From: Wolfram Sang <wsa@the-dreams.de>
To: Bryan Evenson <bevenson@melinkcorp.com>
Cc: "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
Ludovic Desroches <ludovic.desroches@atmel.com>
Subject: Re: Error using at91-i2c driver in kernel 4.4.x
Date: Thu, 25 May 2017 01:07:08 +0200 [thread overview]
Message-ID: <20170524230708.GA1456@katana> (raw)
In-Reply-To: <DM5PR05MB29541B7EC525C8438538352ABBFE0@DM5PR05MB2954.namprd05.prod.outlook.com>
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> As usual, five minutes after I ask a question I get further. I tried
> changing the ioctl to I2C_SLAVE_FORCE, and now I can talk to my
> EEPROM. I'm happy it's now working, but I'm concerned about why I now
> need to force the slave address. Is this because I now need to set
> things up differently, or is it a problem with the driver?
From userspace, you cannot access an I2C client which has a kernel
driver bound to it unless you use I2C_SLAVE_FORCE. And you really should
not do that because you could confuse the kernel driver.
Your old kernel probably did not bind a driver to the EEPROM, so you
could access it from userspace.
Since your DT now describes the EEPROM, why don't you simply access the
'eeprom' file in sysfs?
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next prev parent reply other threads:[~2017-05-24 23:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 18:18 Error using at91-i2c driver in kernel 4.4.x Bryan Evenson
2017-05-24 18:35 ` Bryan Evenson
2017-05-24 23:07 ` Wolfram Sang [this message]
2017-05-25 14:23 ` Bryan Evenson
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