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Date:   Mon, 28 Jun 2021 16:58:15 +0200
From:   Wolfram Sang <wsa@kernel.org>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     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>,
        Jason Wang <jasowang@redhat.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>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        yu1.wang@intel.com, shuo.a.liu@intel.com,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver
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Mail-Followup-To: Wolfram Sang <wsa@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Jie Deng <jie.deng@intel.com>,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Jason Wang <jasowang@redhat.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>,
        Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>,
        Bjorn Andersson <bjorn.andersson@linaro.org>, yu1.wang@intel.com,
        shuo.a.liu@intel.com, Viresh Kumar <viresh.kumar@linaro.org>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>
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> You can fine Viresh's vhost-user implementation at
> https://lore.kernel.org/qemu-devel/cover.1617278395.git.viresh.kumar@linaro.org/t/#m3b5044bad9769b170f505e63bd081eb27cef8db2

It looks OK so far; yet, it is not complete. But it might be bearable
in the end.

> As you say, it does get a bit clumsy, but I think there is also a good argument
> to be made that the clumsiness is based on the host Linux user interface
> more than the on the requirements of the physical interface,
> and that should not have to be reflected in the virtio specification.

Makes sense to me.

> Right, this one has come up before as well: the preliminary result
> was to assume that this probably won't be needed, but would be easy
> enough to add later if necessary.

If adding support incrementally works for such an interface, this makes
sense as well.

So, where are we? As I understand, this v10 does not support I2C
transactions (or I2C_RDWR as you said). But you want to support all
clients. So, this doesn't match, or?


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