I have had problems with I2C slave devices keeping the data line low if the communications to them is interrupted, say by a missing clock when they are outputting a 0 on the data line. Then the Davinci chip thinks there is a bus conflict and does not re-try. I added code at the start of the driver to change the CLK line to a GPIO and toggle it 10 times and then convert it back to I2C Clk. This clocks all devices on the bus and forces the stuck I2C slave to finish clocking out the rest of the data. My code does this only after some number of failed tries.
Attached is my patch. I am still using kernel version 2.6.10. There are a number of other changes to the file that I had to do to make it work reliably with our system Also note that I changed the speed from 40 KHZ (required to talk to the eMSP430) to 100 KHZ.. The speed can be changed to 400 but we have a device that limited us to 100. Mike Rondeau _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Prabhaharan R-TLS,Chennai Sent: Thursday, December 04, 2008 11:43 AM To: davinci-linux-open-source Cc: Balaji Raj R-TLS, Chennai.; Madhavan Vivekanandan; Manohar S-TLS, Chennai. Subject: Davinci DMS355 - I2C communication issue Importance: High Hello All, I am facing an issue in the I2C communication in the Davinci Dm355 processor. We have taken the Montavista TI Davinci code as the base. In that, we have MSP430 device. But, in our case, we have made a custom based board that don't have MSP430 device. Processor will always acts as a master and the other devices connected to the processor will work as the slave. As per our board design, we need the I2C data line to be high always for successful communication. But, the Montavista TI Davinci Linux code reset this line to zero as till the kernel gets booted the I2C data line is high. Hence we don't know, what makes the I2C data line to low! Does anyone face the similar issue? Please reply. Thanks a lot in advance. Regards, Prabhaharan.R DISCLAIMER: ------------------------------------------------------------------------ ----------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. It shall not attach any liability on the originator or HCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any mail and attachments please check them for viruses and defect. ------------------------------------------------------------------------ ----------------------------------------------- ------------------------------------------------------------------------------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. If you have received it in error, please notify the sender immediately and delete the original. Any unauthorized use of this email is prohibited. ------------------------------------------------------------------------------------------------ [mf2]
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