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References: <20221205210354.11846-1-andrew.smirnov@gmail.com>
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From:   David Rheinsberg <david.rheinsberg@gmail.com>
Date:   Thu, 8 Dec 2022 16:46:04 +0100
Message-ID: <CADyDSO4uh6b+sSZTkZ2_DR923=bA=kXgK1LqUMkknCMzf_DSwQ@mail.gmail.com>
Subject: Re: [RFC PATCH 0/2] Handling of non-numbered feature reports by hidraw
To:     Andrey Smirnov <andrew.smirnov@gmail.com>
Cc:     linux-input@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
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Hi

On Mon, 5 Dec 2022 at 22:04, Andrey Smirnov <andrew.smirnov@gmail.com> wrote:
> I'm working on a firmware of a device that exposes a HID interface via
> USB and/or BLE and uses, among other things, non-numbered feature
> reports. Included in this series are two paches I had to create in
> order for hidraw devices created for aforementioned subsystems to
> behave in the same way when exerciesd by the same test tool.
>
> I don't know if the patches are acceptable as-is WRT to not breaking
> existing userspace, hence the RFC tag.

Can you elaborate why you remove the special handling from USBHID but
add it to UHID? They both operate logically on the same level, so
shouldn't we simply adjust uhid to include the report-id in buf[0]?

Also, you override buf[0] in UHID, so I wonder what UHID currently
returns there?

IOW, can you elaborate a bit what the current behavior of each of the
involved modules is, and what behavior you would expect? This would
allow to better understand what you are trying to achieve. The more
context you can give, the easier it is to understand what happens
there.

Thanks!
David