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Date: Sat, 15 Jun 2024 15:12:55 +0200
From: Lukas Wunner <lukas@wunner.de>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alistair Francis <alistair23@gmail.com>, bhelgaas@google.com,
	linux-pci@vger.kernel.org, alex.williamson@redhat.com,
	christian.koenig@amd.com, kch@nvidia.com,
	gregkh@linuxfoundation.org, logang@deltatee.com,
	linux-kernel@vger.kernel.org, chaitanyak@nvidia.com,
	rdunlap@infradead.org, Alistair Francis <alistair.francis@wdc.com>
Subject: Re: [PATCH v10 3/4] PCI/DOE: Expose the DOE features via sysfs
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References: <20240522101142.559733-1-alistair.francis@wdc.com>
 <20240522101142.559733-3-alistair.francis@wdc.com>
 <20240523122448.0000799f@Huawei.com>
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On Thu, May 23, 2024 at 12:24:48PM +0100, Jonathan Cameron wrote:
> What happens if multiple DOE which support the same protocol?
> (IIRC that's allowed).  You probably need to paper over repeat
> sysfs attributes and make sure they don't get double freed etc.

So I believe this was fixed in v11 but assuming the point here is
to allow lspci to display supported protocols without speaking DOE
with the device, the way it's implemented now user space cannot
discern which mailbox supports which protocol.  Or if multiple
mailboxes support the same protocol.  I'm wondering in how far
that limits the usefulness of the feature.

sysfs doesn't support nested groups.  But we could dynamically
create one attribute group per mailbox.  Or have one file per
mailbox in a common doe_features group, each file containing
all the supported protocols. Hm...

Thanks,

Lukas