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,DKIM_SIGNED, DKIM_VALID,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 A5D1DC433B4 for ; Fri, 9 Apr 2021 07:40:35 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 386B961179 for ; Fri, 9 Apr 2021 07:40:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 386B961179 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id D3BAA41; Fri, 9 Apr 2021 09:39:41 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz D3BAA41 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1617954031; bh=4z+00jRt9OT6XdaLkDcbF4fxQSEQQWv09jk0QzyvIEs=; h=Date:From:To:Subject:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=Lcuyee/v2wYaJ42JkUv0DCiAaN3GELEEWK2rK9lrlc5C2hv1sIAbjVH9OqTzbaET7 bszxc7qjh26S8ZmPgCLpDbOGg2owy2vrhFJ8TBQaiVh7daZFSq7nf6Y6H74mBbI/sQ UIydqAuBuGNlOzipWQS2iQiuVlcm4TtaUD2+TeJE= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 44FB1F80168; Fri, 9 Apr 2021 09:39:41 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 44EBFF8016A; Fri, 9 Apr 2021 09:39:37 +0200 (CEST) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id C193FF80113 for ; Fri, 9 Apr 2021 09:39:31 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz C193FF80113 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 178C8AFE8; Fri, 9 Apr 2021 07:39:30 +0000 (UTC) Date: Fri, 09 Apr 2021 09:39:29 +0200 Message-ID: From: Takashi Iwai To: Pierre-Louis Bossart Subject: Re: [PATCH] ALSA: core - add more card sysfs entries In-Reply-To: References: <20210408094314.1322802-1-perex@perex.cz> <20210408103819.GA40407@workstation> <45acc908-3603-3479-9fb2-5206339a9ace@perex.cz> <20210408120502.GA4516@sirena.org.uk> <56c874ae-e801-63df-19fa-a1325f6104ca@perex.cz> <3107db1d-f97d-539a-05db-6f880b762f00@linux.intel.com> <3b33595e-777c-90b2-6d65-346c9bf6e003@perex.cz> 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 Cc: ALSA development , Mark Brown X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Thu, 08 Apr 2021 20:51:41 +0200, Pierre-Louis Bossart wrote: > > > > >>> When we have a common standard layer for the plug-and-play handling (udev), we > >>> should concentrate to allow changing / refining of this information there. > >>> Those strings are not used for anything else than the user space. So from my > >>> view, there's no reason to create another mechanism to handle the overrides. > >>> It should be a safe, fast, flexible and_optional_ solution. The udev can > >>> alter the sysfs attributes directly without any hassle with the file > >>> modifications or looking for another way to pass / store this information > >>> somewhere. > >> > >> There's one part where I am lost. > >> > >> The initial idea of udev what to modify kernel parameters to pick a > >> different path for firmware/topology before probing the PCI driver. At > > > > This may be a problematic point. The kernel cmdline cannot be modified from > > udev (as far as I know). The module parameters can be set using modprobe's > > config files or when loaded with sysfs attributes (/sys/module/*/parameters). > > Eventually, you can call the modprobe command with custom module parameters > > when the appropriate MODALIAS is probed. > > > > Perhaps, I'm missing something here, too. Some example udev rules may help. > > see the example shared by Curtis > > SUBSYSTEM=="pci", ATTR{vendor}=="0x8086", ATTR{device}=="0xa0c8", > ATTR{class}=="0x040100", ATTRS{[dmi/id]board_name}=="Eldrid", > RUN+="/sbin/modprobe snd_sof_pci tplg_path=intel/sof-tplg/pdm1" > > Those 'path' parameters would have to be set prior to creating the > card, making them writable via sysfs would not work, the firmware and > topology are already loaded and changing the paths would have no > effect. Couldn't the driver probe the firmware files with some device-specific string suffix at first? e.g. the driver can issue request_firmware() with $base_file-$dmi_board at first, then falls back to the generic $base_file. A similar method was already used in Broadcom WiFi driver. Also, the driver may do request_firmware() with a fixed path for the custom firmware at first (e.g. "intel/sof-tplg-custom"); then a system integrator may set up a specific configuration even that doesn't match with DMI or whatever identifier. Takashi