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

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Message-ID: <4352fda7-ecb6-4a5e-7d6c-a50537d8eaff@gmail.com>
Date:   Tue, 22 Feb 2022 13:46:29 +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 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.