From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Jarzmik Subject: Re: [PATCH] ALSA: pxa2xx: fix ac97 cold reset for pxa27x Date: Fri, 28 Dec 2012 19:22:17 +0100 Message-ID: <87wqw2rq92.fsf@free.fr> References: <1356707815-3235-1-git-send-email-mikedunn@newsguy.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from smtp1-g21.free.fr (smtp1-g21.free.fr [212.27.42.1]) by alsa0.perex.cz (Postfix) with ESMTP id B8D5F2602AE for ; Fri, 28 Dec 2012 19:22:29 +0100 (CET) In-Reply-To: <1356707815-3235-1-git-send-email-mikedunn@newsguy.com> (Mike Dunn's message of "Fri, 28 Dec 2012 07:16:55 -0800") 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: Mike Dunn Cc: Marek Vasut , alsa-devel@alsa-project.org, Mark Brown , Eric Miao List-Id: alsa-devel@alsa-project.org 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 :) If you've tested that and if it work, that's great news. I'll test it also to crosscheck. 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. Cheers. -- Robert