linux-kernel - Re: [PATCH] davinci: vpif: add pm

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Date:	Thu, 28 Mar 2013 10:09:27 +0100
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Prabhakar lad <prabhakar.csengg@...il.com>
Cc:	DLOS <davinci-linux-open-source@...ux.davincidsp.com>,
	LMML <linux-media@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Hans Verkuil <hans.verkuil@...co.com>,
	Sakari Ailus <sakari.ailus@....fi>
Subject: Re: [PATCH] davinci: vpif: add pm_runtime support

Hi Prabhakar,

Thanks for the patch.

On Thursday 28 March 2013 14:20:32 Prabhakar lad wrote:
> From: Lad, Prabhakar <prabhakar.csengg@...il.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@...il.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 ?

> +	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 ?

>  	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

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