linux-kernel - Re: [PATCH 1/3] drm/msm: don't clean up priv->kms prematurely

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Date: Mon, 22 Apr 2024 09:12:20 -0700
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn
 Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] drm/msm: don't clean up priv->kms prematurely



On 4/21/2024 3:35 PM, Dmitry Baryshkov wrote:
> On Sat, Apr 20, 2024 at 04:02:00PM -0700, Abhinav Kumar wrote:
>>
>>
>> On 4/19/2024 7:33 PM, Dmitry Baryshkov wrote:
>>> MSM display drivers provide kms structure allocated during probe().
>>> Don't clean up priv->kms field in case of an error. Otherwise probe
>>> functions might fail after KMS probe deferral.
>>>
>>
>> So just to understand this more, this will happen when master component
>> probe (dpu) succeeded but other sub-component probe (dsi) deferred?
>>
>> Because if master component probe itself deferred it will allocate priv->kms
>> again isnt it and we will not even hit here.
> 
> Master probing succeeds (so priv->kms is set), then kms_init fails at
> runtime, during binding of the master device. This results in probe
> deferral from the last component's component_add() function and reprobe
> attempt when possible (once the next device is added or probed). However
> as priv->kms is NULL, probe crashes.
> 

Got it, a better commit text would have helped here. Either way,

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>