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Date:   Fri, 11 Jun 2021 16:56:52 +0530
From:   Vinod Koul <vkoul@kernel.org>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
        alsa-devel@alsa-project.org, Leon Romanovsky <leon@kernel.org>,
        gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
        Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
        hui.wang@canonical.com, Dave Ertman <david.m.ertman@intel.com>,
        sanyog.r.kale@intel.com,
        Bard Liao <yung-chuan.liao@linux.intel.com>,
        rander.wang@linux.intel.com, bard.liao@intel.com
Subject: Re: [PATCH v4] soundwire: intel: move to auxiliary bus
Message-ID: <YMNIfHPRcgKLXJ0v@vkoul-mobl>
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On 09-06-21, 12:10, Jason Gunthorpe wrote:
> On Wed, Jun 09, 2021 at 09:44:08AM -0500, Pierre-Louis Bossart wrote:
> 
> > The consensus for the auxiliary_device model was hard to reach, and the
> > agreement was to align on a minimal model. If you disagree with the
> > directions, you will have to convince Nvidia/Mellanox and Intel networking
> > folks who contributed the solution to do something different.
> 
> The purpose of the aux devices was primarily to bind a *software*
> interface between two parts of the kernel.

Then I dont think this example is valid... This example has a PCI device,
which represents a DSP, HDA controller, DMICs, Soundwire
links... So at least here it is hardware.

> If there is a strong defined HW boundary and no software interface
> then the mfd subsytem may be a better choice.

More I think that might be better choice for this example, but then MFD
is a 'platform device' and Greg already nacked that

> For a software layer I expect to see some 'handle' and then a set of
> APIs to work within that. It is OK if that 'handle' refers to some HW
> resources that the API needs to work, the purpose of this is to
> control HW after all.
> 
> You might help Vinod by explaining what the SW API is here.
> 
> Jason

-- 
~Vinod