Re: [PATCH] HID: logitech-dj: add support for the static device in the Powerplay mat/receiver

From: Jiri Kosina <jikos@kernel.org>
To: "Filipe Laíns" <lains@archlinux.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	Nestor Lopez Casado <nlopezcasad@logitech.com>
Subject: Re: [PATCH] HID: logitech-dj: add support for the static device in the Powerplay mat/receiver
Date: Tue, 10 Mar 2020 14:22:16 +0100 (CET)	[thread overview]
Message-ID: <nycvar.YFH.7.76.2003101301280.19500@cbobk.fhfr.pm> (raw)
In-Reply-To: <5a93677bd6238a9d7928e4fd16a8915faeb5f19e.camel@archlinux.org>

On Wed, 12 Feb 2020, Filipe Laíns wrote:

> > > +	/* custom receiver device (eg. powerplay) */
> > > +	if (hidpp_report->device_index == 7) {
> > > +		workitem.reports_supported |= HIDPP;
> > > +	}
> > > +
> > 
> > I guess we can't do anything else than to trust Logitech that they will 
> > not assign conflicting device_index ID in the future to something that 
> > will not be HID++, right?
> > 
> > Or is this properly documented somewhere?
> > 
> > Thanks,
> 
> 
> CCing Nestor
> 
> Yes, we need to trust Logitech on this. There's isn't anything
> documented regarding this AFAIK.
> 
> Even if Logitech released a device with index 7 that didn't support
> HID++, it wouldn't be that big of an issue. We would just end up with a
> hidraw node which would export a vendor page report descriptor but the
> device wouldn't actually reply to anything.

Given the silence from Nestor, I guess we can just apply this for 5.7; 
pushing to for-5.7/logitech branch.

Thanks,

-- 
Jiri Kosina
SUSE Labs