linux-kernel - Re: [PATCH v3 1/2] i2c: davinci: Add PM Runtime Support

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Message-ID: <94b7a185-4cde-03e6-cc17-f64d5d28c9f2@ti.com>
Date:   Mon, 11 Sep 2017 15:11:42 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Franklin S Cooper Jr <fcooper@...com>,
        Sekhar Nori <nsekhar@...com>, <wsa@...-dreams.de>,
        <robh+dt@...nel.org>, <linux@...linux.org.uk>,
        <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <vigneshr@...com>
Subject: Re: [PATCH v3 1/2] i2c: davinci: Add PM Runtime Support



On 09/11/2017 03:07 PM, Franklin S Cooper Jr wrote:
> 
> 
> On 09/11/2017 06:29 AM, Sekhar Nori wrote:
>> On Friday 08 September 2017 11:24 PM, Franklin S Cooper Jr wrote:
>>> 66AK2G has I2C instances that are not apart of the ALWAYS_ON power domain
>>> like other Keystone 2 SoCs and OMAPL138. Therefore, pm_runtime
>>
>> unlike ?
>>
>>> is required to insure the power domain used by the specific I2C instance is
>>> properly turned on along with its functional clock.
>>>
>>> Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
>>> ---
>>> Version 3 changes:
>>> Remove several statements that set clk to NULL
>>> Fix error path
>>>
>>>   drivers/i2c/busses/i2c-davinci.c | 64 +++++++++++++++++++++++++++++++++-------
>>>   1 file changed, 53 insertions(+), 11 deletions(-)
>>
>>> @@ -802,12 +821,22 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>>>   	dev->clk = devm_clk_get(&pdev->dev, NULL);
>>>   	if (IS_ERR(dev->clk))
>>>   		return PTR_ERR(dev->clk);
>>> -	clk_prepare_enable(dev->clk);
>>>   
>>>   	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>   	dev->base = devm_ioremap_resource(&pdev->dev, mem);
>>>   	if (IS_ERR(dev->base)) {
>>> -		r = PTR_ERR(dev->base);
>>> +		return PTR_ERR(dev->base);
>>> +	}
>>> +
>>> +	pm_runtime_set_autosuspend_delay(dev->dev,
>>> +					 DAVINCI_I2C_PM_TIMEOUT);
>>> +	pm_runtime_use_autosuspend(dev->dev);
>>> +
>>> +	pm_runtime_enable(dev->dev);
>>> +
>>> +	r = pm_runtime_get_sync(dev->dev);
>>> +	if (r < 0) {
>>> +		dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
>>>   		goto err_unuse_clocks;
>>
>> You end up doing a pm_runtime_put_sync() on failure here, instead of
>> pm_runtime_put_noidle() like rest of the patch.
>>
>> May be handle this failure here instead of relying on the goto path.
> 
> Ok

I think, it's not necessary - pm_runtime_put_sync() can be used in this case
 (and used the same way in many other drivers).
In case, of failure in this place - pm_runtime_put_sync() will just decrement usage counter.


>>
>>>   	}
>>>   
>>> @@ -849,27 +878,40 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>>>   	if (r)
>>>   		goto err_unuse_clocks;
>>>   
>>> +	pm_runtime_mark_last_busy(dev->dev);
>>> +	pm_runtime_put_autosuspend(dev->dev);
>>> +
>>>   	return 0;
>>>   
>>>   err_unuse_clocks:
>>> -	clk_disable_unprepare(dev->clk);
>>> -	dev->clk = NULL;
>>> +	pm_runtime_dont_use_autosuspend(dev->dev);
>>> +	pm_runtime_put_sync(dev->dev);
>>> +	pm_runtime_disable(dev->dev);
>>> +
>>>   	return r;
>>>   }
>>
>> Thanks,
>> Sekhar
>>

-- 
regards,
-grygorii