From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hein_Tibosch Subject: Re: [PATCH v3] mmc: Make ID freq configurable Date: Sun, 03 Jan 2010 16:00:09 +0800 Message-ID: <4B404E89.4060103@yahoo.es> References: <1246492196.2980.17.camel@linux-51e8.site> <20090702135849.21370282@hskinnemoen-d830> <1246537056.2980.60.camel@linux-51e8.site> <4B3E570C.2060602@yahoo.es> <63809451-ED1D-487A-AE63-F72B23D136D8@niasdigital.com> <4B3F019F.6010306@yahoo.es> <49985427-DCB9-40E1-815B-43C812B41DE3@niasdigital.com> <20100102130809.121b7e10@mjolnir.ossman.eu> <20100103003804.66021fe9@mjolnir.ossman.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp-vbr4.xs4all.nl ([194.109.24.24]:1945 "EHLO smtp-vbr4.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751583Ab0ACIB2 (ORCPT ); Sun, 3 Jan 2010 03:01:28 -0500 In-Reply-To: <20100103003804.66021fe9@mjolnir.ossman.eu> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Pierre Ossman Cc: Ben Nizette , Sascha Hauer , Adrian Hunter , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Matt Fleming Pierre Ossman wrote: > On Sun, 3 Jan 2010 09:23:30 +1100 > Ben Nizette wrote: > > >>> Broken cards seem to be all over the spectrum, so I wouldn't be >>> suprised if you find ones that break if you go too low as well. >>> >> Yea good point, though given there might not even be a One Freq to Rule Them All, how about: >> >> ---8<--- >> >> From: Ben Nizette >> Subject: [PATCH v3] mmc: Make ID freq configurable >> >> While the SD spec specifies a range of frequencies for the ID phase from 100-400kHz, not all cards play by the rules. This patch adds a Kconfig option to allow the user to tweak this to their card/host config, though the default of 250kHz should be fine for all spec-abiding cards and most others besides. >> >> Signed-off-by: Ben Nizette >> >> > > This is not a good solution. We all use the same pool of cards so we > should all be using the same init sequence. If there isn't a single > frequency where all cards will work, then we'll have to make something > more advanced where the kernel will try the init several times with > different clocking. > As I'm lucky to have main-stream cards that break the rule (on avr32/AP7) I'll dive deeper into it and see if I can make it "automatic" so that initialization will work for any of cards. Indeed using a kind of 'bisect approach' approach. ... although I must say that before Sascha Hauer's patch, we never had problems with any of the cards, using the controller's minimum freq of 137 Khz. Hein