Hello Laurent, on Thu, 18 May 2006 14:33:58, Laurent Pinchart wrote: > I'm trying to use the MPC8248 hardware I2C bus in a 2.6.16 kernel. The > mailing > list archives mention a driver for the MPC8260 > (http://ozlabs.org/pipermail/linuxppc-embedded/2006-May/022837.html) which I > modified to reflect the memory map differences between the MPC8260 and the > MPC8248, as mentionned in the e-mail. > > The good news is that the driver works. The bad news is that it doesn't work
OK. > correctly. :-( > The Linux I2C layer probes the I2C bus for peripherals when drivers are > loaded. The probing function writes a single byte with the device address and > check if the data is acked. I monitored the SCL and SDA lines using an [...] > Using that code, no data is sent on the bus, the BD_SC_READY bit is never > cleared and no interrupt is generated. Once again I suspected a CPM bug when > writing a single byte on the bus, so I increased cbd_datlen to 2: > > tbdf[0].cbd_bufaddr = __pa(tb); > tbdf[0].cbd_datlen = 2; > tbdf[0].cbd_sc = count ? BD_SC_READY | BD_IIC_START : > BD_SC_READY | BD_IIC_START | BD_SC_INTRPT | > BD_SC_LAST | BD_SC_WRAP; > > This worked, and two bytes were written on the bus, leading me to believe > that > the CPM was at fault. I don t know, if this is a CPM Bug, but it seems so to me ... > Has anyone noticed the same behaviour ? Is there a workaround available ? I > tried searching Freescale's website for CPM microcode updates but haven't > found anything related to the I2C controller. Yes, Holger Speck had the same problem. He solved it by doing the following: If the cpm_iic_write is called with count = 0. He made a read with count = 1 I think this is safer than writing 2 Bytes to the Slave. Could you try this? Best regards Heiko
