linux-kernel - Re: [PATCH v2 2/3] media: mt9m111: fix device power usage

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Message-ID: <20220920103412.cxpykimes3d7rz7i@lati>
Date:   Tue, 20 Sep 2022 12:34:12 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     mchehab@...nel.org, sakari.ailus@...ux.intel.com,
        laurent.pinchart+renesas@...asonboard.com, akinobu.mita@...il.com,
        jacopo+renesas@...ndi.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] media: mt9m111: fix device power usage

Hi Marco

On Tue, Sep 20, 2022 at 12:27:04PM +0200, Jacopo Mondi wrote:
> Hi Marco
>
> On Fri, Sep 16, 2022 at 03:57:12PM +0200, Marco Felsch wrote:
> > Currently the driver turn off the power after probe and toggle it during
> > .stream by using the .s_power callback. This is problematic since other
> > callbacks like .set_fmt accessing the hardware as well which will fail.
> > So in the end the default format is the only supported format.
> >
> > Remove the hardware register access from the callbacks and instead sync
> > the state once right before the stream gets enabled to fix this for
> > .set_fmt() and .set_selection(). For the debug register access we need
> > to turn the device on/off before accessing the registers to fix this and
> > finally for the ctrls access we need the device to be powered to fix
> > this.
> >
> > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> > ---
> > Changelog:
> >
> > v2:
> > - squash patch 2 and 3
> > ---
> >  drivers/media/i2c/mt9m111.c | 40 ++++++++++++++++++++-----------------
> >  1 file changed, 22 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
> > index 52be1c310455..8de93ab99cbc 100644
> > --- a/drivers/media/i2c/mt9m111.c
> > +++ b/drivers/media/i2c/mt9m111.c
> > @@ -455,7 +455,7 @@ static int mt9m111_set_selection(struct v4l2_subdev *sd,
> >  	struct mt9m111 *mt9m111 = to_mt9m111(client);
> >  	struct v4l2_rect rect = sel->r;
> >  	int width, height;
> > -	int ret, align = 0;
> > +	int align = 0;
> >
> >  	if (sel->which != V4L2_SUBDEV_FORMAT_ACTIVE ||
> >  	    sel->target != V4L2_SEL_TGT_CROP)
> > @@ -481,14 +481,11 @@ static int mt9m111_set_selection(struct v4l2_subdev *sd,
> >  	width = min(mt9m111->width, rect.width);
> >  	height = min(mt9m111->height, rect.height);
> >
> > -	ret = mt9m111_setup_geometry(mt9m111, &rect, width, height, mt9m111->fmt->code);
> > -	if (!ret) {
> > -		mt9m111->rect = rect;
> > -		mt9m111->width = width;
> > -		mt9m111->height = height;
> > -	}
> > +	mt9m111->rect = rect;
> > +	mt9m111->width = width;
> > +	mt9m111->height = height;
> >
> > -	return ret;
> > +	return 0;
> >  }
> >
> >  static int mt9m111_get_selection(struct v4l2_subdev *sd,
> > @@ -632,7 +629,6 @@ static int mt9m111_set_fmt(struct v4l2_subdev *sd,
> >  	const struct mt9m111_datafmt *fmt;
> >  	struct v4l2_rect *rect = &mt9m111->rect;
> >  	bool bayer;
> > -	int ret;
> >
> >  	if (mt9m111->is_streaming)
> >  		return -EBUSY;
> > @@ -681,16 +677,11 @@ static int mt9m111_set_fmt(struct v4l2_subdev *sd,
> >  		return 0;
> >  	}
> >
> > -	ret = mt9m111_setup_geometry(mt9m111, rect, mf->width, mf->height, mf->code);
> > -	if (!ret)
> > -		ret = mt9m111_set_pixfmt(mt9m111, mf->code);
> > -	if (!ret) {
> > -		mt9m111->width	= mf->width;
> > -		mt9m111->height	= mf->height;
> > -		mt9m111->fmt	= fmt;
> > -	}
> > +	mt9m111->width	= mf->width;
> > +	mt9m111->height	= mf->height;
> > +	mt9m111->fmt	= fmt;
> >
> > -	return ret;
> > +	return 0;
> >  }
> >
> >  static const struct mt9m111_mode_info *
> > @@ -748,6 +739,8 @@ mt9m111_find_mode(struct mt9m111 *mt9m111, unsigned int req_fps,
> >  	return mode;
> >  }
> >
> > +static int mt9m111_s_power(struct v4l2_subdev *sd, int on);
> > +
> >  #ifdef CONFIG_VIDEO_ADV_DEBUG
> >  static int mt9m111_g_register(struct v4l2_subdev *sd,
> >  			      struct v4l2_dbg_register *reg)
> > @@ -758,10 +751,14 @@ static int mt9m111_g_register(struct v4l2_subdev *sd,
> >  	if (reg->reg > 0x2ff)
> >  		return -EINVAL;
> >
> > +	mt9m111_s_power(sd, 1);
> > +
> >  	val = mt9m111_reg_read(client, reg->reg);
> >  	reg->size = 2;
> >  	reg->val = (u64)val;
> >
> > +	mt9m111_s_power(sd, 0);
> > +
> >  	if (reg->val > 0xffff)
> >  		return -EIO;
> >
> > @@ -776,9 +773,13 @@ static int mt9m111_s_register(struct v4l2_subdev *sd,
> >  	if (reg->reg > 0x2ff)
> >  		return -EINVAL;
> >
> > +	mt9m111_s_power(sd, 1);
> > +
> >  	if (mt9m111_reg_write(client, reg->reg, reg->val) < 0)
> >  		return -EIO;
> >
> > +	mt9m111_s_power(sd, 0);
> > +
>
> So far so good
>
> >  	return 0;
> >  }
> >  #endif
> > @@ -891,6 +892,9 @@ static int mt9m111_s_ctrl(struct v4l2_ctrl *ctrl)
> >  	struct mt9m111 *mt9m111 = container_of(ctrl->handler,
> >  					       struct mt9m111, hdl);
> >
> > +	if (!mt9m111->is_streaming)
> > +		return 0;
> > +
>
> If you refuse to set controls if the sensor is not streaming (ie
> powered) which I think it's right, shouldn't you call
> __v4l2_ctrl_handler_setup() at s_stream(1) time to have the controls
> applied ?
>

Oh scratch that, it's in the s_power(1) call path. It's would be nicer
to have runtime_pm, but you already know that :)

Reviewed-by: Jacopo Mondi <jacopo@...ndi.org>

Thanks
   j

> >  	switch (ctrl->id) {
> >  	case V4L2_CID_VFLIP:
> >  		return mt9m111_set_flip(mt9m111, ctrl->val,
> > --
> > 2.30.2
> >