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Subject: Re: [RFC PATCH v6 6/9] media: tegra: Add Tegra210 Video input driver
To:     Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
        <jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
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From:   Sowjanya Komatineni <skomatineni@nvidia.com>
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On 4/6/20 9:11 AM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
>
>
> 06.04.2020 18:41, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>> On 4/5/20 2:11 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 04.04.2020 04:25, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>>> ...
>>>> +static int tegra_vi_tpg_channels_alloc(struct tegra_vi *vi)
>>>> +{
>>>> +     struct tegra_vi_channel *chan, *tmp;
>>>> +     unsigned int port_num;
>>>> +     unsigned int nchannels =3D vi->soc->vi_max_channels;
>>>> +     int ret =3D 0;
>>>> +
>>>> +     for (port_num =3D 0; port_num < nchannels; port_num++) {
>>>> +             /*
>>>> +              * Do not use devm_kzalloc as memory is freed immediatel=
y
>>>> +              * when device instance is unbound but application
>>>> might still
>>>> +              * be holding the device node open. Channel memory
>>>> allocated
>>>> +              * with kzalloc is freed during video device release
>>>> callback.
>>>> +              */
>>>> +             chan =3D kzalloc(sizeof(*chan), GFP_KERNEL);
>>> Why anyone would want to unbind this driver in practice?
>>>
>>> I think it should make more sense to set suppress_bind_attrs=3Dtrue.
>>  From the previous feedback of patch series, we need to support
>> unbind/bind and looks like this driver should also support to built as a
>> module.
> If module unloading is also affected, then perhaps you should use
> get/put_device() to not allow freeing the resources until they're still
> in-use.
>
> I suppose that it should be up to the V4L core to keep the device alive
> while needed, rather than to put the burden to the individual drivers.

Hans/Thierry, Can you please comment on this?