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SubjectRe: [PATCH v1] i2c: nvidia-gpu: drop empty stub for runtime pm
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On 11/7/20 11:04 AM, Vaibhav Gupta wrote:
> On Sat, Nov 07, 2020 at 01:51:51PM +0530, Vaibhav Gupta wrote:
>> After the commit c5eb1190074c ("PCI / PM: Allow runtime PM without callback
>> functions") we no more need empty stubs for runtime-pm to work.
>>
>> The driver has no device specific task(s) for .suspend() . The stub was
>> placed just for runtime-pm, which can be dropped now.
>>
>> Reported-by: Bjorn Helgaas <bhelgaas@google.com>
>> Signed-off-by: Vaibhav Gupta <vaibhavgupta40@gmail.com>
>> ---
>> drivers/i2c/busses/i2c-nvidia-gpu.c | 10 +---------
>> 1 file changed, 1 insertion(+), 9 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
>> index f9a69b109e5c..6b20601ffb13 100644
>> --- a/drivers/i2c/busses/i2c-nvidia-gpu.c
>> +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
>> @@ -353,15 +353,7 @@ static void gpu_i2c_remove(struct pci_dev *pdev)
>> pci_free_irq_vectors(pdev);
>> }
>>
>> -/*
>> - * We need gpu_i2c_suspend() even if it is stub, for runtime pm to work
>> - * correctly. Without it, lspci shows runtime pm status as "D0" for the card.
>> - * Documentation/power/pci.rst also insists for driver to provide this.
>> - */
>> -static __maybe_unused int gpu_i2c_suspend(struct device *dev)
>> -{
>> - return 0;
>> -}
>> +#define gpu_i2c_suspend NULL
>>
Perhaps we can put NULL directly into UNIVERSAL_DEV_PM_OPS() for the
suspend callback?

>> static __maybe_unused int gpu_i2c_resume(struct device *dev)
>> {
>> --
>> 2.28.0
>>
> The patch is only compile-tested.
>
It should work also system suspend point of view. This patch affects
also it since callbacks are set with the UNIVERSAL_DEV_PM_OPS(). Means
the same callback is used for runtime PM and system suspend.

I quickly debugged this with an another driver and PCI stack does put
the device into D3 state in system suspend from pci_prepare_to_sleep()
if the suspend callback is not set and device was on prior it.

Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>

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