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 751FB26D4F7 for ; Wed, 28 Jan 2026 14:31:24 +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=1769610686; cv=none; b=ff76m2yI7olydMi8cPpNvN3GjWJB2iYhyRSRTDuJ0mzl40kqKZnGkYcxPTYf62EM2hkxYfp2WsYltMG86i8+VDRSvakHwUwy/pIK9R1T2PhU+t7T2N4DOUJiT6FeLRDRigs0AZDFTp2KrTDfJIBsfdVeWyNJw9WL0PzLSuqyVw4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769610686; c=relaxed/simple; bh=BbfxFM8c+zZV6jFhrZFIgkTKht8egaHY7UZljGTtoKc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=F01Z5iIrRr+lOnH1JCySlD8SjCl0Omycd8m7Gv+W52JyW8x5jAgz5kuNN5RWD9V9cM0e/Wn6Kx53iD7hP1s8eEGWZmDBl7BOqftFzSVhzvj4gcDmO+XJPk86efZ7UoMpkLqN5cOK05vti+YOxMCcJRG7M9wYXqcQFEIUwj7mdiI= 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=puDk4Ibq; 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="puDk4Ibq" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id E785BC6F; Wed, 28 Jan 2026 15:30:44 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1769610645; bh=BbfxFM8c+zZV6jFhrZFIgkTKht8egaHY7UZljGTtoKc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=puDk4IbqJ3SRReC0ZdCcCVJ4mPCzRNW+qDy6j8+3V3hvG+UL8GjKB1n9NHkL9q8/Q Ju96SmQu7EaxR31Vb4dIHbUtLwd+Wr44L8JaMEsniO3TOJRBjxoObMD9xHFFlPoceq ka1wO0NB94f2RmRGW3WNfpTsz9M/Jn1z/wqpkRyk= Date: Wed, 28 Jan 2026 16:31:20 +0200 From: Laurent Pinchart To: Tomi Valkeinen Cc: Vishal Sagar , Anatoliy Klymenko , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Michal Simek , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Geert Uytterhoeven , Dmitry Baryshkov , Pekka Paalanen , Dmitry Baryshkov Subject: Re: [PATCH v7 02/11] drm/fourcc: Add DRM_FORMAT_XV15/XV20 Message-ID: <20260128143120.GA3201622@killaraus> References: <20251201-xilinx-formats-v7-0-1e1558adfefc@ideasonboard.com> <20251201-xilinx-formats-v7-2-1e1558adfefc@ideasonboard.com> <20260128122144.GJ2558360@killaraus> 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 Wed, Jan 28, 2026 at 03:53:21PM +0200, Tomi Valkeinen wrote: > On 28/01/2026 14:21, Laurent Pinchart wrote: > > On Mon, Dec 01, 2025 at 02:18:44PM +0200, Tomi Valkeinen wrote: > >> Add two new pixel formats: > >> > >> DRM_FORMAT_XV15 ("XV15") > >> DRM_FORMAT_XV20 ("XV20") > >> > >> The formats are 2 plane 10 bit per component YCbCr, with the XV15 2x2 > >> subsampled whereas XV20 is 2x1 subsampled. > >> > >> Reviewed-by: Dmitry Baryshkov > >> Reviewed-by: Vishal Sagar > >> Signed-off-by: Tomi Valkeinen > >> --- > >> drivers/gpu/drm/drm_fourcc.c | 6 ++++++ > >> include/uapi/drm/drm_fourcc.h | 8 ++++++++ > >> 2 files changed, 14 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c > >> index e662aea9d105..b22ef86428a1 100644 > >> --- a/drivers/gpu/drm/drm_fourcc.c > >> +++ b/drivers/gpu/drm/drm_fourcc.c > >> @@ -381,6 +381,12 @@ const struct drm_format_info *__drm_format_info(u32 format) > >> { .format = DRM_FORMAT_S416, .depth = 0, .num_planes = 3, > >> .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 }, > >> .hsub = 1, .vsub = 1, .is_yuv = true}, > >> + { .format = DRM_FORMAT_XV15, .depth = 0, .num_planes = 2, > >> + .char_per_block = { 4, 8, 0 }, .block_w = { 3, 3, 0 }, .block_h = { 1, 1, 0 }, > >> + .hsub = 2, .vsub = 2, .is_yuv = true }, > > > > Given the horizontal subsampling, don't we have 6 pixels in 8 bytes ? > > No, the hsub is applied first. > > If you look at framebuffer_check() and the called functions, the > calculations for the min_pitch for a 1920 wide XV15 buffer for the > second plane is: > > width = frame_width / hsub > min_pitch = width * char_per_block[plane] / block_w[plane] > > So: > > width = 1920 / 2 = 960 > min_pitch = 960 * 8 / 3 = 2560 Indeed. I was looking at drm_format_info_min_pitch() and missed that it was supposed to be called with the subsampled with. The argument is documented as * @buffer_width: buffer width in pixels which is quite ambiguous. The char_per_block documentation also does not mention subsampling, adding to the confusion. This should be fixed, but as far as this patch is concerned, Reviewed-by: Laurent Pinchart -- Regards, Laurent Pinchart