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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Jie Deng <jie.deng@intel.com>,
	linux-i2c@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, mst@redhat.com, wsa@kernel.org,
	jasowang@redhat.com, wsa+renesas@sang-engineering.com,
	conghui.chen@intel.com, arnd@arndb.de, kblaiech@mellanox.com,
	jarkko.nikula@linux.intel.com, Sergey.Semin@baikalelectronics.ru,
	rppt@kernel.org, loic.poulain@linaro.org, tali.perry1@gmail.com,
	u.kleine-koenig@pengutronix.de, bjorn.andersson@linaro.org,
	yu1.wang@intel.com, shuo.a.liu@intel.com
Subject: Re: [PATCH v5] i2c: virtio: add a virtio i2c frontend driver
Date: Mon, 1 Mar 2021 14:10:09 +0200	[thread overview]
Message-ID: <YDzZocYCA8UC1FCW@smile.fi.intel.com> (raw)
In-Reply-To: <YDzZdc9+6hEvIDS1@smile.fi.intel.com>

On Mon, Mar 01, 2021 at 02:09:25PM +0200, Andy Shevchenko wrote:
> On Mon, Mar 01, 2021 at 05:24:41PM +0530, Viresh Kumar wrote:
> > On 01-03-21, 14:41, Jie Deng wrote:
> > > +/**
> > > + * struct virtio_i2c_req - the virtio I2C request structure
> > > + * @out_hdr: the OUT header of the virtio I2C message
> > > + * @write_buf: contains one I2C segment being written to the device
> > > + * @read_buf: contains one I2C segment being read from the device
> > > + * @in_hdr: the IN header of the virtio I2C message
> > > + */
> > > +struct virtio_i2c_req {
> > > +	struct virtio_i2c_out_hdr out_hdr;
> > > +	u8 *write_buf;
> > > +	u8 *read_buf;
> > > +	struct virtio_i2c_in_hdr in_hdr;
> > > +};
> > 
> > I am not able to appreciate the use of write/read bufs here as we
> > aren't trying to read/write data in the same transaction. Why do we
> > have two bufs here as well as in specs ?
> 
> I²C and SMBus support bidirectional transfers as well. I think two buffers is
> the right thing to do.

Strictly speaking "half duplex".

-- 
With Best Regards,
Andy Shevchenko



WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Sergey.Semin@baikalelectronics.ru, bjorn.andersson@linaro.org,
	loic.poulain@linaro.org, arnd@arndb.de, mst@redhat.com,
	shuo.a.liu@intel.com, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, wsa@kernel.org,
	wsa+renesas@sang-engineering.com, jarkko.nikula@linux.intel.com,
	linux-i2c@vger.kernel.org, u.kleine-koenig@pengutronix.de,
	kblaiech@mellanox.com, tali.perry1@gmail.com,
	conghui.chen@intel.com, rppt@kernel.org, yu1.wang@intel.com
Subject: Re: [PATCH v5] i2c: virtio: add a virtio i2c frontend driver
Date: Mon, 1 Mar 2021 14:10:09 +0200	[thread overview]
Message-ID: <YDzZocYCA8UC1FCW@smile.fi.intel.com> (raw)
In-Reply-To: <YDzZdc9+6hEvIDS1@smile.fi.intel.com>

On Mon, Mar 01, 2021 at 02:09:25PM +0200, Andy Shevchenko wrote:
> On Mon, Mar 01, 2021 at 05:24:41PM +0530, Viresh Kumar wrote:
> > On 01-03-21, 14:41, Jie Deng wrote:
> > > +/**
> > > + * struct virtio_i2c_req - the virtio I2C request structure
> > > + * @out_hdr: the OUT header of the virtio I2C message
> > > + * @write_buf: contains one I2C segment being written to the device
> > > + * @read_buf: contains one I2C segment being read from the device
> > > + * @in_hdr: the IN header of the virtio I2C message
> > > + */
> > > +struct virtio_i2c_req {
> > > +	struct virtio_i2c_out_hdr out_hdr;
> > > +	u8 *write_buf;
> > > +	u8 *read_buf;
> > > +	struct virtio_i2c_in_hdr in_hdr;
> > > +};
> > 
> > I am not able to appreciate the use of write/read bufs here as we
> > aren't trying to read/write data in the same transaction. Why do we
> > have two bufs here as well as in specs ?
> 
> I²C and SMBus support bidirectional transfers as well. I think two buffers is
> the right thing to do.

Strictly speaking "half duplex".

-- 
With Best Regards,
Andy Shevchenko


_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2021-03-01 12:12 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-01  6:41 [PATCH v5] i2c: virtio: add a virtio i2c frontend driver Jie Deng
2021-03-01  6:41 ` Jie Deng
2021-03-01 11:54 ` Viresh Kumar
2021-03-01 12:09   ` Andy Shevchenko
2021-03-01 12:09     ` Andy Shevchenko
2021-03-01 12:10     ` Andy Shevchenko [this message]
2021-03-01 12:10       ` Andy Shevchenko
2021-03-01 15:46       ` Arnd Bergmann
2021-03-01 15:46         ` Arnd Bergmann
2021-03-02  3:46         ` Viresh Kumar
2021-03-02  3:44       ` Viresh Kumar
2021-03-02  2:21   ` Jie Deng
2021-03-02  2:21     ` Jie Deng
2021-03-02  3:43     ` Viresh Kumar
2021-03-02  6:24       ` Jie Deng
2021-03-02  7:24         ` Viresh Kumar
2021-03-02  8:17           ` Jie Deng
2021-03-02  8:17             ` Jie Deng
2021-03-02  6:28       ` Jie Deng
2021-03-02  6:28         ` Jie Deng
2021-03-01 12:07 ` Andy Shevchenko
2021-03-01 12:07   ` Andy Shevchenko
2021-03-02  7:16   ` Jie Deng
2021-03-02  7:16     ` Jie Deng
2021-03-01 15:19 ` Arnd Bergmann
2021-03-01 15:19   ` Arnd Bergmann
2021-03-02  2:42   ` Jie Deng
2021-03-02  9:51     ` Stefan Hajnoczi
2021-03-02  9:51       ` Stefan Hajnoczi
2021-03-02 10:54       ` Arnd Bergmann
2021-03-02 10:54         ` Arnd Bergmann
2021-03-03 17:48         ` Stefan Hajnoczi
2021-03-03 17:48           ` Stefan Hajnoczi
2021-03-02  4:01   ` Viresh Kumar
2021-03-02  4:22     ` Viresh Kumar
2021-03-02  5:06       ` Jie Deng
2021-03-02  5:06         ` Jie Deng
2021-03-02  5:16         ` Viresh Kumar
2021-03-02  5:42           ` Jason Wang
2021-03-02  5:42             ` Jason Wang
2021-03-02  4:42 ` Viresh Kumar
2021-03-02  5:21   ` Jie Deng
2021-03-02  5:21     ` Jie Deng
2021-03-02  5:25     ` Viresh Kumar
2021-03-03  7:54 ` Viresh Kumar
2021-03-03  8:46   ` Jie Deng
2021-03-03  8:46     ` Jie Deng
2021-03-03  9:38     ` Viresh Kumar
2021-03-04  1:47       ` Jie Deng
2021-03-04  1:47         ` Jie Deng

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