Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751514Ab2KLJn6 (ORCPT ); Mon, 12 Nov 2012 04:43:58 -0500 Received: from mail-wi0-f178.google.com ([209.85.212.178]:35023 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750858Ab2KLJn4 (ORCPT ); Mon, 12 Nov 2012 04:43:56 -0500 MIME-Version: 1.0 X-Originating-IP: [178.83.130.250] In-Reply-To: <20121112072410.GA925@avionic-0098.mockup.avionic-design.de> References: <1352469579-3337-1-git-send-email-thierry.reding@avionic-design.de> <1352469579-3337-3-git-send-email-thierry.reding@avionic-design.de> <509D28B6.3060207@vodafone.de> <20121110210118.GA26809@avionic-0098.mockup.avionic-design.de> <20121111144644.GK5854@phenom.ffwll.local> <20121112072410.GA925@avionic-0098.mockup.avionic-design.de> Date: Mon, 12 Nov 2012 10:43:54 +0100 X-Google-Sender-Auth: QI2nVwEfM24b8_GPhRfYGACMjD4 Message-ID: Subject: Re: [PATCH 2/2] drm: tegra: Add HDMI support From: Daniel Vetter To: Thierry Reding Cc: =?ISO-8859-1?Q?Christian_K=F6nig?= , devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, Dave Airlie Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1552 Lines: 31 On Mon, Nov 12, 2012 at 8:24 AM, Thierry Reding wrote: > Actually what I had in mind was a packed binary representation of > infoframes as specified by HDMI 1.3a (I don't have access to 1.4, but I > would think it doesn't differ in this respect) in section 5.3 and 5.3.5 > more specifically. According to the specification, the ECC bytes only > come into play at a later stage, when data is actually transmitted on > the TMDS link (Section 5.2.3). Tegra, nouveau and radeon also seem to be > doing the checksumming in hardware, so I guess we don't need to compute > the ECC bytes in software at all (for now). > > Once we have this for the AVI infoframes I guess the same concept can be > used for audio infoframes and for vendor-specific infoframes (for HDMI > 1.4 3D). Iirc there's more than one checksum: The ECC field at byte 3 and the checksum field at byte 4. All intel hw computes the ECC itself, but some want us to store the infoframe with an empty ECC byte as placeholder, whereas others (sdvo encoders) insert that byte themselves, i.e. the infoframe is actually one byte shorter. In any case, that kind of mangling can be done in the driver with easy. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/