Re: [PATCH V2 08/20] dmaengine/amba-pl08x: support runtime PM

[viresh kumar]

On 08/04/2011 11:06 AM, Koul, Vinod wrote:
> On Thu, 2011-08-04 at 10:49 +0530, viresh kumar wrote:
>> On 08/03/2011 06:09 PM, Russell King - ARM Linux wrote:
>>> On Mon, Aug 01, 2011 at 03:07:18PM +0530, Viresh Kumar wrote:
>> @@ -405,6 +406,7 @@ pl08x_get_phy_channel(struct pl08x_driver_data *pl08x,
>>  		return NULL;
>>  	}
>>  
>> +	pm_runtime_get_sync(&pl08x->adev->dev);
> this should be ideally one of the first things you would do not last.
> get_sync will ensure your .runtime_resume callback is called before it
> returns (if its suspended)
>>  	return ch;
>>  }

Until this point we are not touching the registers at all. And they will
accessed after this point only.

>> +	pm_runtime_put(&adev->dev);
> _put is probe looks suspect, why do you need this here 

To save power.

> as you are already setting the status as active, this _put will decrement your
> usage count and possibly call your runtime_suspend

We set status as active, as amba/bus layer has enabled it before calling
probe and it doesn't put it.

As DMA will not be used until get_phy_channel() is called, so we can save
some energy here too. So i put it here.

-- 
viresh
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