Re: [PATCH v2 1/3] media: imx: imx7-media-csi: Get rid of superfluous call to imx7_csi_mbus_fmt_to_pix_fmt

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

Hi Alexander,

On Tue, Apr 18, 2023 at 12:00:43PM +0200, Alexander Stein wrote:
> Am Dienstag, 18. April 2023, 11:27:13 CEST schrieb Laurent Pinchart:
> > On Tue, Apr 18, 2023 at 09:14:37AM +0200, Alexander Stein wrote:
> > > There is no need to convert input pixformat to mbus_framefmt and back
> > > again. Instead apply pixformat width contrains directly.
> > > 
> > > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > > ---
> > > 
> > >  drivers/media/platform/nxp/imx7-media-csi.c | 14 +++++++++-----
> > >  1 file changed, 9 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/media/platform/nxp/imx7-media-csi.c
> > > b/drivers/media/platform/nxp/imx7-media-csi.c index
> > > b701e823436a8..bd649fd9166fd 100644
> > > --- a/drivers/media/platform/nxp/imx7-media-csi.c
> > > +++ b/drivers/media/platform/nxp/imx7-media-csi.c
> > > @@ -1145,8 +1145,8 @@ static const struct imx7_csi_pixfmt *
> > >  __imx7_csi_video_try_fmt(struct v4l2_pix_format *pixfmt,
> > >  			 struct v4l2_rect *compose)
> > >  {
> > > -	struct v4l2_mbus_framefmt fmt_src;
> > >  	const struct imx7_csi_pixfmt *cc;
> > > +	u32 stride;
> > > 
> > >  	/*
> > >  	 * Find the pixel format, default to the first supported format if not
> > > @@ -1172,12 +1172,16 @@ __imx7_csi_video_try_fmt(struct v4l2_pix_format *pixfmt,
> > >  		}
> > >  	}
> > > 
> > > -	v4l2_fill_mbus_format(&fmt_src, pixfmt, 0);
> > > -	imx7_csi_mbus_fmt_to_pix_fmt(pixfmt, &fmt_src, cc);
> > 
> > Could you please keep the comment from imx7_csi_mbus_fmt_to_pix_fmt()
> > here, to indicate where the alignment comes from ?
> 
> Sure, why not.
> 
> > 	/* Round up width for minimum burst size */
> > 
> > We should likely revisit this in the future, I don't think the alignment
> > is actually needed. This could be recorded already:
> > 
> > 	/*
> > 	 * Round up width for minimum burst size.
> > 	 *
> > 	 * TODO: Implement configurable stride support, and check what the real
> > 	 * hardware alignment constraint on the width is.
> > 	 */
> 
> Sounds good. I was already suspecting actual stride support is not supported, 
> as FBUF_PARA is set to 0 (in non-interlaced mode).
> 
> > > +	v4l_bound_align_image(&pixfmt->width, 1, 0xffff, 8,
> > > +			      &pixfmt->height, 1, 0xffff, 1, 0);
> > > +
> > > +	stride = round_up((pixfmt->width * cc->bpp) / 8, 8);
> > 
> > You can drop the round_up(), as pixfmt->width is now a multiple of 8, so
> > 
> > 	pixfmt->bytesperline = pixfmt->width * cc->bpp / 8;
> 
> But that is only identical if cc->bpp == 8, or am I missing something here?

If cc->bpp is equal to 16, you will get

 	pixfmt->bytesperline = pixfmt->width * 2;

which will still be a multiple of 8 as width is a multiple of 8.

> > > +	pixfmt->bytesperline = stride;
> > > +	pixfmt->sizeimage = stride * pixfmt->height;
> > > 
> > >  	if (compose) {
> > > 
> > > -		compose->width = fmt_src.width;
> > > -		compose->height = fmt_src.height;
> > > +		compose->width = pixfmt->width;
> > 
> > This is a change of behaviour, compose->width used to be set to the
> > unaligned width.
> 
> Oh, you are right. I'll fix that.
> 
> > > +		compose->height = pixfmt->height;
> > > 
> > >  	}
> > >  	
> > >  	return cc;

-- 
Regards,

Laurent Pinchart

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