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