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

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Message-ID: <cefa2bbb-5d29-1ea8-9c28-b5470a4c9535@nvidia.com>
Date:   Sat, 25 Apr 2020 16:47:42 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.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


On 4/25/20 4:44 PM, Dmitry Osipenko wrote:
> External email: Use caution opening links or attachments
>
>
> 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.

selecting test pattern thru v4l2 controls is once device graph is 
already set for TPG to choose test pattern modes.

But as internal TPG is b/w CSI and VI only, device graph is diff and for 
sensor device graph is different.


Based on internal discussion and discussion with Hans, decided to use 
kconfig for TPG Vs Sensor and TPG is rarely used only to test driver 
without sensor