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

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Message-ID: <2983577f-fec9-f24c-0563-6d1f0e1dd5d8@gmail.com>
Date:   Sun, 26 Apr 2020 02:25:58 +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 02:13, 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.