Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <c193b92d8d22ba439bb1b260d26d4b76f57d4840.1615889867.git.jie.deng@intel.com>
 <20210316074409.2afwsaeqxuwvj7bd@vireshk-i7> <0dfff1ac-50bb-b5bc-72ea-880fd52ed60d@metux.net>
In-Reply-To: <0dfff1ac-50bb-b5bc-72ea-880fd52ed60d@metux.net>
From:   Arnd Bergmann <arnd@arndb.de>
Date:   Thu, 18 Mar 2021 15:52:41 +0100
Message-ID: <CAK8P3a3f9bKdOOMgrA9TfeObyEd+eeg8JcTVT8AyS1+s=X2AjQ@mail.gmail.com>
Subject: Re: [PATCH v8] i2c: virtio: add a virtio i2c frontend driver
To:     "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Cc:     Viresh Kumar <viresh.kumar@linaro.org>,
        Jie Deng <jie.deng@intel.com>,
        Linux I2C <linux-i2c@vger.kernel.org>,
        virtualization@lists.linux-foundation.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Wolfram Sang <wsa@kernel.org>,
        Jason Wang <jasowang@redhat.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        conghui.chen@intel.com, kblaiech@mellanox.com,
        jarkko.nikula@linux.intel.com,
        Sergey Semin <Sergey.Semin@baikalelectronics.ru>,
        Mike Rapoport <rppt@kernel.org>, loic.poulain@linaro.org,
        Tali Perry <tali.perry1@gmail.com>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        yu1.wang@intel.com, shuo.a.liu@intel.com,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Mar 18, 2021 at 3:42 PM Enrico Weigelt, metux IT consult
<lkml@metux.net> wrote:
>
> On 16.03.21 08:44, Viresh Kumar wrote:
>
> > FWIW, this limits this driver to support a single device ever. We
> > can't bind multiple devices to this driver now. Yeah, perhaps we will
> > never be required to do so, but who knows.
>
> Actually, I believe multiple devices really should be possible.
>
> The major benefit of virtio-i2c is either bridging certan real bus'es
> into a confined workload, or creating virtual hw testbeds w/o having to
> write a complete emulation (in this case, for dozens of different i2c
> controllers) - and having multiple i2c interfaces in one machine isn't
> exactly rare.

Allowing multiple virtio-i2c controllers in one system, and multiple i2c
devices attached to each controller is clearly something that has to work.

I don't actually see a limitation though. Viresh, what is the problem
you see for having multiple controllers?

         Arnd