From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8DDC428B501; Tue, 10 Jun 2025 09:52:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749549175; cv=none; b=lCJPiuFpf+207FPaXSNwP4Mc/P5CXGznWI7HQJr74M2K3UlN9nf83yyzOTpnxwAoA0YW6S5kCKpUsfEf7u1yQ/9Vkc9ugDldbjDsunc0K3siTVk/KHnX/2tCkzhjTvlyfx3naeyQhon1bYO5JfbRCNvbF+G+8OKWQBE1BJR5T18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749549175; c=relaxed/simple; bh=Im5GYUCb1sxEGckIaOnAeshf/338KvZJ59zmYw//6eA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=m7sa3u+Y6/607ZqJnIF7/TabN0huglyP9qpT1ORT+VHhSYbScLHf/oW2H7nUXt6YrlRljER92F1TKoEwxTV2n8kijPn3Aj9a5k0p+sMjMDPVEhlKM0Ix5CldXvsruiF/If+eVqEMLg3LiZ8pwhoOZKwsmrzDV2ptTG5S1Y7aEBI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=VYcfkAMM; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="VYcfkAMM" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 214AF169; Tue, 10 Jun 2025 11:52:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1749549163; bh=Im5GYUCb1sxEGckIaOnAeshf/338KvZJ59zmYw//6eA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VYcfkAMMn6K+mvIMMfKStHcleEwEsMpB7hzK4Uas/m9rLyIes7YU38x0/mJedVKBb caB2NaQvYMsZEPK6xmrYorLMaXFrM06ojzRyDabW+HtlAOOCyaWl7YOSDgbGyGGDRW JUC8Rlqi98psv8LRKo/fJIvtHFGGNjRIl9u7t2jY= Date: Tue, 10 Jun 2025 12:52:38 +0300 From: Laurent Pinchart To: Dave Stevenson Cc: Maxime Ripard , Raspberry Pi Kernel Maintenance , Mauro Carvalho Chehab , Florian Fainelli , Broadcom internal kernel review list , Ray Jui , Scott Branden , Sakari Ailus , Hans Verkuil , Jean-Michel Hautbois , Naushir Patuck , linux-media@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: bcm2835-unicam: Remove RGB24 support Message-ID: <20250610095238.GA28428@pendragon.ideasonboard.com> References: <20250606-rpi-unicam-rgb-bgr-fix-v1-1-9930b963f3eb@kernel.org> <20250609003751.GD14545@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Jun 09, 2025 at 03:33:29PM +0100, Dave Stevenson wrote: > On Mon, 9 Jun 2025 at 01:38, Laurent Pinchart wrote: > > 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 ? > > I've lost track of exactly what gets validated along the pipeline. > unicam_video_link_validate [1] looks to ensure that the V4L2 pixel > format and media bus codes match as listed in the table. > > tc358743, adv7604, adv7511, and adv748x are all saying they produce > MEDIA_BUS_FMT_RGB888_1X24 > ov5640 says it produces MEDIA_BUS_FMT_BGR888_1X24. > > Is that an error in the ov5640 driver? If not, then both entries have > to be in the table to support all those drivers. We haven't standardized which media bus code to use for 24-bit RGB on CSI-2, so I'm not surprised drivers didn't get it right :-( The adv7604 and adv7511 shouldn't be relevant here though, as they're not CSI-2 devices. tc358743 and adv748x are relevant. Sakari, which media bus code would you expect ? > Looking at alvium-csi2.c and st-mipid02.c, both mappings are included > there (and RBG888 in the case of alvium). > Unicam's hardware doesn't care about the ordering as it just writes > the incoming data to memory, so having all the sensible mappings > between MEDIA_BUS_FMT_* and V4L2_PIX_FMT_* values makes sense. > > My initial reaction though is that simply removing the entry won't > solve the problem anyway. You won't get a match between the > MEDIA_BUS_FMT_RGB888_1X24 requested by tc358743 and a supported V4L2 > pixel format, so the link_validate will fail. > Swapping either fourcc or code between the two entries would be the > fix I was expecting. > > [1] https://github.com/torvalds/linux/blob/master/drivers/media/platform/broadcom/bcm2835-unicam.c#L2151-L2169 > > > > Fixes: 392cd78d495f ("media: bcm2835-unicam: Add support for CCP2/CSI2 camera interface") > > > Signed-off-by: Maxime Ripard > > > --- > > > 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