linux-kernel - Re: [PATCH RFC 2/5] media: s5p-tv: Fix mixer driver to work with CCF

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Date:	Mon, 26 Aug 2013 18:03:59 +0200
From:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:	Mateusz Krawczuk <m.krawczuk@...tner.samsung.com>
Cc:	kgene.kim@...sung.com, kyungmin.park@...sung.com,
	t.figa@...sung.com, tomasz.figa@...il.com, rob.herring@...xeda.com,
	pawel.moll@....com, mark.rutland@....com, swarren@...dotorg.org,
	ian.campbell@...rix.com, rob@...dley.net, mturquette@...aro.org,
	thomas.abraham@...aro.org, t.stanislaws@...sung.com,
	m.chehab@...sung.com, s.nawrocki@...sung.com,
	m.szyprowski@...ung.com, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH RFC 2/5] media: s5p-tv: Fix mixer driver to work with CCF


Hi,

On Monday, August 26, 2013 01:38:31 PM Mateusz Krawczuk wrote:
> Replace clk_enable by clock_enable_prepare and clk_disable with clk_disable_unprepare.
> Clock prepare is required by Clock Common Framework, and old clock driver didn`t support it.
> Without it Common Clock Framework prints a warning.
> 
> Signed-off-by: Mateusz Krawczuk <m.krawczuk@...tner.samsung.com>
> ---
>  drivers/media/platform/s5p-tv/mixer_drv.c | 33 +++++++++++++++++++++++++------
>  1 file changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/platform/s5p-tv/mixer_drv.c b/drivers/media/platform/s5p-tv/mixer_drv.c
> index 51805a5..f889591 100644
> --- a/drivers/media/platform/s5p-tv/mixer_drv.c
> +++ b/drivers/media/platform/s5p-tv/mixer_drv.c
> @@ -345,21 +345,42 @@ fail:
>  
>  static int mxr_runtime_resume(struct device *dev)
>  {
> +	int ret = 0;

There is no need to initialize it to 0 here.

>  	struct mxr_device *mdev = to_mdev(dev);
>  	struct mxr_resources *res = &mdev->res;
>  
>  	mxr_dbg(mdev, "resume - start\n");
>  	mutex_lock(&mdev->mutex);
>  	/* turn clocks on */
> -	clk_enable(res->mixer);
> -	clk_enable(res->vp);
> -	clk_enable(res->sclk_mixer);
> +	ret = clk_prepare_enable(res->mixer);
> +	if (ret < 0) {
> +		dev_err(dev, "clk_prepare_enable(mixer) failed\n");

There is no consistency in the error messages between patch #1 and #2.

How's about changing error messages in the patch #2 to use

"%s: Failed to prepare and enable mixer clock!", __func__

form?

> +		goto fail;
> +	}
> +	ret = clk_prepare_enable(res->vp);
> +	if (ret < 0) {
> +		dev_err(dev, "clk_prepare_enable(vp) failed\n");
> +		goto fail_mixer;
> +	}
> +	ret = clk_prepare_enable(res->sclk_mixer);
> +	if (ret < 0) {
> +		dev_err(dev, "clk_prepare_enable(sclk_mixer) failed\n");
> +		goto fail_vp;
> +	}
>  	/* apply default configuration */
>  	mxr_reg_reset(mdev);
>  	mxr_dbg(mdev, "resume - finished\n");

While at it the above mxr_dbg() can be moved outside the mutex lock.

>  	mutex_unlock(&mdev->mutex);
>  	return 0;
> +fail_vp:
> +	clk_disable_unprepare(res->vp);
> +fail_mixer:
> +	clk_disable_unprepare(res->mixer);
> +fail:
> +	mutex_unlock(&mdev->mutex);
> +	dev_info(dev, "resume failed\n");

Shouldn't it be dev_err()?

Please also add mxr_dbg(mdev, "resume - finished\n") call here
to match the earlier mxr_dbg(mdev, "resume - start\n") one.

> +	return ret;
>  }
>  
>  static int mxr_runtime_suspend(struct device *dev)
> @@ -369,9 +390,9 @@ static int mxr_runtime_suspend(struct device *dev)
>  	mxr_dbg(mdev, "suspend - start\n");
>  	mutex_lock(&mdev->mutex);
>  	/* turn clocks off */
> -	clk_disable(res->sclk_mixer);
> -	clk_disable(res->vp);
> -	clk_disable(res->mixer);
> +	clk_disable_unprepare(res->sclk_mixer);
> +	clk_disable_unprepare(res->vp);
> +	clk_disable_unprepare(res->mixer);
>  	mutex_unlock(&mdev->mutex);
>  	mxr_dbg(mdev, "suspend - finished\n");
>  	return 0;

While at this driver please note that currently it defines its own macros to
use instead of dev_err(), dev_warn() and dev_info().

drivers/media/platform/s5p-tv/mixer.h:
...
#define mxr_err(mdev, fmt, ...)  dev_err(mdev->dev, fmt, ##__VA_ARGS__)
#define mxr_warn(mdev, fmt, ...) dev_warn(mdev->dev, fmt, ##__VA_ARGS__)
#define mxr_info(mdev, fmt, ...) dev_info(mdev->dev, fmt, ##__VA_ARGS__)
...

Since your patch adds dev_err() and dev_info() instances it would be a good
thing to remove mxr_*() macros in the preparatory patch.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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