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Date:   Fri, 16 Dec 2022 13:38:45 +0100
From:   "Arnd Bergmann" <arnd@arndb.de>
To:     =?UTF-8?Q?Michel_D=C3=A4nzer?= <michel.daenzer@mailbox.org>,
        "Arnd Bergmann" <arnd@kernel.org>,
        "Harry Wentland" <harry.wentland@amd.com>,
        "Leo Li" <sunpeng.li@amd.com>,
        "Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>
Cc:     "Alan Liu" <HaoPing.Liu@amd.com>,
        "Pan, Xinhui" <Xinhui.Pan@amd.com>,
        "Wenjing Liu" <wenjing.liu@amd.com>, linux-kernel@vger.kernel.org,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        "Daniel Vetter" <daniel@ffwll.ch>,
        "George Shen" <george.shen@amd.com>,
        "Alex Deucher" <alexander.deucher@amd.com>,
        "Dave Airlie" <airlied@gmail.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Subject: Re: [PATCH] drm/amd/display: fix dp_retrieve_lttpr_cap return code
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On Thu, Dec 15, 2022, at 18:56, Michel D=C3=A4nzer wrote:
> On 12/15/22 17:37, Arnd Bergmann wrote:
/amd/display/dc/core/dc_link_dp.c
>> index af9411ee3c74..95dbfa4e996a 100644
>> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
>> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
>> @@ -5095,7 +5095,7 @@ enum dc_status dp_retrieve_lttpr_cap(struct dc_=
link *link)
>>  	bool vbios_lttpr_interop =3D link->dc->caps.vbios_lttpr_aware;
>> =20
>>  	if (!vbios_lttpr_interop || !link->dc->caps.extended_aux_timeout_su=
pport)
>> -		return false;
>> +		return DC_OK;
>
> 		return status;
>
> seems more appropriate. (Otherwise the status =3D DC_ERROR_UNEXPECTED=20
> initialization has no effect)

Ok, makes sense. I'd also remove the unused initialization in that
case though:

 enum dc_status dp_retrieve_lttpr_cap(struct dc_link *link)
 {
        uint8_t lttpr_dpcd_data[8];
-       enum dc_status status =3D DC_ERROR_UNEXPECTED;
-       bool is_lttpr_present =3D false;
+       enum dc_status status;
+       bool is_lttpr_present;
=20
        /* Logic to determine LTTPR support*/
        bool vbios_lttpr_interop =3D link->dc->caps.vbios_lttpr_aware;
=20
        if (!vbios_lttpr_interop || !link->dc->caps.extended_aux_timeout=
_support)
-               return false;
+               return DC_ERROR_UNEXPECTED;
=20
        /* By reading LTTPR capability, RX assumes that we will enable
         * LTTPR extended aux timeout if LTTPR is present.

I'll send that as a v2 once that passes my build test and nobody
has further suggestions.

       Arnd