Re: [PATCH] davinci: vpif: add pm_runtime support

Prabhakar Lad
2013-03-28T10:06:32Z

Hi Laurent,

Thanks for the quick review!

On Thu, Mar 28, 2013 at 2:39 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Prabhakar,
>
> Thanks for the patch.
>
> On Thursday 28 March 2013 14:20:32 Prabhakar lad wrote:
>> From: Lad, Prabhakar <prabhakar.csengg@gmail.com>
>>
>> Add pm_runtime support to the TI Davinci VPIF driver.
>> Along side this patch replaces clk_get() with devm_clk_get()
>> to simplify the error handling.
>>
>> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
>> ---
>> drivers/media/platform/davinci/vpif.c | 21 +++++++++++----------
>> 1 files changed, 11 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/media/platform/davinci/vpif.c
>> b/drivers/media/platform/davinci/vpif.c index 28638a8..7d14625 100644
>> --- a/drivers/media/platform/davinci/vpif.c
>> +++ b/drivers/media/platform/davinci/vpif.c
>> @@ -25,6 +25,7 @@
>> #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 +45,6 @@ static struct resource *res;
>> spinlock_t vpif_lock;
>>
>> void __iomem *vpif_base;
>> -struct clk *vpif_clk;
>>
>> /**
>> * ch_params: video standard configuration parameters for vpif
>> @@ -421,6 +421,7 @@ EXPORT_SYMBOL(vpif_channel_getfid);
>>
>> static int vpif_probe(struct platform_device *pdev)
>> {
>> + struct clk *vpif_clk;
>> int status = 0;
>>
>> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> @@ -439,12 +440,17 @@ static int vpif_probe(struct platform_device *pdev)
>> goto fail;
>> }
>>
>> - vpif_clk = clk_get(&pdev->dev, "vpif");
>> + vpif_clk = devm_clk_get(&pdev->dev, "vpif");
>> if (IS_ERR(vpif_clk)) {
>> status = PTR_ERR(vpif_clk);
>> goto clk_fail;
>> }
>> - clk_prepare_enable(vpif_clk);
>> + clk_put(vpif_clk);
>
> Why do you need to call clk_put() here ?
>
The above check is to see if the clock is provided, once done
we free it using clk_put().

>> + pm_runtime_enable(&pdev->dev);
>> + pm_runtime_resume(&pdev->dev);
>> +
>> + pm_runtime_get(&pdev->dev);
>
> Does runtime PM automatically handle your clock ? If so can't you remove clock
> handling from the driver completely ?
>
Yes pm runtime take care of enabling/disabling the clocks
so that we don't have to do it in drivers. I believe clock
handling is removed with this patch, with just devm_clk_get() remaining ;)

Regards,
--Prabhakar

>> spin_lock_init(&vpif_lock);
>> dev_info(&pdev->dev, "vpif probe success\n");
>> @@ -459,11 +465,6 @@ fail:
>>
>> static int vpif_remove(struct platform_device *pdev)
>> {
>> - if (vpif_clk) {
>> - clk_disable_unprepare(vpif_clk);
>> - clk_put(vpif_clk);
>> - }
>> -
>> iounmap(vpif_base);
>> release_mem_region(res->start, res_len);
>> return 0;
>> @@ -472,13 +473,13 @@ static int vpif_remove(struct platform_device *pdev)
>> #ifdef CONFIG_PM
>> static int vpif_suspend(struct device *dev)
>> {
>> - clk_disable_unprepare(vpif_clk);
>> + pm_runtime_put(dev);
>> return 0;
>> }
>>
>> static int vpif_resume(struct device *dev)
>> {
>> - clk_prepare_enable(vpif_clk);
>> + pm_runtime_get(dev);
>> return 0;
>> }
> --
> Regards,
>
> Laurent Pinchart
>