linux-kernel - Re: [PATCH] [media] ov9650: use msleep() for uncritical long delay

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Message-ID: <2045244.iMhNKFpdEc@avalon>
Date:   Thu, 19 Jan 2017 01:25:26 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Nicholas Mc Guire <hofrat@...dl.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Guennadi Liakhovetski <g.liakhovetski@....de>,
        Javier Martinez Canillas <javier@....samsung.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] ov9650: use msleep() for uncritical long delay

Hi Nicholas,

Thank you for the patch.

On Monday 16 Jan 2017 14:58:33 Nicholas Mc Guire wrote:
> ulseep_range() uses hrtimers and provides no advantage over msleep()
> for larger delays. Fix up the 25ms delays here to use msleep() and
> reduce the load on the hrtimer subsystem.
> 
> Link: http://lkml.org/lkml/2017/1/11/377
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

and applied to my tree. I'll send a pull request for v4.11.

> ---
> Problem found by coccinelle script
> 
> Patch was compile tested with: x86_64_defconfig + CONFIG_MEDIA_SUPPORT=m
> CONFIG_MEDIA_ANALOG_TV_SUPPORT=y, CONFIG_MEDIA_CONTROLLER=y
> CONFIG_VIDEO_V4L2_SUBDEV_API=y, CONFIG_MEDIA_SUBDRV_AUTOSELECT=n
> CONFIG_VIDEO_OV9650=m
> 
> Patch is aginast 4.10-rc3 (localversion-next is next-20170116)
> 
>  drivers/media/i2c/ov9650.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
> index 502c722..2de2fbb 100644
> --- a/drivers/media/i2c/ov9650.c
> +++ b/drivers/media/i2c/ov9650.c
> @@ -522,7 +522,7 @@ static void __ov965x_set_power(struct ov965x *ov965x,
> int on) if (on) {
>  		ov965x_gpio_set(ov965x->gpios[GPIO_PWDN], 0);
>  		ov965x_gpio_set(ov965x->gpios[GPIO_RST], 0);
> -		usleep_range(25000, 26000);
> +		msleep(25);
>  	} else {
>  		ov965x_gpio_set(ov965x->gpios[GPIO_RST], 1);
>  		ov965x_gpio_set(ov965x->gpios[GPIO_PWDN], 1);
> @@ -1438,7 +1438,7 @@ static int ov965x_detect_sensor(struct v4l2_subdev
> *sd)
> 
>  	mutex_lock(&ov965x->lock);
>  	__ov965x_set_power(ov965x, 1);
> -	usleep_range(25000, 26000);
> +	msleep(25);
> 
>  	/* Check sensor revision */
>  	ret = ov965x_read(client, REG_PID, &pid);

-- 
Regards,

Laurent Pinchart