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Re: [PATCH] MIPS: Octeon: Register EEPROM device on the I2C bus

To: Jean Delvare <khali@linux-fr.org>
Subject: Re: [PATCH] MIPS: Octeon: Register EEPROM device on the I2C bus
From: Yang Shi <yang.shi@windriver.com>
Date: Mon, 08 Mar 2010 12:43:47 +0800
Cc: Michael Lawnick <ml.lawnick@gmx.de>, Linux I2C <linux-i2c@vger.kernel.org>, linux-mips@linux-mips.org
In-reply-to: <20100305124200.6f6eccfc@hyperion.delvare>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1267772895-25409-1-git-send-email-yang.shi@windriver.com> <20100305071130.GB21925@pengutronix.de> <4B90B341.9000601@windriver.com> <20100305074155.GD21925@pengutronix.de> <4B90B888.6060005@windriver.com> <20100305095040.6ab4612c@hyperion.delvare> <4B90D85E.6040308@gmx.de> <4B90DF48.50005@windriver.com> <20100305115213.4b504710@hyperion.delvare> <4B90E83A.5020106@gmx.de> <20100305124200.6f6eccfc@hyperion.delvare>
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Jean Delvare 写道:
Hi Michael,

On Fri, 05 Mar 2010 12:17:14 +0100, Michael Lawnick wrote:
Jean Delvare said the following:
Well, what EEPROM type do you have exactly? 24c64 is for 64 kbit (8
kByte) EEPROMs using 16-bit addressing. You must use the correct type,
otherwise the at24 driver will misbehave. I am a little surprised
because originally you went for "eeprom" which is not compatible with
"24c64" (8-bit vs. 16-bit addressing).
Furthermore this brings up another issue:
0x50 typically is SPD-eeprom (DDR initialisation). Corrupting the
contents might make your board unbootable - and using a 16bit driver
instead of an 8-bit one can corrupt your contents already on
(positioned) reading!

This is totally correct, but better said loud to the list and the
original poster than only privately to me ;)

Thanks a lot to point out this.

I double checked the manual, the eeprom is SPD of the DIMMs.

I will rework my patch, then send V2 soon.

Regards,
Yang



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