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    SubjectRe: [PATCH V2 08/20] dmaengine/amba-pl08x: support runtime PM
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    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:
    > >> Insert notifiers for the runtime PM API. With this the runtime PM layer kicks in
    > >> to action where used. This will also handle enabling/disabling of interface
    > >> clock (Code will be added in amba/bus.c by Russell King).
    > >
    > > I don't think this is correct...
    >
    > Sorry, but i couldn't get this comment completely. Mentioning clock
    > stuff here is incorrect or mentioning about your code? Or both?
    > Or something else?
    >
    > >> + pm_runtime_resume(&pl08x->adev->dev);
    > >
    > > Shouldn't this be pm_runtime_get_sync() ?
    >
    > >> + pm_runtime_suspend(&pl08x->adev->dev);
    > >
    > > And pm_runtime_put() ?
    >
    > >> + pm_runtime_suspend(&adev->dev);
    > >
    > > And pm_runtime_put() ?
    >
    > I have already fixed above in V3.
    >
    > > Lastly, we may want to make this even tighter to the actual period that
    > > the DMA is being used, rather than just the period that a driver has
    > > been allocated a channel. I'd rather have it done that way now (and
    > > tested) so that we achieve maximal effect from runtime PM, rather than
    > > having something which needs to be revisited again.
    > >
    > > IOW, if this is worth doing, then its worth doing properly first time.
    >
    > Correct. What about this one:
    >
    > ---
    > drivers/dma/amba-pl08x.c | 12 ++++++++++++
    > 1 files changed, 12 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
    > index 3fbaf0e..24353df 100644
    > --- a/drivers/dma/amba-pl08x.c
    > +++ b/drivers/dma/amba-pl08x.c
    > @@ -84,6 +84,7 @@
    > #include <linux/init.h>
    > #include <linux/interrupt.h>
    > #include <linux/module.h>
    > +#include <linux/pm_runtime.h>
    > #include <linux/seq_file.h>
    > #include <linux/slab.h>
    > #include <asm/hardware/pl080.h>
    > @@ -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;
    > }
    >
    > @@ -418,6 +420,8 @@ static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x,
    > /* Stop the channel and clear its interrupts */
    > pl08x_terminate_phy_chan(pl08x, ch);
    >
    > + pm_runtime_put(&pl08x->adev->dev);
    > +
    > /* Mark it as free */
    > ch->serving = NULL;
    > spin_unlock_irqrestore(&ch->lock, flags);
    > @@ -1855,6 +1859,9 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
    > goto out_no_pl08x;
    > }
    >
    > + pm_runtime_set_active(&adev->dev);
    > + pm_runtime_enable(&adev->dev);
    > +
    > /* Initialize memcpy engine */
    > dma_cap_set(DMA_MEMCPY, pl08x->memcpy.cap_mask);
    > pl08x->memcpy.dev = &adev->dev;
    > @@ -1993,6 +2000,8 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
    > dev_info(&pl08x->adev->dev, "DMA: PL%03x rev%u at 0x%08llx irq %d\n",
    > amba_part(adev), amba_rev(adev),
    > (unsigned long long)adev->res.start, adev->irq[0]);
    > +
    > + pm_runtime_put(&adev->dev);
    _put is probe looks suspect, why do you need this here as you are
    already setting the status as active, this _put will decrement your
    usage count and possibly call your runtime_suspend
    > return 0;
    >
    > out_no_slave_reg:
    > @@ -2011,6 +2020,9 @@ out_no_ioremap:
    > dma_pool_destroy(pl08x->pool);
    > out_no_lli_pool:
    > out_no_platdata:
    > + pm_runtime_put(&adev->dev);
    > + pm_runtime_disable(&adev->dev);
    > +
    > kfree(pl08x);
    > out_no_pl08x:
    > amba_release_regions(adev);
    >
    >


    --
    ~Vinod



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