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 6278B1C5F11; Thu, 16 Jan 2025 08:43:53 +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=1737017034; cv=none; b=kqh1HHPygKPc3Vr2yJaUjjYTWAirc79CdXUcyNosLzi0gJizOBvxUKZbOcGB/MFyGfyE/+kK73yTxhHaDUgC2+uj9x6WB6UnQtU+jznpeJK4j81YM85V6o/oK64CTBof9PIfFGur8XWXEXuGb5/hqNFujVoM8Fau3WJ+Q7DYwsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737017034; c=relaxed/simple; bh=YBJYqGqQ2U3g/glMhqBtVA7c9PNcNKm2bF2hwWN3X/8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=osWWPrdAO6iqZ6i9HBTI7MXGNRey7UcgmmScM9gB7etYLnxvqpY2Ak3b62Acf8j6+O4f3c4DfApKxVblSsC9L1GeLGExTIYMrSuBP8VmlhWOZoxVNwrCmK+QL1cVDekJakVDl1eYhrxE53RhwFx0TgS2mBun+LUYgMN6h0+ihRI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=LEeZiJfR; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="LEeZiJfR" Received: from pendragon.ideasonboard.com (unknown [193.209.96.36]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 1CDD7169; Thu, 16 Jan 2025 09:42:47 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1737016967; bh=YBJYqGqQ2U3g/glMhqBtVA7c9PNcNKm2bF2hwWN3X/8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LEeZiJfRiaftp5JL3OuhSGJ31fbSk67YMrTfIULuryGPguJN8dhwOq+oPh23KD4oZ oDgG9Q7qiklC025s5e31jn5W8DZrWY3XLnKdac3TlZaKlReDu0jJF+McdlL4rZbfey vio2zbz4p7HYes9E+SH0Bj1kP+VRYA2cki8/bjIo= Date: Thu, 16 Jan 2025 10:43:40 +0200 From: Laurent Pinchart To: Daniel Stone Cc: Tomi Valkeinen , Thomas Zimmermann , maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@gmail.com, simona@ffwll.ch, dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, imx@lists.linux.dev, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, virtualization@lists.linux.dev, spice-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-tegra@vger.kernel.org, intel-xe@lists.freedesktop.org, xen-devel@lists.xenproject.org, Andy Yan Subject: Re: [PATCH v2 25/25] drm/xlnx: Compute dumb-buffer sizes with drm_mode_size_dumb() Message-ID: <20250116084340.GF6754@pendragon.ideasonboard.com> References: <0ea6be58-0e04-4172-87cd-064a3e4a43bc@suse.de> <4af0b6a7-c16a-4187-bbf5-365a9c86de21@suse.de> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev 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 15, 2025 at 02:34:26PM +0000, Daniel Stone wrote: > On Wed, 15 Jan 2025 at 14:20, Tomi Valkeinen wrote: > > No disagreement there, we need CREATE_DUMB2. > > > > My point is that we have the current UAPI, and we have userspace using > > it, but we don't have clear rules what the ioctl does with specific > > parameters, and we don't document how it has to be used. > > > > Perhaps the situation is bad, and all we can really say is that > > CREATE_DUMB only works for use with simple RGB formats, and the behavior > > for all other formats is platform specific. But I think even that would > > be valuable in the UAPI docs. > > Yeah, CREATE_DUMB only works for use with simple RGB formats in a > linear layout. Not monochrome or YUV or tiled or displayed rotated or > whatever. > > If it happens to accidentally work for other uses, that's fine, but > it's not generically reliable for anything other than simple linear > RGB. It's intended to let you do splash screens, consoles, recovery > password entries, and software-rendered compositors if you really > want. Anything more than that isn't 'dumb'. We have lots of software out there that rely on CREATE_DUMB supporting YUV linear formats, and lots of drivers (mostly on Arm I suppose) that implement YUV support in CREATE_DUMB. I'm fine replacing it with something better, but I think we need a standard ioctl that can create linear YUV buffers. I've been told many times that DRM doesn't want to standardize buffer allocation further than what CREATE_DUMB is made for. Can we reconsider this rule then ? -- Regards, Laurent Pinchart