Re: [PATCH 01/11] media: rcar-vin: Fix YUYV8_1X16 handling for CSI-2

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

Hello,

On 2024-05-05 23:50:43 +0300, Laurent Pinchart wrote:
> Hi Jacopo,
> 
> Thank you for the patch.
> 
> On Fri, May 03, 2024 at 05:51:16PM +0200, Jacopo Mondi wrote:
> > The YUYV8_1X16 and UYVY8_1X16 formats are treated as 'ITU-R
> > BT.601/BT.1358 16-bit YCbCr-422 input' (YUV16 - 0x5) in the R-Car VIN
> > driver and are thus disallowed when capturing frames from the R-Car
> > CSI-2 interface according to the hardware manual.
> > 
> > As the 1X16 format variants are meant to be used with serial busses they
> > have to be treated as 'YCbCr-422 8-bit data input' (0x1) when capturing
> > from CSI-2, which is a valid setting for CSI-2.
> > 
> > Commit 78b3f9d75a62 ("media: rcar-vin: Add check that input interface
> > and format are valid") disallowed capturing YUV16 when using the CSI-2
> > interface. Fix this by using YUV8_BT601 for YCbCr422 when CSI-2 is in
> > use.
> > 
> > Fixes: 78b3f9d75a62 ("media: rcar-vin: Add check that input interface and format are valid")
> > Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> > ---
> >  .../media/platform/renesas/rcar-vin/rcar-dma.c   | 16 +++++++++++++---
> >  1 file changed, 13 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/media/platform/renesas/rcar-vin/rcar-dma.c b/drivers/media/platform/renesas/rcar-vin/rcar-dma.c
> > index e2c40abc6d3d..21d5b2815e86 100644
> > --- a/drivers/media/platform/renesas/rcar-vin/rcar-dma.c
> > +++ b/drivers/media/platform/renesas/rcar-vin/rcar-dma.c
> > @@ -742,12 +742,22 @@ static int rvin_setup(struct rvin_dev *vin)
> >  	 */
> >  	switch (vin->mbus_code) {
> >  	case MEDIA_BUS_FMT_YUYV8_1X16:
> > -		/* BT.601/BT.1358 16bit YCbCr422 */
> > -		vnmc |= VNMC_INF_YUV16;
> > +		if (vin->is_csi)
> > +			/* YCbCr422 8-bit */
> > +			vnmc |= VNMC_INF_YUV8_BT601;
> > +		else
> > +			/* BT.601/BT.1358 16bit YCbCr422 */
> > +			vnmc |= VNMC_INF_YUV16;
> >  		input_is_yuv = true;
> >  		break;
> >  	case MEDIA_BUS_FMT_UYVY8_1X16:
> > -		vnmc |= VNMC_INF_YUV16 | VNMC_YCAL;
> > +		if (vin->is_csi)
> > +			/* YCbCr422 8-bit */
> > +			vnmc |= VNMC_INF_YUV8_BT601;
> > +		else
> > +			/* BT.601/BT.1358 16bit YCbCr422 */
> > +			vnmc |= VNMC_INF_YUV16;
> > +		vnmc |= VNMC_YCAL;
> 
> You could also write
> 
> 	case MEDIA_BUS_FMT_UYVY8_1X16:
> 		vnmc |= VNMC_YCAL;
> 		fallthrough;
> 	case MEDIA_BUS_FMT_YUYV8_1X16:
> 		if (vin->is_csi)
> 			/* YCbCr422 8-bit */
> 			vnmc |= VNMC_INF_YUV8_BT601;
> 		else
> 			/* BT.601/BT.1358 16bit YCbCr422 */
> 			vnmc |= VNMC_INF_YUV16;
> 		input_is_yuv = true;
> 		break;
> 
> Up to you.

I prefers Jacopo's version. This function should likely be reworked in 
the future to be separate Gen2/Gen3/Gen4 versions so we can remove all 
these ugly checks as not all formats are supported on all hardware 
generations.

I think that work would be easier if we keep the current ugly and dumb 
structure of these switches.

> 
> On a side note, CSI-2 isn't supposed to support
> MEDIA_BUS_FMT_YUYV8_1X16. The native format is MEDIA_BUS_FMT_UYVY8_1X16.
> I wonder if we should trim down the list of supported formats. That's a
> candidate for another patch though.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> 
> >  		input_is_yuv = true;
> >  		break;
> >  	case MEDIA_BUS_FMT_UYVY8_2X8:
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Kind Regards,
Niklas Söderlund