linux-kernel - Re: [PATCH v2] drm/dp: move intel_dp_vsc_sdp

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Message-ID: <ec5ee910-469e-4224-28ca-336c9f589057@quicinc.com>
Date: Tue, 20 Feb 2024 11:27:18 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <dri-devel@...ts.freedesktop.org>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>,
        Tvrtko Ursulin
	<tvrtko.ursulin@...ux.intel.com>,
        <robdclark@...il.com>, <freedreno@...ts.freedesktop.org>,
        <intel-gfx@...ts.freedesktop.org>, <ville.syrjala@...ux.intel.com>,
        <quic_jesszhan@...cinc.com>, <linux-kernel@...r.kernel.org>,
        <intel-xe@...ts.freedesktop.org>
Subject: Re: [PATCH v2] drm/dp: move intel_dp_vsc_sdp_pack() to generic helper



On 2/20/2024 11:20 AM, Dmitry Baryshkov wrote:
> On Tue, 20 Feb 2024 at 21:05, Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
>>
>> On Tue, 20 Feb 2024 at 20:53, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>>>
>>>
>>>
>>> On 2/20/2024 10:49 AM, Dmitry Baryshkov wrote:
>>>> On Thu, 15 Feb 2024 at 21:08, Abhinav Kumar <quic_abhinavk@...cinc.com> wrote:
>>>>>
>>>>> intel_dp_vsc_sdp_pack() can be re-used by other DRM drivers as well.
>>>>> Lets move this to drm_dp_helper to achieve this.
>>>>>
>>>>> changes in v2:
>>>>>           - rebased on top of drm-tip
>>>>>
>>>>> Acked-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>>
>>>> v1 had an explicit comment before the ack:
>>>>
>>>
>>> Yes, I remember the comment. I did not make any changes to v2 other than
>>> just rebasing it on drm-tip to get the ack from i915 folks.
>>>
>>>>>      From my side, with the promise of the size fixup.
>>>>
>>>> However I observe neither a second patch removing the size argument
>>>> nor it being dropped as a part of this patch.
>>>>
>>>
>>> Yes, now that in v2 we got the ack for this patch, I can spin a v3 with
>>> the addition of the next patch to remove the size OR as another series
>>> so as to not block the main series which needs this patch.
>>>
>>> I would prefer the latter.
>>
>> It doesn't work this way. The comment should have been fixed for v2.
> 
> This probably deserves some explanation. Currently there is only one
> user of this function. So it is easy to fix it. Once there are several
> users, you have to fix all of them at the same time, patching
> different drm subtrees. That complicates the life of maintainers.
> 

Yes, understood. Its easier to fix it now if its really needed.

Actually, I think the reason the size was passed was to make sure
a valid struct dp_sdp *sdp was being passed.

If we drop the size, we need to have a if (!sdp) check as there is a 
memset followed by dereference.

So maybe, if we want to keep this API protected, its not too bad to have?