Date: Tue, 1 Aug 2017 23:47:38 +0200
From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: "Andrew F. Davis" <afd@ti.com>, Arnd Bergmann <arnd@arndb.de>,
        linux-i2c@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        linux-doc@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Przemyslaw Sroka <psroka@cadence.com>,
        Arkadiusz Golec <agolec@cadence.com>,
        Alan Douglas <adouglas@cadence.com>,
        Bartosz Folta <bfolta@cadence.com>, Damian Kos <dkos@cadence.com>,
        Alicja Jurasik-Urbaniak <alicja@cadence.com>,
        Jan Kotas <jank@cadence.com>, Cyprian Wronka <cwronka@cadence.com>,
        Alexandre Belloni <alexandre.belloni@free-electrons.com>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
        Pawel Moll <pawel.moll@arm.com>, Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>, devicetree@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 2/5] i3c: Add core I3C infrastructure
Message-ID: <20170801234738.148a874c@bbrezillon>
In-Reply-To: <20170801172703.GA2737@katana>
References: <1501518290-5723-1-git-send-email-boris.brezillon@free-electrons.com>
        <1501518290-5723-3-git-send-email-boris.brezillon@free-electrons.com>
        <CAK8P3a06GoMdKdn=3Cq0FUwYnjGX0oG+FQLjxfiasVDpbonWRw@mail.gmail.com>
        <20170731231509.77d1fba4@bbrezillon>
        <20170731214211.GA11776@tetsubishi>
        <1538596b-80ed-7800-db97-70e73b90b9e2@ti.com>
        <20170801172703.GA2737@katana>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 841
Lines: 24

Le Tue, 1 Aug 2017 19:27:03 +0200,
Wolfram Sang <wsa@the-dreams.de> a écrit :

> > I'm surprised they didn't allow for slave clock stretching when
> > communicating with a legacy i2c device, it will prohibit use of a rather
> > large class of devices. :(  
> 
> Yes, but I3C is push/pull IIRC.

It is.

> 
> > As for interrupts you are always free to wire up an out-of-band
> > interrupt like before. :)  
> 
> Yes, my wording was a bit too strong. It is possible, sure. Yet, I
> understood that one of the features of I3C is to have in-band interrupt
> support. We will see if the demand for backward compatibility or "saving
> pins" is higher.
> 

Indeed, you can use in-band interrupts if your device is able to
generate them, but that doesn't prevent I3C device designers from using
an external pin to signal interrupts if they prefer.