Re: [PATCH] media: bcm2835-unicam: Remove RGB24 support
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: 2025-06-09 00:38:04
Also in:
linux-media, lkml
Hi Maxime, Thank you for the patch. On Fri, Jun 06, 2025 at 04:53:03PM +0200, Maxime Ripard wrote:
The RGB24 V4L2 format is defined as a pixel format with 8 bits per components, with the components being in the red, green, and blue order from left to right. The RGB MIPI-CSI2 is defined in the specification (Section 11.3.1, RGB888) with blue coming first, then green, then red. So the opposite of what V4L2 means by RGB. Since the hardware cannot reorder the components, this means that when selecting the RGB24 format, you get inverted red and blue components compared to what you'd expect. The driver already supports BGR24, so we can simply remove the RGB24 format from the driver.
The only reason I could think of to explain why the driver exposes V4L2_PIX_FMT_RGB24 is to support CSI-2 sources that transfer RGB888 data with a non-standard order. I don't know what hardware would do that. Dave, Naush, do you recall why this pixel format is supported by the unicam driver ?
quoted hunk ↗ jump to hunk
Fixes: 392cd78d495f ("media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface") Signed-off-by: Maxime Ripard <mripard@kernel.org> --- drivers/media/platform/broadcom/bcm2835-unicam.c | 5 ----- 1 file changed, 5 deletions(-)diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c b/drivers/media/platform/broadcom/bcm2835-unicam.c index f10064107d543caf867249d0566a0f42d6d8c4c6..1f549019efd53c9aae83193e74f1a3601ebf274d 100644 --- a/drivers/media/platform/broadcom/bcm2835-unicam.c +++ b/drivers/media/platform/broadcom/bcm2835-unicam.c@@ -338,15 +338,10 @@ static const struct unicam_format_info unicam_image_formats[] = { /* RGB Formats */ .fourcc = V4L2_PIX_FMT_RGB565, /* gggbbbbb rrrrrggg */ .code = MEDIA_BUS_FMT_RGB565_1X16, .depth = 16, .csi_dt = MIPI_CSI2_DT_RGB565, - }, { - .fourcc = V4L2_PIX_FMT_RGB24, /* rgb */ - .code = MEDIA_BUS_FMT_RGB888_1X24, - .depth = 24, - .csi_dt = MIPI_CSI2_DT_RGB888, }, { .fourcc = V4L2_PIX_FMT_BGR24, /* bgr */ .code = MEDIA_BUS_FMT_BGR888_1X24, .depth = 24, .csi_dt = MIPI_CSI2_DT_RGB888,--- base-commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca change-id: 20250606-rpi-unicam-rgb-bgr-fix-d1b6f46a75ad
-- Regards, Laurent Pinchart