From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752699Ab1K1Hzf (ORCPT ); Mon, 28 Nov 2011 02:55:35 -0500 Received: from smtp-out-213.synserver.de ([212.40.185.213]:1087 "HELO smtp-out-211.synserver.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1751161Ab1K1Hze (ORCPT ); Mon, 28 Nov 2011 02:55:34 -0500 X-SynServer-TrustedSrc: 1 X-SynServer-AuthUser: lars@metafoo.de X-SynServer-PPID: 25128 Message-ID: <4ED33EB1.6030200@metafoo.de> Date: Mon, 28 Nov 2011 08:56:33 +0100 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.24) Gecko/20111114 Iceowl/1.0b2 Icedove/3.1.16 MIME-Version: 1.0 To: Mike Frysinger CC: Mark Brown , Liam Girdwood , Andrew Morton , linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org, drivers@analog.com, stable@kernel.org Subject: Re: [PATCH 2/8] firmware: Sigma: Skip header during CRC generation References: <1322138908-32127-1-git-send-email-lars@metafoo.de> <201111241222.00189.vapier@gentoo.org> <4ECF580E.3060301@metafoo.de> <201111251500.52711.vapier@gentoo.org> In-Reply-To: <201111251500.52711.vapier@gentoo.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/25/2011 09:00 PM, Mike Frysinger wrote: > On Friday 25 November 2011 03:55:42 Lars-Peter Clausen wrote: >> On 11/24/2011 06:21 PM, Mike Frysinger wrote: >>> On Thursday 24 November 2011 07:48:21 Lars-Peter Clausen wrote: >>>> The firmware header is not part of the CRC, so skip it. Otherwise the >>>> firmware will be rejected due to non-matching CRCs. >>> >>> that's because you didn't compare to the right value ;). include the CRC >>> -> compare to 0. omit the CRC -> compare to the CRC value. >> >> Does this really work if the CRC is inserted somewhere in the middle of the >> bytestream? > > i don't think the position matters to the CRC algorithm used by sigmadsp. > math principle: a ^ b ^ c is the same thing as b ^ a ^ c and c ^ b ^ a. If CRC algorithms were commutative they would be pretty weak, I guess ;) > > i could be wrong as to the CRC algo used though. simple enough for you to > check -- i implemented this firmware code based on a spec i wrote up for the > sigmadsp peeps; i never actually had real firmware to test with. > -mike It does not work. - Lars