Re: Re: [PATCH 14/19] media: i2c: imx290: Implement HBLANK and VBLANK controls

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Laurent,

Am Donnerstag, 21. Juli 2022, 13:17:21 CEST schrieb Laurent Pinchart:
> Hi Alexander,
> 
> On Thu, Jul 21, 2022 at 12:05:46PM +0200, Alexander Stein wrote:
> > Am Donnerstag, 21. Juli 2022, 10:35:35 CEST schrieb Laurent Pinchart:
> > > Add support for the V4L2_CID_HBLANK and V4L2_CID_VBLANK controls to the
> > > imx290 driver. Make the controls read-only to start with, to report the
> > > values to userspace for timing calculation.
> > > 
> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > ---
> > > 
> > >  drivers/media/i2c/imx290.c | 39 +++++++++++++++++++++++++++++++++++++-
> > >  1 file changed, 38 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> > > index 4408dd3e191f..7190399f4111 100644
> > > --- a/drivers/media/i2c/imx290.c
> > > +++ b/drivers/media/i2c/imx290.c
> > > @@ -146,6 +146,8 @@ struct imx290 {
> > > 
> > >  	struct v4l2_ctrl_handler ctrls;
> > >  	struct v4l2_ctrl *link_freq;
> > >  	struct v4l2_ctrl *pixel_rate;
> > > 
> > > +	struct v4l2_ctrl *hblank;
> > > +	struct v4l2_ctrl *vblank;
> > > 
> > >  	struct mutex lock;
> > >  
> > >  };
> > > 
> > > @@ -642,6 +644,20 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
> > > 
> > >  		if (imx290->pixel_rate)
> > >  		
> > >  			__v4l2_ctrl_s_ctrl_int64(imx290->pixel_rate,
> > >  			
> > >  						 
imx290_calc_pixel_rate(imx290));
> > > 
> > > +
> > > +		if (imx290->hblank) {
> > > +			unsigned int hblank = mode->hmax - mode-
>width;
> > > +
> > > +			__v4l2_ctrl_modify_range(imx290->hblank, 
hblank, hblank,
> > > +						 1, hblank);
> > > +		}
> > > +
> > > +		if (imx290->vblank) {
> > > +			unsigned int vblank = IMX290_VMAX_DEFAULT - 
mode->height;
> > > +
> > > +			__v4l2_ctrl_modify_range(imx290->vblank, 
vblank, vblank,
> > > +						 1, vblank);
> > > +		}
> > > 
> > >  	}
> > >  	
> > >  	*format = fmt->format;
> > > 
> > > @@ -880,9 +896,10 @@ static const struct media_entity_operations
> > > imx290_subdev_entity_ops = {> > 
> > >  static int imx290_ctrl_init(struct imx290 *imx290)
> > >  {
> > > 
> > > +	unsigned int blank;
> > > 
> > >  	int ret;
> > > 
> > > -	v4l2_ctrl_handler_init(&imx290->ctrls, 5);
> > > +	v4l2_ctrl_handler_init(&imx290->ctrls, 7);
> > > 
> > >  	imx290->ctrls.lock = &imx290->lock;
> > >  	
> > >  	v4l2_ctrl_new_std(&imx290->ctrls, &imx290_ctrl_ops,
> > > 
> > > @@ -910,6 +927,26 @@ static int imx290_ctrl_init(struct imx290 *imx290)
> > > 
> > >  				     
ARRAY_SIZE(imx290_test_pattern_menu) - 1,
> > >  				     0, 0, 
imx290_test_pattern_menu);
> > > 
> > > +	/*
> > > +	 * Horizontal blanking is controlled through the HMAX register, 
which
> > > +	 * contains a line length in INCK clock units. The INCK frequency 
is
> > > +	 * fixed to 74.25 MHz. The HMAX value is currently fixed to 1100,
> > > +	 * convert it to a number of pixels based on the nominal pixel 
rate.
> > > +	 */
> > 
> > Currently the driver only supports 37.125 MHz, please refer to
> > imx290_probe.
> Indeed. Re-reading the comment, I suspect something is wrong, as hmax is
> not converted to pixels here (and is also not fixed to 1100). The only
> datasheet I found that is publicly accessed doesn't explain very clearly
> how the HMAX value should be computed. Based on your experience with IMX
> sensors, would you be able to shed some light on this ?

Can you share the link to this datasheet you found?
Sorry, my experience is more like try and error. I don't fully understand this 
as well, but apparently this depends on frame rate select (FRSEL).

Best regards,
Alexander

> > > +	blank = imx290->current_mode->hmax - imx290->current_mode->width;
> > > +	imx290->hblank = v4l2_ctrl_new_std(&imx290->ctrls, 
&imx290_ctrl_ops,
> > > +					   V4L2_CID_HBLANK, 
blank, blank, 1,
> > > +					   blank);
> > > +	if (imx290->hblank)
> > > +		imx290->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > > +
> > > +	blank = IMX290_VMAX_DEFAULT - imx290->current_mode->height;
> > > +	imx290->vblank = v4l2_ctrl_new_std(&imx290->ctrls, 
&imx290_ctrl_ops,
> > > +					   V4L2_CID_VBLANK, 
blank, blank, 1,
> > > +					   blank);
> > > +	if (imx290->vblank)
> > > +		imx290->vblank->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> > > +
> > > 
> > >  	imx290->sd.ctrl_handler = &imx290->ctrls;
> > >  	
> > >  	if (imx290->ctrls.error) {