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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 8A960C433B4 for ; Fri, 21 May 2021 14:26:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 626C3613E2 for ; Fri, 21 May 2021 14:26:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236743AbhEUO12 (ORCPT ); Fri, 21 May 2021 10:27:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:36952 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235185AbhEUO1Y (ORCPT ); Fri, 21 May 2021 10:27:24 -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 BA476AAA6; Fri, 21 May 2021 14:26:00 +0000 (UTC) Date: Fri, 21 May 2021 16:26:00 +0200 Message-ID: From: Takashi Iwai To: Cc: , , , , , , , , , , , Subject: Re: [RFC PATCH 0/6] soc-pcm: Add separate snd_pcm_runtime for BEs In-Reply-To: <2c2661d3-78a8-de55-e976-b87f3658a093@microchip.com> References: <20210519104842.977895-1-codrin.ciubotariu@microchip.com> <056e560e-d06d-23bc-b041-60890fa51e63@microchip.com> <2c2661d3-78a8-de55-e976-b87f3658a093@microchip.com> 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, 20 May 2021 15:59:02 +0200, wrote: > > On 19.05.2021 18:41, Takashi Iwai wrote: > > On Wed, 19 May 2021 17:08:10 +0200, > > wrote: > >> > >> On 19.05.2021 17:15, Takashi Iwai wrote: > >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > >>> > >>> On Wed, 19 May 2021 12:48:36 +0200, > >>> Codrin Ciubotariu wrote: > >>>> > >>>> This patchset adds a different snd_pcm_runtime in the BE's substream, > >>>> replacing the FE's snd_pcm_runtime. With a different structure, the BE > >>>> HW capabilities and constraints will no longer merge with the FE ones. > >>>> This allows for error detection if the be_hw_params_fixup() applies HW > >>>> parameters not supported by the BE DAIs. Also, it calculates values > >>>> needed for mem-to-dev/dev-to-mem DMA transfers, such as buffer size and > >>>> period size, if needed. > >>>> > >>>> The first 4 patches are preparatory patches, that just group and export > >>>> functions used to allocate and initialize the snd_pcm_runtime. Also, the > >>>> functions that set and apply the HW constraints are exported. > >>>> The 5th patch does (almost) everything need to create the new snd_pcm_runtime > >>>> for BEs, which includes allocation, initializing the HW capabilities, > >>>> HW constraints and HW parameters. The BE HW parameters are no longer > >>>> copied from the FE. They are recalculated, based on HW capabilities, > >>>> constraints and the be_hw_params_fixup() callback. > >>>> The 6th and last patch basically adds support for the PCM generic > >>>> dmaengine to be used as a platform driver for BE DAI links. It allocates > >>>> a buffer, needed by the DMA transfers that do not support dev-to-dev > >>>> transfers between FE and BE DAIs. > >>>> > >>>> This is a superset of > >>>> https://mailman.alsa-project.org/pipermail/alsa-devel/2021-March/182630.html > >>>> which only handles the BE HW constraints. This patchset aims to be more > >>>> complete, defining a a snd_pcm_runtime between each FE and BE and can > >>>> be used between any DAI link connection. I am sure I am not handling all > >>>> the needed members of snd_pcm_runtime (such as handling > >>>> struct snd_pcm_mmap_status *status), but I would like to have your > >>>> feedback regarding this idea. > >>> > >>> I'm also concerned about the handling of other fields in runtime > >>> object, maybe allocating a complete runtime object for each BE is an > >>> overkill and fragile. Could it be rather only hw_constraints to be > >>> unique for each BE, instead? > >> > >> I tried with only the hw constraints in the previous patchset and it's > >> difficult to handle the snd_pcm_hw_rule_add() calls, without changing > >> the function's declaration. This solution requires no changes to > >> constraints API, nor to their 'clients'. I agree that handling all the > >> runtime fields might be over-complicated. From what I see, the scary > >> ones are used to describe the buffer and the status of the transfers. I > >> do not think there are BEs that use these values at this moment (the FE > >> ones). I think that the HW params, private section, hardware description > >> and maybe DMA members (at least in my case) are mostly needed by BEs. > > > > OK, I'll check your previous series again, but my gut feeling is for > > pursuit to the hw_constraints hacks. e.g. we may split > > snd_pcm_hw_constraints and snd_pcm_hw_rule, too, if that matters. > > Something like adding snd_pcm_hw_rule directly under > snd_pcm_runtime, to store the BE constraints? It could work, but I think > we should also be able to remove rules, if one BE gets disconnected. > This means that we will need a way to identify or separate them, for > each BE, right? Well, if each BE needs a different set of hw constraint rules, it needs its own unique copies instead of sharing the rules. Is it your requirement? Takashi