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Subject: Re: [RFC PATCH v4 04/14] i2c: tegra: Fix runtime resume to re-init VI
 I2C
To:     Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>,
        <jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>,
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References: <1595548272-9809-1-git-send-email-skomatineni@nvidia.com>
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From:   Sowjanya Komatineni <skomatineni@nvidia.com>
Message-ID: <5d49d755-2eec-1c46-4d4c-87ec837bc5bd@nvidia.com>
Date:   Mon, 27 Jul 2020 13:58:37 -0700
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On 7/26/20 4:53 PM, Dmitry Osipenko wrote:
> 24.07.2020 02:51, Sowjanya Komatineni =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
>> VI I2C is on host1x bus and is part of VE power domain.
>>
>> During suspend/resume VE power domain goes through power off/on.
>>
>> So, controller reset followed by i2c re-initialization is required
>> after the domain power up.
>>
>> This patch fixes it.
>>
>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>> ---
>>   drivers/i2c/busses/i2c-tegra.c | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-teg=
ra.c
>> index 7b93c45..1bf3666 100644
>> --- a/drivers/i2c/busses/i2c-tegra.c
>> +++ b/drivers/i2c/busses/i2c-tegra.c
>> @@ -293,6 +293,8 @@ struct tegra_i2c_dev {
>>   	bool is_curr_atomic_xfer;
>>   };
>>  =20
>> +static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev, bool clk_reini=
t);
>> +
>>   static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
>>   		       unsigned long reg)
>>   {
>> @@ -675,8 +677,22 @@ static int __maybe_unused tegra_i2c_runtime_resume(=
struct device *dev)
>>   		goto disable_slow_clk;
>>   	}
>>  =20
>> +	/*
>> +	 * VI I2C device is attached to VE power domain which goes through
>> +	 * power ON/OFF during PM runtime resume/suspend. So, controller
>> +	 * should go through reset and need to re-initialize after power
>> +	 * domain ON.
>> +	 */
>> +	if (i2c_dev->is_vi) {
>> +		ret =3D tegra_i2c_init(i2c_dev, true);
>> +		if (ret)
>> +			goto disable_div_clk;
>> +	}
>> +
>>   	return 0;
>>  =20
>> +disable_div_clk:
>> +	clk_disable(i2c_dev->div_clk);
>>   disable_slow_clk:
>>   	clk_disable(i2c_dev->slow_clk);
>>   disable_fast_clk:
>>
> This look okay, but isn't RPM usage a bit too expensive for VI? Maybe
> RPM autodelay needs to be set for the I2C driver?
>
> Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
>
Thanks Dmitry. Will look into and have separate patch for VI I2C RPM=20
auto-delay out of this series sometime next week.

Regards

Sowjanya