From: Wolfram Sang <wsa@the-dreams.de>
To: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: linux-i2c@vger.kernel.org, SH-Linux <linux-sh@vger.kernel.org>
Subject: Re: rcar-i2c: always reads a byte
Date: Tue, 11 Mar 2014 17:40:43 +0100 [thread overview]
Message-ID: <20140311164043.GA1179@katana> (raw)
In-Reply-To: <531F3686.7050808@codethink.co.uk>
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On Tue, Mar 11, 2014 at 04:15:02PM +0000, Ben Dooks wrote:
> I have noticed the following behaviour with the i2c-rcar driver
> with the following single i2c_msg structure:
>
> msg[0].addr = 0x12;
> msg[0].flags = I2C_M_RD;
> msg[0].len = 0;
> msg[0].buf = data;
>
> The system issues an address transaction followed by a single byte
> read.
This fits to my observation that the rcar driver cannot do SMBUS_QUICK
(e.g. via i2cdetect). I assumed that handling a length of 0 is broken. I
haven't had a deeper look yet, so I can't say much. So, you either go
for it yourself, or you wait until I posted my IIC enablement series for
Lager. Then, you can switch to the IIC core with the sh_mobile driver.
That one does SMBUS_QUICK correctly.
Regards,
Wolfram
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WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Ben Dooks <ben.dooks@codethink.co.uk>
Cc: linux-i2c@vger.kernel.org, SH-Linux <linux-sh@vger.kernel.org>
Subject: Re: rcar-i2c: always reads a byte
Date: Tue, 11 Mar 2014 16:40:43 +0000 [thread overview]
Message-ID: <20140311164043.GA1179@katana> (raw)
In-Reply-To: <531F3686.7050808@codethink.co.uk>
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On Tue, Mar 11, 2014 at 04:15:02PM +0000, Ben Dooks wrote:
> I have noticed the following behaviour with the i2c-rcar driver
> with the following single i2c_msg structure:
>
> msg[0].addr = 0x12;
> msg[0].flags = I2C_M_RD;
> msg[0].len = 0;
> msg[0].buf = data;
>
> The system issues an address transaction followed by a single byte
> read.
This fits to my observation that the rcar driver cannot do SMBUS_QUICK
(e.g. via i2cdetect). I assumed that handling a length of 0 is broken. I
haven't had a deeper look yet, so I can't say much. So, you either go
for it yourself, or you wait until I posted my IIC enablement series for
Lager. Then, you can switch to the IIC core with the sh_mobile driver.
That one does SMBUS_QUICK correctly.
Regards,
Wolfram
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next prev parent reply other threads:[~2014-03-11 16:40 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-11 16:15 rcar-i2c: always reads a byte Ben Dooks
2014-03-11 16:40 ` Wolfram Sang [this message]
2014-03-11 16:40 ` Wolfram Sang
2014-03-11 16:41 ` Ben Dooks
2014-03-11 16:47 ` Wolfram Sang
2014-03-11 16:47 ` Wolfram Sang
2014-03-11 17:10 ` Ben Dooks
2014-05-05 15:51 ` Wolfram Sang
2014-05-05 15:51 ` Wolfram Sang
2014-03-11 17:24 ` Wolfram Sang
2014-03-11 17:24 ` Wolfram Sang
2014-03-11 17:31 ` Ben Dooks
2014-03-11 17:46 ` Wolfram Sang
2014-03-11 17:46 ` Wolfram Sang
[not found] ` <531F3686.7050808-4yDnlxn2s6sWdaTGBSpHTA@public.gmane.org>
2014-03-12 8:27 ` Michael Lawnick
2014-03-12 8:27 ` Michael Lawnick
2014-03-12 8:39 ` Paul Carpenter
2014-03-12 9:00 ` Michael Lawnick
2014-03-12 9:00 ` Michael Lawnick
[not found] ` <53201A83.7040605-Mmb7MZpHnFY@public.gmane.org>
2014-05-05 13:21 ` Wolfram Sang
2014-05-05 13:21 ` Wolfram Sang
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