Re: [PATCH] rcar-csi2: Allow configuring of video standard

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Niklas,

On Thu, Mar 07, 2019 at 01:22:36AM +0100, Niklas Söderlund wrote:
> On 2019-03-07 02:13:18 +0200, Laurent Pinchart wrote:
> > On Sat, Feb 16, 2019 at 11:57:58PM +0100, Niklas Söderlund wrote:
> >> Allow the hardware to to do proper field detection for interlaced field
> >> formats by implementing s_std() and g_std(). Depending on which video
> >> standard is selected the driver needs to setup the hardware to correctly
> >> identify fields.
> > 
> > I don't think this belongs to the CSI-2 receiver. Standards are really
> > an analog concept, and should be handled by the analog front-end. At the
> > CSI-2 level there's no concept of analog standard anymore.
> 
> I agree it should be handled by the analog front-end. This is patch just 
> lets the user propagate the information in the pipeline. The driver 
> could instead find its source subdevice in the media graph and ask which 
> standard it's supplying.
> 
> I wrestled a bit with this and went with this approach as it then works 
> the same as with other format information, such as dimensions and pixel 
> format. If the driver acquires the standard by itself why should it no 
> the same for the format? I'm willing to change this but I would like to 
> understand where the divider for format propagating in kernel and 
> user-space is :-)
> 
> Also what if there are subdevices between rcar-csi2 and the analog 
> front-end which do not support the g_std operation?

My point is that the analog standard shouldn't be propagated at all,
neither inside the kernel nor in userspace, as it is not applicable to
CSI-2.

> >> Later versions of the datasheet have also been updated to make it clear
> >> that FLD register should be set to 0 when dealing with none interlaced
> >> field formats.
> >> 
> >> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> >> ---
> >>  drivers/media/platform/rcar-vin/rcar-csi2.c | 33 +++++++++++++++++++--
> >>  1 file changed, 30 insertions(+), 3 deletions(-)
> >> 
> >> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> >> index f3099f3e536d808a..664d3784be2b9db9 100644
> >> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> >> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> >> @@ -361,6 +361,7 @@ struct rcar_csi2 {
> >>  	struct v4l2_subdev *remote;
> >>  
> >>  	struct v4l2_mbus_framefmt mf;
> >> +	v4l2_std_id std;
> >>  
> >>  	struct mutex lock;
> >>  	int stream_count;
> >> @@ -389,6 +390,22 @@ static void rcsi2_write(struct rcar_csi2 *priv, unsigned int reg, u32 data)
> >>  	iowrite32(data, priv->base + reg);
> >>  }
> >>  
> >> +static int rcsi2_s_std(struct v4l2_subdev *sd, v4l2_std_id std)
> >> +{
> >> +	struct rcar_csi2 *priv = sd_to_csi2(sd);
> >> +
> >> +	priv->std = std;
> >> +	return 0;
> >> +}
> >> +
> >> +static int rcsi2_g_std(struct v4l2_subdev *sd, v4l2_std_id *std)
> >> +{
> >> +	struct rcar_csi2 *priv = sd_to_csi2(sd);
> >> +
> >> +	*std = priv->std;
> >> +	return 0;
> >> +}
> >> +
> >>  static void rcsi2_standby_mode(struct rcar_csi2 *priv, int on)
> >>  {
> >>  	if (!on) {
> >> @@ -475,7 +492,7 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp)
> >>  static int rcsi2_start_receiver(struct rcar_csi2 *priv)
> >>  {
> >>  	const struct rcar_csi2_format *format;
> >> -	u32 phycnt, vcdt = 0, vcdt2 = 0;
> >> +	u32 phycnt, vcdt = 0, vcdt2 = 0, fld = 0;
> >>  	unsigned int i;
> >>  	int mbps, ret;
> >>  
> >> @@ -507,6 +524,15 @@ static int rcsi2_start_receiver(struct rcar_csi2 *priv)
> >>  			vcdt2 |= vcdt_part << ((i % 2) * 16);
> >>  	}
> >>  
> >> +	if (priv->mf.field != V4L2_FIELD_NONE) {
> >> +		fld =  FLD_FLD_EN4 | FLD_FLD_EN3 | FLD_FLD_EN2 | FLD_FLD_EN;
> >> +
> >> +		if (priv->std & V4L2_STD_525_60)
> >> +			fld |= FLD_FLD_NUM(2);
> >> +		else
> >> +			fld |= FLD_FLD_NUM(1);
> >> +	}
> >> +
> >>  	phycnt = PHYCNT_ENABLECLK;
> >>  	phycnt |= (1 << priv->lanes) - 1;
> >>  
> >> @@ -519,8 +545,7 @@ static int rcsi2_start_receiver(struct rcar_csi2 *priv)
> >>  	rcsi2_write(priv, PHTC_REG, 0);
> >>  
> >>  	/* Configure */
> >> -	rcsi2_write(priv, FLD_REG, FLD_FLD_NUM(2) | FLD_FLD_EN4 |
> >> -		    FLD_FLD_EN3 | FLD_FLD_EN2 | FLD_FLD_EN);
> >> +	rcsi2_write(priv, FLD_REG, fld);
> >>  	rcsi2_write(priv, VCDT_REG, vcdt);
> >>  	if (vcdt2)
> >>  		rcsi2_write(priv, VCDT2_REG, vcdt2);
> >> @@ -662,6 +687,8 @@ static int rcsi2_get_pad_format(struct v4l2_subdev *sd,
> >>  }
> >>  
> >>  static const struct v4l2_subdev_video_ops rcar_csi2_video_ops = {
> >> +	.s_std = rcsi2_s_std,
> >> +	.g_std = rcsi2_g_std,
> >>  	.s_stream = rcsi2_s_stream,
> >>  };
> >>  

-- 
Regards,

Laurent Pinchart