Re: [PATCH v2] media: imx: imx7-media-csi: Fix applying format constraints

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

Am Freitag, 21. Juli 2023, 00:25:43 CEST schrieb Fabio Estevam:
> From: Fabio Estevam <festevam@denx.de>
> 
> v4l_bound_align_image() aligns to a multiple power of 2 of walign, but the
> result only needs to be a multiple of walign.
> 
> This causes a 640x480 sensor that used to report:
> 
> 	Width/Height      : 640/480
> 
> to incorrectly report:
> 
> 	Width/Height      : 768/480
> 
> Fix this problem by doing the correct alignment via clamp_roundup().
> 
> Reported-by: Tim Harvey <tharvey@gateworks.com>
> Fixes: 6f482c4729d9 ("media: imx: imx7-media-csi: Get rid of superfluous
> call to imx7_csi_mbus_fmt_to_pix_fmt") Co-developed-by: Alexander Stein
> <alexander.stein@ew.tq-group.com> Signed-off-by: Alexander Stein
> <alexander.stein@ew.tq-group.com>
> Signed-off-by: Fabio Estevam <festevam@denx.de>
> ---
> Changes since v1:
> - Export clamp_roundup().
> 
>  drivers/media/platform/nxp/imx7-media-csi.c | 4 ++--
>  drivers/media/v4l2-core/v4l2-common.c       | 5 +++--
>  include/media/v4l2-common.h                 | 2 ++
>  3 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/nxp/imx7-media-csi.c
> b/drivers/media/platform/nxp/imx7-media-csi.c index
> 0bd2613b9320..f3c506fc19c4 100644
> --- a/drivers/media/platform/nxp/imx7-media-csi.c
> +++ b/drivers/media/platform/nxp/imx7-media-csi.c
> @@ -1137,8 +1137,8 @@ __imx7_csi_video_try_fmt(struct v4l2_pix_format
> *pixfmt, * TODO: Implement configurable stride support.
>  	 */
>  	walign = 8 * 8 / cc->bpp;
> -	v4l_bound_align_image(&pixfmt->width, 1, 0xffff, walign,
> -			      &pixfmt->height, 1, 0xffff, 1, 0);
> +	pixfmt->width = clamp_roundup(pixfmt->width, 1, 0xffff, walign);
> +	pixfmt->height = clamp_roundup(pixfmt->height, 1, 0xffff, 1);
> 
>  	pixfmt->bytesperline = pixfmt->width * cc->bpp / 8;
>  	pixfmt->sizeimage = pixfmt->bytesperline * pixfmt->height;
> diff --git a/drivers/media/v4l2-core/v4l2-common.c
> b/drivers/media/v4l2-core/v4l2-common.c index bee1535b04d3..3e8c16bcb0f6
> 100644
> --- a/drivers/media/v4l2-core/v4l2-common.c
> +++ b/drivers/media/v4l2-core/v4l2-common.c
> @@ -106,8 +106,8 @@ static unsigned int clamp_align(unsigned int x, unsigned
> int min, return x;
>  }
> 
> -static unsigned int clamp_roundup(unsigned int x, unsigned int min,
> -				   unsigned int max, unsigned int 
alignment)
> +unsigned int clamp_roundup(unsigned int x, unsigned int min,
> +			   unsigned int max, unsigned int alignment)
>  {
>  	x = clamp(x, min, max);
>  	if (alignment)
> @@ -115,6 +115,7 @@ static unsigned int clamp_roundup(unsigned int x,
> unsigned int min,
> 
>  	return x;
>  }
> +EXPORT_SYMBOL(clamp_roundup);
> 
>  void v4l_bound_align_image(u32 *w, unsigned int wmin, unsigned int wmax,
>  			   unsigned int walign,
> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> index d278836fd9cb..7059b99f4afa 100644
> --- a/include/media/v4l2-common.h
> +++ b/include/media/v4l2-common.h
> @@ -521,6 +521,8 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32
> pixelformat, u32 width, u32 height);
>  int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32
> pixelformat, u32 width, u32 height);
> +unsigned int clamp_roundup(unsigned int x, unsigned int min,
> +			   unsigned int max, unsigned int alignment);
> 
>  /**
>   * v4l2_get_link_freq - Get link rate from transmitter

I expect this to work, but I'm not so sure about exporting clamp_roundup().
I would rather use v4l2_apply_frmsize_constraints() instead, but this requires 
additional work, refer to the TODO in imx7_csi_video_enum_framesizes().
See also my first (broken) try in [1].

As a short term fix, using clamp_roundup() is okay to me. But I'm thinking 
about using a copy of clamp_roundup() as in v1 instead,so to avoid an eventual 
unexport of clamp_roundup in the future. Maybe this concern doesn't matter, I 
guess the maintainers can tell.

Best regards,
Alexander

[1] https://lore.kernel.org/linux-media/202307210050.s7hfCvwG-lkp@intel.com/T/
#ma88811098cb96f3698a8248d903f0c3455febec7

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