linux-kernel - Re: [PATCH] soundwire: fix initializing sysfs for same devices on different buses

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Message-ID: <c7fb4ead-13af-438b-a199-c52105545047@linux.intel.com>
Date:   Thu, 5 Oct 2023 08:24:39 -0400
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Vinod Koul <vkoul@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Takashi Iwai <tiwai@...e.de>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Vijendar Mukunda <Vijendar.Mukunda@....com>,
        Mastan Katragadda <Mastan.Katragadda@....com>
Subject: Re: [PATCH] soundwire: fix initializing sysfs for same devices on
 different buses




> I think we keep circling on the differences between "Controller" and
> "link" (aka bus). A Controller can have one or more links. A system can
> have one or more controllers.
> 
> Intel platforms have one controller and 4 or more links.
> QCOM platforms have one or more controllers with one link each.
> 
> I am not sure how this IDA-generated bus_id helps deal with these two
> cases, since we can't really make any assumptions on how
> controllers/links will be started and probed.
> 
> What we are missing is a hierarchical controller/link definition, IOW a
> controller_id should be given to the master by a higher level instead of
> using an IDA.

Tentative patches to introduce a 'controller_id' that's not an IDA are
here: https://github.com/thesofproject/linux/pull/4616

Initial results are positive for Intel devices. it *should* work for
other devices but I can't test. If folks at Linaro/Qualcomm and AMD can
give it a try, that would be much appreciated.

Thanks.