From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Dunn Subject: Re: [PATCH] ALSA: pxa2xx: fix ac97 cold reset for pxa27x Date: Fri, 28 Dec 2012 18:26:26 -0800 Message-ID: <50DE54D2.9040608@newsguy.com> References: <1356707815-3235-1-git-send-email-mikedunn@newsguy.com> <87wqw2rq92.fsf@free.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.newsguy.com (smtp.newsguy.com [74.209.136.69]) by alsa0.perex.cz (Postfix) with ESMTP id 6F0C32615D7 for ; Sat, 29 Dec 2012 03:26:02 +0100 (CET) In-Reply-To: <87wqw2rq92.fsf@free.fr> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Robert Jarzmik Cc: Marek Vasut , alsa-devel@alsa-project.org, Mark Brown , Eric Miao List-Id: alsa-devel@alsa-project.org On 12/28/2012 10:22 AM, Robert Jarzmik wrote: > Mike Dunn writes: > >> Currently, ac97 reset is broken on PXA27x. Through trial-and-error (the pxa270 >> developer's manual is mostly incoherent on the topic of ac97 reset), I fixed it >> by setting the WARM_RST bit in the GCR register at the end of the cold reset, >> and then skipping the warm reset if the link is already up and running. >> >> It appears that setting the WARM_RST bit is a necessary final step during cold >> reset. I think that the PXA25x and PXA3xx may currently be working correctly >> because WARM_RST is set within the warm reset routine, and the codec drivers >> always follow a cold reset with a warm reset during their initialization. so >> this combination effectively completes a cold reset. This doesn't work on the >> PXA27x because its warm reset routine contains additional code for working >> around a hardware bug in the warm reset sequence, which causes the reset >> sequence to fail. I only have a PXA27x platform for testing, so this patch only >> affects the PXA27x. > > Hi Mike, > > I'm glad you take over that burden too :) No one else wants to work on this ancient hardware. It's all Kirkwood this and Omap that :) Want to get the kernel fully functional on this old but still widely available device. > If you've tested that and if it work, that's great news. I'll test it also to > crosscheck. Thanks. I'd really appreciate that. Yes, it works for me. > > This topic was discussed several years ago here : > http://www.spinics.net/lists/alsa-devel/msg12327.html > > I think Mark has a much better view on the silicon defect, he will be of much > more help than me. Thanks for the pointer. I should have done some searches on this myself. I would have if I was hitting a wall, but I chanced upon the solution pretty quickly. Mike