_CONTROLLER_1 need to match to index = 1 of 
scxxxx_dp_cfg[].

it it is not match, then MSM_DP_CONTROLLER_1 with match to different INTF.


>
>> Sorry, my mistake. it is not in drm_bridge_add.
>>
>> It should be in dpu_encoder_init() of _dpu_kms_initialize_displayport().
>>
>> can you make below changes (patch) to _dpu_kms_initialize_displayport().
>>
> Yes, I've made that change to try to understand the problem. I still
> don't understand, sadly. Does flipping the order of iteration through
> 'priv->dp' somehow mean that the crtc that is assigned to the eDP
> connector is left unchanged? Whereas without registering the eDP encoder
> first means we have to change the crtc for the eDP encoder and that
> can't be done atomically?