On Mon, Apr 1, 2013 at 12:47 PM, Rajagopal Venkat
<rajagopal.venkat@xxxxxxxxxx> wrote:
> On 1 April 2013 12:06, Prabhakar lad <prabhakar.csengg@xxxxxxxxx> wrote:
>> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
>>
>> Add pm_runtime support to the TI Davinci VPIF driver.
>>
>> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
>> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
>> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>> Cc: Sakari Ailus <sakari.ailus@xxxxxx>
>> Cc: Sekhar Nori <nsekhar@xxxxxx>
>> ---
>> Changes for v2:
>> 1: Removed use of clk API as pointed by Laurent and Sekhar.
>>
>> drivers/media/platform/davinci/vpif.c | 24 +++++++-----------------
>> 1 files changed, 7 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/media/platform/davinci/vpif.c b/drivers/media/platform/davinci/vpif.c
>> index 28638a8..599cabb 100644
>> --- a/drivers/media/platform/davinci/vpif.c
>> +++ b/drivers/media/platform/davinci/vpif.c
>> @@ -23,8 +23,8 @@
>> #include <linux/spinlock.h>
>> #include <linux/kernel.h>
>> #include <linux/io.h>
>> -#include <linux/clk.h>
>> #include <linux/err.h>
>> +#include <linux/pm_runtime.h>
>> #include <linux/v4l2-dv-timings.h>
>>
>> #include <mach/hardware.h>
>> @@ -44,7 +44,6 @@ static struct resource *res;
>> spinlock_t vpif_lock;
>>
>> void __iomem *vpif_base;
>> -struct clk *vpif_clk;
>>
>> /**
>> * ch_params: video standard configuration parameters for vpif
>> @@ -439,19 +438,15 @@ static int vpif_probe(struct platform_device *pdev)
>> goto fail;
>> }
>>
>> - vpif_clk = clk_get(&pdev->dev, "vpif");
>> - if (IS_ERR(vpif_clk)) {
>> - status = PTR_ERR(vpif_clk);
>> - goto clk_fail;
>> - }
>> - clk_prepare_enable(vpif_clk);
>> + pm_runtime_enable(&pdev->dev);
>> + pm_runtime_resume(&pdev->dev);
>> +
>> + pm_runtime_get(&pdev->dev);
>
> I don't see runtime-pm ops being registered. Can you explain how clock
> prepare/unprepare is taken care by runtime-pm?
>
The pm_runtime API handles the clock management for you.
For Davinci platform runtime PM support for clock management has
been added (You can find it in arch/arm/mach-davinci/pm_domain.c)
When runtime PM is enabled, the davinci runtime PM implementation will
use the pm_clk layer to enable/disable clocks on demand.
For more/detailed understanding you can go through the pm_runtime framework.
Regards,
--Prabhakar
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