linux-kernel - Re: [PATCH v3 8/9] drm/tegra: vic: Implement get_streamid

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Date:   Tue, 22 Feb 2022 14:02:08 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Mikko Perttunen <cyndis@...si.fi>,
        Mikko Perttunen <mperttunen@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, joro@...tes.org,
        will@...nel.org, robh+dt@...nel.org, robin.murphy@....com
Cc:     linux-tegra@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 8/9] drm/tegra: vic: Implement get_streamid_offset

22.02.2022 13:54, Mikko Perttunen пишет:
> On 2/22/22 12:46, Dmitry Osipenko wrote:
>> 22.02.2022 11:27, Mikko Perttunen пишет:
>>> On 2/21/22 22:10, Dmitry Osipenko wrote:
>>>> 21.02.2022 14:44, Mikko Perttunen пишет:
>>>>> On 2/19/22 20:54, Dmitry Osipenko wrote:
>>>>>> 19.02.2022 21:49, Dmitry Osipenko пишет:
>>>>>>> 18.02.2022 14:39, Mikko Perttunen пишет:
>>>>>>>> +static int vic_get_streamid_offset(struct tegra_drm_client
>>>>>>>> *client)
>>>>>>>> +{
>>>>>>>> +    struct vic *vic = to_vic(client);
>>>>>>>> +    int err;
>>>>>>>> +
>>>>>>>> +    err = vic_load_firmware(vic);
>>>>>>>
>>>>>>> You can't invoke vic_load_firmware() while RPM is suspended. Either
>>>>>>> replace this with RPM get/put or do something else.
>>>>>
>>>>> Why not, I'm not seeing any HW accesses in vic_load_firmware? Although
>>>>> it looks like it might race with the vic_load_firmware call in
>>>>> vic_runtime_resume which probably needs to be fixed.
>>>>
>>>> It was not clear from the function's name that h/w is untouched, I read
>>>> "load" as "upload" and then looked at vic_runtime_resume(). I'd rename
>>>> vic_load_firmware() to vic_prepare_firmware_image().
>>>>
>>>> And yes, technically lock is needed.
>>>
>>> Yep, I'll consider renaming it.
>>
>> Looking at this all again, I'd suggest to change:
>>
>> int get_streamid_offset(client)
>>
>> to:
>>
>> int get_streamid_offset(client, *offset)
>>
>> and bail out if get_streamid_offset() returns error. It's never okay to
>> ignore errors.
> 
> Sure, seems reasonable. We'll still need some error code to indicate
> that context isolation isn't available for the engine and continue on in
> that case but that's better than just ignoring all of them.

Yes, check for -EOPNOTSUPP and skip it.