[PATCH v4 3/4] media: imx: imx7-media-csi: Relax width constraints for non-8bpp formats

Alexander Stein
2023-04-19T07:07:27Z

The driver unconditionally aligns the image width to multiples of 8
pixels. The real alignment constraint is 8 bytes, as indicated by the
CSI_IMAG_PARA.IMAGE_WIDTH documentation that calls for 8 pixel alignment
for 8bpp formats and 4 pixel alignment for other formats.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
---
Changes in v4:
* Improve commit message
* Simplify walign calculation
* Remove comment on hardware alignment constraints

drivers/media/platform/nxp/imx7-media-csi.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/nxp/imx7-media-csi.c b/drivers/media/platform/nxp/imx7-media-csi.c
index 1315f5743b76f..e6abbfbc5c129 100644
--- a/drivers/media/platform/nxp/imx7-media-csi.c
+++ b/drivers/media/platform/nxp/imx7-media-csi.c
@@ -1146,6 +1146,7 @@ __imx7_csi_video_try_fmt(struct v4l2_pix_format *pixfmt,
struct v4l2_rect *compose)
{
const struct imx7_csi_pixfmt *cc;
+ u32 walign;

if (compose) {
compose->width = pixfmt->width;
@@ -1163,12 +1164,13 @@ __imx7_csi_video_try_fmt(struct v4l2_pix_format *pixfmt,
}

/*
- * Round up width for minimum burst size.
+ * The width alignment is 8 bytes as indicated by the
+ * CSI_IMAG_PARA.IMAGE_WIDTH documentation. Convert it to pixels.
*
- * TODO: Implement configurable stride support, and check what the real
- * hardware alignment constraint on the width is.
+ * TODO: Implement configurable stride support.
*/
- v4l_bound_align_image(&pixfmt->width, 1, 0xffff, 8,
+ walign = 8 * 8 / cc->bpp;
+ v4l_bound_align_image(&pixfmt->width, 1, 0xffff, walign,
&pixfmt->height, 1, 0xffff, 1, 0);

pixfmt->bytesperline = pixfmt->width * cc->bpp / 8;
--
2.34.1