From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1FC3C388F7 for ; Thu, 22 Oct 2020 13:31:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B45920BED for ; Thu, 22 Oct 2020 13:31:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2900138AbgJVNbt (ORCPT ); Thu, 22 Oct 2020 09:31:49 -0400 Received: from mx2.suse.de ([195.135.220.15]:47294 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2443345AbgJVNbt (ORCPT ); Thu, 22 Oct 2020 09:31:49 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3D5EAACAA; Thu, 22 Oct 2020 13:31:47 +0000 (UTC) Date: Thu, 22 Oct 2020 15:31:47 +0200 Message-ID: From: Takashi Iwai To: Maxime Ripard Cc: Jaroslav Kysela , Takashi Iwai , Liam Girdwood , Mark Brown , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Dom Cobley , Dave Stevenson , Nicolas Saenz Julienne Subject: Re: Context expectations in ALSA In-Reply-To: <20201022132412.vntap4kfb2aj24qy@gilmour.lan> References: <20201022095041.44jytaelnlako54w@gilmour.lan> <30226f94-72e9-34d2-17d0-11d2501053f0@perex.cz> <20201022125741.xxibhwgcr2mhxehe@gilmour.lan> <20201022132412.vntap4kfb2aj24qy@gilmour.lan> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 22 Oct 2020 15:24:12 +0200, Maxime Ripard wrote: > > Hi Takashi, > > On Thu, Oct 22, 2020 at 03:20:49PM +0200, Takashi Iwai wrote: > > On Thu, 22 Oct 2020 14:57:41 +0200, > > Maxime Ripard wrote: > > > > > > On Thu, Oct 22, 2020 at 12:03:19PM +0200, Jaroslav Kysela wrote: > > > > Dne 22. 10. 20 v 11:50 Maxime Ripard napsal(a): > > > > > > > > > So, I'm not really sure what I'm supposed to do here. The drivers > > > > > involved don't appear to be doing anything extraordinary, but the issues > > > > > lockdep report are definitely valid too. What are the expectations in > > > > > terms of context from ALSA when running the callbacks, and how can we > > > > > fix it? > > > > > > > > I think that you should set the non-atomic flag and wake up the workqueue or > > > > so from interrupt handler in this case. Call snd_pcm_period_elapsed() from the > > > > workqueue not the interrupt handler context. > > > > > > Yeah, that was my first guess too. However, the DMA driver uses some > > > kind of generic helpers using a tasklet, so getting rid of it would take > > > some work and would very likely not be eligible for stable. > > > > Who sets the nonatomic flag for vc4? I couldn't find the relevant > > code in the latest upstream. > > Sorry if this wasn't clear enough, it's not there at the moment, ALSA > takes a spinlock and lockdep complains that we're sleeping in an atomic > context. > > I tried to add the nonatomic flag in my tree to see if it was fixing the > issue, but ran into another lockdep complain now with ALSA taking a > mutex in a tasklet. I see, thanks for clarification. > > Ideally dmaengine PCM helper should support the nonatomic mode, but > > until then, the other side needs to drop the nonatomic flag, I > > suppose. > > In this case, I'm not sure the blame is in the PCM helper but if there's > any blame, I guess it's the virt-chan layer inside dmaengine (so for > providers) that use a tasklet instead of something that allows sleeping Well, we have to align either to atomic or non-atomic operation. If we want to solve solely in vc4, the fix would be to make the trigger action into some own work. Takashi