linux-kernel - Re: [RFC PATCH v10 6/9] media: tegra: Add Tegra210 Video input driver

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Message-ID: <3f2916eb-dcd4-58c3-4d45-7f88620d4a83@gmail.com>
Date:   Sun, 26 Apr 2020 02:44:58 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, frankc@...dia.com,
        hverkuil@...all.nl, sakari.ailus@....fi, helen.koike@...labora.com
Cc:     sboyd@...nel.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v10 6/9] media: tegra: Add Tegra210 Video input driver

26.04.2020 02:27, Sowjanya Komatineni пишет:
> 
> On 4/25/20 4:25 PM, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 26.04.2020 02:13, Dmitry Osipenko пишет:
>>> 24.04.2020 06:55, Sowjanya Komatineni пишет:
>>>> +static int __maybe_unused vi_runtime_resume(struct device *dev)
>>>> +{
>>>> +    struct tegra_vi *vi = dev_get_drvdata(dev);
>>>> +    int ret;
>>>> +
>>>> +    ret = regulator_enable(vi->vdd);
>>>> +    if (ret) {
>>>> +            dev_err(dev, "failed to enable VDD supply: %d\n", ret);
>>>> +            return ret;
>>>> +    }
>>>> +
>>>> +    ret = clk_set_rate(vi->clk, vi->soc->vi_max_clk_hz);
>>>> +    if (ret) {
>>>> +            dev_err(dev, "failed to set vi clock rate: %d\n", ret);
>>>> +            goto disable_vdd;
>>>> +    }
>>> Isn't setting clock rate using assigned-clocks in a device-tree enough?
>>> Could you please clarify why this vi_max_clk_hz is needed?
>>>
>> In that case it should be wrong to set the clock rate in the RPM
>> callback because RPM works asynchronously and RPM may not be suspended
>> on TGP -> sensor source switch.
> 
> Driver will not do TPG and Sensor switch dynamically.
> 
> Based on kconfig, it will only do TPG or Sensor and sensor will be
> default all the time once sensor support is added in next series.
> 

Doesn't V4L have a native support for the capture source selection? Why
it needs to be a compile-time option?

I think other drivers use a generic V4L "Image Processing Controls" with
a configurable test_pattern option.