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SubjectRe: [PATCH v3 1/2] i2c: davinci: Add PM Runtime Support
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On Tuesday 12 September 2017 01:41 AM, Grygorii Strashko wrote:
>
>
> 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@ti.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.

Can you please explain why this is the case? At least on DA850, I see
the runtime_idle callback invoked from rpm_idle() if
pm_runtime_put_sync() is used in the failure path.

Thanks
Sekhar

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