[PATCH 2/2] iommu/arm-smmu: Add system PM support

[Jonathan Cameron]

On Tue, 8 Aug 2017 13:14:18 +0100
Robin Murphy <robin.murphy at arm.com> wrote:

> On 08/08/17 12:18, Will Deacon wrote:
> > On Tue, Jul 18, 2017 at 01:44:42PM +0100, Robin Murphy wrote:  
> >> With all our hardware state tracked in such a way that we can naturally
> >> restore it as part of the necessary reset, resuming is trivial, and
> >> there's nothing to do on suspend at all.
> >>
> >> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> >> ---
> >>  drivers/iommu/arm-smmu.c | 12 ++++++++++++
> >>  1 file changed, 12 insertions(+)
> >>
> >> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> >> index 86897b7b81d8..0f5f06e9abfa 100644
> >> --- a/drivers/iommu/arm-smmu.c
> >> +++ b/drivers/iommu/arm-smmu.c
> >> @@ -2356,10 +2356,22 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
> >>  	return 0;
> >>  }
> >>  
> >> +static int __maybe_unused arm_smmu_pm_resume(struct device *dev)
> >> +{  
> > 
> > Did you actually get a warning here without the __maybe_unused annotation?
> > It looks like some other drivers just guard the thing with CONFIG_PM_SLEEP.  
> 
> I'm under the impression that the annotation is preferred over #ifdefs
> for new code (for the sake of coverage, I guess).
https://patchwork.kernel.org/patch/9734367/

Is a good thread discussing this.  Both coverage and to avoid common
pitfalls of the ifdef fun.

Jonathan
> 
> >> +	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
> >> +
> >> +	arm_smmu_device_reset(smmu);
> >> +	return 0;
> >> +}
> >> +
> >> +
> >> +static SIMPLE_DEV_PM_OPS(arm_smmu_pm_ops, NULL, arm_smmu_pm_resume);
> >> +
> >>  static struct platform_driver arm_smmu_driver = {
> >>  	.driver	= {
> >>  		.name		= "arm-smmu",
> >>  		.of_match_table	= of_match_ptr(arm_smmu_of_match),
> >> +		.pm = &arm_smmu_pm_ops,  
> > 
> > Cosmetic: can you tab-align this assignment please?  
> 
> Oops, I missed that - will do.
> 
> Robin.
> 
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