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

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Date:	Thu, 4 Aug 2011 10:49:56 +0530
From:	viresh kumar <viresh.kumar@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
	Pratyush ANAND <pratyush.anand@...com>,
	Rajeev KUMAR <rajeev-dlh.kumar@...com>,
	Bhupesh SHARMA <bhupesh.sharma@...com>,
	Shiraz HASHIM <shiraz.hashim@...com>,
	"vinod.koul@...el.com" <vinod.koul@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Vipin KUMAR <vipin.kumar@...com>,
	Armando VISCONTI <armando.visconti@...com>,
	Amit VIRDI <Amit.VIRDI@...com>,
	Vipul Kumar SAMAR <vipulkumar.samar@...com>,
	"viresh.linux@...il.com" <viresh.linux@...il.com>,
	Deepak SIKRI <deepak.sikri@...com>,
	"dan.j.williams@...el.com" <dan.j.williams@...el.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH V2 08/20] dmaengine/amba-pl08x: support runtime PM

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);
 	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);
 	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);


-- 
viresh
--
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