From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0CFC3C02183 for ; Thu, 16 Jan 2025 08:43:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B9E4010E8FF; Thu, 16 Jan 2025 08:43:48 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="LEeZiJfR"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2E00710E8FC; Thu, 16 Jan 2025 08:43:47 +0000 (UTC) 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" 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