On Mon Mar 9 16:07:41 2026 +0100, Maxime Ripard wrote:
> The Unicam driver is a MIPI-CSI2 Receiver, that can capture RGB 4:4:4,
> YCbCr 4:2:2, and raw formats.
>
> RGB 4:4:4 is converted to the MIPI-CSI2 RGB888 video format, and
> associated to the MEDIA_BUS_FMT_RGB888_1X24 media bus code.
>
> However, V4L2_PIX_FMT_RGB24 is defined as having its color components in
> the R, G and B order, from left to right. MIPI-CSI2 however defines the
> RGB888 format with blue first, and that's what MEDIA_BUS_FMT_RGB888_1X24
> defines too.
>
> This essentially means that the R and B will be swapped compared to what
> V4L2_PIX_FMT_RGB24 defines. The same situation occurs with
> V4L2_PIX_FMT_BGR24 being associated to MEDIA_BUS_FMT_BGR888_1X24.
>
> In order to fix the swapped components, we need to change the
> association of V4L2_PIX_FMT_BGR24 to MEDIA_BUS_FMT_RGB888_1X24, and of
> V4L2_PIX_FMT_RGB24 to MEDIA_BUS_FMT_BGR888_1X24.
>
> Since the media bus code is exposed to userspace, and validated by
> unicam's link_validate implementation, we need to explicitly accept (and
> warn) the old association still to preserve backward compatibility.
>
> Signed-off-by: Maxime Ripard <[email protected]>
> Reviewed-by: Laurent Pinchart <[email protected]>
> Signed-off-by: Sakari Ailus <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/platform/broadcom/bcm2835-unicam.c | 41 ++++++++++++++++++------
1 file changed, 32 insertions(+), 9 deletions(-)
---
diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c
b/drivers/media/platform/broadcom/bcm2835-unicam.c
index f0a41f147dfe..8d28ba0b59a3 100644
--- a/drivers/media/platform/broadcom/bcm2835-unicam.c
+++ b/drivers/media/platform/broadcom/bcm2835-unicam.c
@@ -338,12 +338,12 @@ static const struct unicam_format_info
unicam_image_formats[] = {
.csi_dt = MIPI_CSI2_DT_RGB565,
}, {
.fourcc = V4L2_PIX_FMT_RGB24, /* rgb */
- .code = MEDIA_BUS_FMT_RGB888_1X24,
+ .code = MEDIA_BUS_FMT_BGR888_1X24,
.depth = 24,
.csi_dt = MIPI_CSI2_DT_RGB888,
}, {
.fourcc = V4L2_PIX_FMT_BGR24, /* bgr */
- .code = MEDIA_BUS_FMT_BGR888_1X24,
+ .code = MEDIA_BUS_FMT_RGB888_1X24,
.depth = 24,
.csi_dt = MIPI_CSI2_DT_RGB888,
}, {
@@ -2144,22 +2144,45 @@ static int unicam_video_link_validate(struct media_link
*link)
const struct v4l2_pix_format *fmt = &node->fmt.fmt.pix;
const struct unicam_format_info *fmtinfo;
- fmtinfo = unicam_find_format_by_fourcc(fmt->pixelformat,
-
UNICAM_SD_PAD_SOURCE_IMAGE);
+ fmtinfo = unicam_find_format_by_code(format->code,
+
UNICAM_SD_PAD_SOURCE_IMAGE);
if (WARN_ON(!fmtinfo)) {
ret = -EPIPE;
goto out;
}
- if (fmtinfo->code != format->code ||
- fmt->height != format->height ||
+ /*
+ * Unicam initially associated BGR24 to BGR888_1X24 and RGB24 to
+ * RGB888_1X24.
+ *
+ * In order to allow the applications using the old behaviour to
+ * run, let's accept the old combination, but warn about it.
+ */
+ if (fmtinfo->fourcc != fmt->pixelformat) {
+ if ((fmt->pixelformat == V4L2_PIX_FMT_BGR24 &&
+ format->code == MEDIA_BUS_FMT_BGR888_1X24) ||
+ (fmt->pixelformat == V4L2_PIX_FMT_RGB24 &&
+ format->code == MEDIA_BUS_FMT_RGB888_1X24)) {
+ dev_warn_once(node->dev->dev,
+ "Incorrect pixel format %p4cc for
0x%04x. Fix your application to use %p4cc.\n",
+ &fmt->pixelformat, format->code,
&fmtinfo->fourcc);
+ } else {
+ dev_dbg(node->dev->dev,
+ "image: format mismatch: 0x%04x <=>
%p4cc\n",
+ format->code, &fmt->pixelformat);
+ ret = -EPIPE;
+ goto out;
+ }
+ }
+
+ if (fmt->height != format->height ||
fmt->width != format->width ||
fmt->field != format->field) {
dev_dbg(node->dev->dev,
- "image: (%u x %u) 0x%08x %s != (%u x %u) 0x%08x
%s\n",
- fmt->width, fmt->height, fmtinfo->code,
+ "image: (%u x %u) %s != (%u x %u) %s\n",
+ fmt->width, fmt->height,
v4l2_field_names[fmt->field],
- format->width, format->height, format->code,
+ format->width, format->height,
v4l2_field_names[format->field]);
ret = -EPIPE;
}
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