Re: [PATCH v3 03/14] media: ov7670: hook s_power onto v4l2 core

From: Lubomir Rintel <lkundrak@v3.sk>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-media@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	James Cameron <quozl@laptop.org>, Pavel Machek <pavel@ucw.cz>,
	Libin Yang <lbyang@marvell.com>,
	Albert Wang <twang13@marvell.com>
Subject: Re: [PATCH v3 03/14] media: ov7670: hook s_power onto v4l2 core
Date: Wed, 28 Nov 2018 12:29:33 +0100	[thread overview]
Message-ID: <868bd721260bc8948835fe2a697a047ae2277cd0.camel@v3.sk> (raw)
In-Reply-To: <20181122122146.a6wydozsg676i3w7@valkosipuli.retiisi.org.uk>

On Thu, 2018-11-22 at 14:21 +0200, Sakari Ailus wrote:
> Hi Lubomir,
> 
> On Tue, Nov 20, 2018 at 11:03:08AM +0100, Lubomir Rintel wrote:
> > The commit 71862f63f351 ("media: ov7670: Add the ov7670_s_power function")
> > added a power control routing. However, it was not good enough to use as
> > a s_power() callback: it merely flipped on the power GPIOs without
> > restoring the register settings.
> > 
> > Fix this now and register an actual power callback.
> > 
> > Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> > 
> > ---
> > Changes since v2:
> > - Restore the controls, format and frame rate on power on
> > 
> >  drivers/media/i2c/ov7670.c | 50 +++++++++++++++++++++++++++++++++-----
> >  1 file changed, 44 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
> > index ead0c360df33..cbaab60aaaac 100644
> > --- a/drivers/media/i2c/ov7670.c
> > +++ b/drivers/media/i2c/ov7670.c
> > @@ -242,6 +242,7 @@ struct ov7670_info {
> >  	struct ov7670_format_struct *fmt;  /* Current format */
> >  	struct ov7670_win_size *wsize;
> >  	struct clk *clk;
> > +	int on;
> >  	struct gpio_desc *resetb_gpio;
> >  	struct gpio_desc *pwdn_gpio;
> >  	unsigned int mbus_config;	/* Media bus configuration flags */
> > @@ -1615,19 +1616,54 @@ static int ov7670_s_register(struct v4l2_subdev *sd, const struct v4l2_dbg_regis
> >  }
> >  #endif
> >  
> > -static int ov7670_s_power(struct v4l2_subdev *sd, int on)
> > +static void ov7670_power_on(struct v4l2_subdev *sd)
> >  {
> >  	struct ov7670_info *info = to_state(sd);
> >  
> > +	if (info->on)
> > +		return;
> > +
> >  	if (info->pwdn_gpio)
> > -		gpiod_set_value(info->pwdn_gpio, !on);
> > -	if (on && info->resetb_gpio) {
> > +		gpiod_set_value(info->pwdn_gpio, 0);
> > +	if (info->resetb_gpio) {
> >  		gpiod_set_value(info->resetb_gpio, 1);
> >  		usleep_range(500, 1000);
> >  		gpiod_set_value(info->resetb_gpio, 0);
> >  		usleep_range(3000, 5000);
> >  	}
> >  
> > +	info->on = true;
> > +}
> > +
> > +static void ov7670_power_off(struct v4l2_subdev *sd)
> > +{
> > +	struct ov7670_info *info = to_state(sd);
> > +
> > +	if (!info->on)
> > +		return;
> > +
> > +	if (info->pwdn_gpio)
> > +		gpiod_set_value(info->pwdn_gpio, 1);
> > +
> > +	info->on = false;
> > +}
> > +
> > +static int ov7670_s_power(struct v4l2_subdev *sd, int on)
> > +{
> > +	struct ov7670_info *info = to_state(sd);
> > +
> > +	if (info->on == on)
> > +		return 0;
> > +
> > +	if (on) {
> > +		ov7670_power_on (sd);
> > +		ov7670_apply_fmt(sd);
> > +		ov7675_apply_framerate(sd);
> > +		v4l2_ctrl_handler_setup(&info->hdl);
> > +	} else {
> > +		ov7670_power_off (sd);
> > +	}
> > +
> >  	return 0;
> >  }
> >  
> > @@ -1660,6 +1696,7 @@ static int ov7670_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
> >  static const struct v4l2_subdev_core_ops ov7670_core_ops = {
> >  	.reset = ov7670_reset,
> >  	.init = ov7670_init,
> > +	.s_power = ov7670_s_power,
> >  #ifdef CONFIG_VIDEO_ADV_DEBUG
> >  	.g_register = ov7670_g_register,
> >  	.s_register = ov7670_s_register,
> > @@ -1825,6 +1862,7 @@ static int ov7670_probe(struct i2c_client *client,
> >  		else
> >  			return ret;
> >  	}
> > +
> >  	if (info->clk) {
> >  		ret = clk_prepare_enable(info->clk);
> >  		if (ret)
> > @@ -1841,7 +1879,7 @@ static int ov7670_probe(struct i2c_client *client,
> >  	if (ret)
> >  		goto clk_disable;
> >  
> > -	ov7670_s_power(sd, 1);
> > +	ov7670_power_on(sd);
> >  
> >  	/* Make sure it's an ov7670 */
> >  	ret = ov7670_detect(sd);
> > @@ -1929,7 +1967,7 @@ static int ov7670_probe(struct i2c_client *client,
> >  hdl_free:
> >  	v4l2_ctrl_handler_free(&info->hdl);
> >  power_off:
> > -	ov7670_s_power(sd, 0);
> > +	ov7670_power_off(sd);
> >  clk_disable:
> >  	clk_disable_unprepare(info->clk);
> >  	return ret;
> > @@ -1945,7 +1983,7 @@ static int ov7670_remove(struct i2c_client *client)
> >  	v4l2_ctrl_handler_free(&info->hdl);
> >  	clk_disable_unprepare(info->clk);
> >  	media_entity_cleanup(&info->sd.entity);
> > -	ov7670_s_power(sd, 0);
> > +	ov7670_power_off(sd);
> >  	return 0;
> >  }
> >  
> 
> Could you consider instead switching to runtime PM? A few drivers such as
> the ov2685 driver does that already.

Yes, I'll take a look. Thanks for the suggestion. I didn't know such
thing exists, so it may take some time for me to grasp it though.

Take care,
Lubo

> 