From mboxrd@z Thu Jan 1 00:00:00 1970 From: Munir Bandukwala Subject: Re: Writing to AT24C64C EEPROM fails on RHEL based kernels Date: Mon, 07 Mar 2011 12:48:39 -0800 Message-ID: <4D7544A7.3090509@riverbed.com> References: <4D753233.8060208@riverbed.com> <20110307194819.GA17883@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110307194819.GA17883-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Wolfram Sang Cc: Munir Bandukwala , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-i2c@vger.kernel.org Thanks Wolfram for your response, my comments are inline ... On 03/07/2011 11:48 AM, Wolfram Sang wrote: >> While looking for patches, I came accross >> https://bugzilla.redhat.com/show_bug.cgi?id=182687 and adding an extra delay >> in the piix4_transaction function fixes the problem for me as well. > So, this is not a problem anymore if I understand you correctly? > yes thats correct, I have to add a delay for the chip on my box (its not the same as the one used in the patch above) and it works, what I was wondering was why ubuntu/2.6.35 works without the additional delay or any changes to code. >> I think the problems are related, but any pointers would be appreciated. I am >> pasting information about my machine, please let me know if you guys needs >> any more information > This seems normal to me. The eeprom needs time to write the data. Any reasons > for not using the in-kernel eeprom driver (drivers/misc/eeprom/at24.c)? It > deals with all of that (and probably more). > I did try the at24 driver and had a similar issue, for ease of testing and comparing different kernels, I switched to the user space code. > Regards, > > Wolfram >