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 05CC4C021A4 for ; Mon, 24 Feb 2025 14:00:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7FD5610E403; Mon, 24 Feb 2025 14:00:55 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="Ou8YPowB"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) by gabe.freedesktop.org (Postfix) with ESMTPS id 45A1D10E3BC for ; Mon, 24 Feb 2025 14:00:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1740405654; x=1771941654; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=7Z65X3uAnnrMTsxGFkCu0G6zCm18r0qbQoTUv+3XTJY=; b=Ou8YPowB6seSB49nO3PQx3mWh0CgR/Etcnx2goIWZA7hKCSnaVshCkTF 3HumsUxAl47JShqIHAzctatYStcOXUwcbYvLckg4NX+XmIGnMnDSyQcMl Y6oyj/XJiSlTfox3CPjHn2f/WE92oakxQsmeGFMWfGMD20wyoZ6FxgtNg bjT6Cyb1zfYkO8MF2lDwPTD8OepJpUNJtewIn0MDypa8ydE9bGCDoj4MS HKg9Nf6XjipoNdLFzrSAs+6rwum1SNqTQJzMpSxMBx/eLlHXsHDnkQ3N0 Xy2EopVPWUHuI3DFNvgG1/Alqbm9Qjju6jO4NL5IvdKwVxj2gl4rSniIg Q==; X-CSE-ConnectionGUID: NcoZPEauS2qrnq5WYpGRbA== X-CSE-MsgGUID: tg1ZVbQeRBinFi9f+FIlKg== X-IronPort-AV: E=McAfee;i="6700,10204,11355"; a="58576175" X-IronPort-AV: E=Sophos;i="6.13,309,1732608000"; d="scan'208";a="58576175" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Feb 2025 06:00:54 -0800 X-CSE-ConnectionGUID: omwNZuk9RwmIZq4cQKjXWA== X-CSE-MsgGUID: 8k+fUmvKS+K3SkL+2y59lg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.13,309,1732608000"; d="scan'208";a="116270717" Received: from smile.fi.intel.com ([10.237.72.58]) by fmviesa008.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Feb 2025 06:00:51 -0800 Received: from andy by smile.fi.intel.com with local (Exim 4.98) (envelope-from ) id 1tmZ0q-0000000EiFx-1f8o; Mon, 24 Feb 2025 16:00:48 +0200 Date: Mon, 24 Feb 2025 16:00:48 +0200 From: "andriy.shevchenko@linux.intel.com" To: Aditya Garg Cc: "maarten.lankhorst@linux.intel.com" , "mripard@kernel.org" , "tzimmermann@suse.de" , "airlied@gmail.com" , "simona@ffwll.ch" , Kerem Karabay , Atharva Tiwari , Aun-Ali Zaidi , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" Subject: Re: [PATCH v4 2/2] drm/tiny: add driver for Apple Touch Bars in x86 Macs Message-ID: References: <844C1D39-4891-4DC2-8458-F46FA1B59FA0@live.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <844C1D39-4891-4DC2-8458-F46FA1B59FA0@live.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Feb 24, 2025 at 01:40:20PM +0000, Aditya Garg wrote: > From: Kerem Karabay > > The Touch Bars found on x86 Macs support two USB configurations: one > where the device presents itself as a HID keyboard and can display > predefined sets of keys, and one where the operating system has full > control over what is displayed. > > This commit adds support for the display functionality of the second > configuration. Functionality for the first configuration has been > merged in the HID tree. > > Note that this driver has only been tested on T2 Macs, and only includes > the USB device ID for these devices. Testing on T1 Macs would be > appreciated. > > Credit goes to Ben (Bingxing) Wang on GitHub for reverse engineering > most of the protocol. > > Also, as requested by Andy, I would like to clarify the use of __packed > structs in this driver: > > - All the packed structs are aligned except for appletbdrm_msg_information. > - We have to pack appletbdrm_msg_information since it is requirement of > the protocol. > - We compared binaries compiled by keeping the rest structs __packed and > not __packed using bloat-o-meter, and __packed was not affecting code > generation. > - To maintain consistency, rest structs have been kept __packed. ... > +#define __APPLETBDRM_MSG_STR4(str4) ((__le32 __force)((str4[0] << 24) | (str4[1] << 16) | (str4[2] << 8) | str4[3])) As commented previously this is quite strange what's going on with endianess in this driver. Especially the above weirdness when get_unaligned_be32() is being open coded and force-cast to __le32. ... > +struct appletbdrm_msg_information { > + struct appletbdrm_msg_response_header header; > + u8 unk_14[12]; > + __le32 width; > + __le32 height; > + u8 bits_per_pixel; > + __le32 bytes_per_row; > + __le32 orientation; > + __le32 bitmap_info; > + __le32 pixel_format; > + __le32 width_inches; /* floating point */ > + __le32 height_inches; /* floating point */ > +} __packed; Haven't looked deeply into the protocol, but still makes me think that the above (since it's the only __packed data type required) might be simply depicted wrongly w.r.t. endianess / data types in use. It might be that the data types have something combined and / or different types. Do I understand correctly that the protocol was basically reverse-engineered? ... > + /* > + * The coordinate system used by the device is different from the > + * coordinate system of the framebuffer in that the x and y axes are > + * swapped, and that the y axis is inverted; so what the device reports > + * as the height is actually the width of the framebuffer and vice > + * versa Missing period. > + */ ... Otherwise it's nice tiny driver. -- With Best Regards, Andy Shevchenko