Dear Torsten Fleischer, > Dear Marek Vasut, > > > > Large EEPROMs, e.g. 24lc32, need 2 byte to address the internal memory. > > > These devices require that the high byte of the internal address has to > > > be written first. > > > The mxs_i2c driver currently writes the address' low byte first. > > > > Are you sure about it? Are you sure what you're seeing isn't FIFO > > overrun? > > Yes, because I used 'i2c md' and 'i2c mw' for the test and these commands > do only a small write transfer. They write 3 and 4 bytes respectively. > This is in both cases only one FIFO word. > > > Basically, how does your problem manifest? How did you test this? > > First I wrote different bytes into the addresses 0x00 and 0x01 of the > EEPROM using 'i2c mw', for example: > > => i2c mw 54 0.2 12 > => i2c mw 54 1.2 34 > > Then I read the address range 0x00 - 0x01 and got: > > => i2c md 54 0.2 2 > 0000: 12 ff .. > > That's not what I had expected. On address 0x01 there should be '34' > instead of 'ff'. > But when I read directly from the address 0x01 the command returned the > correct value: > > => i2c md 54 1.2 1 > 0001: 34 4 > > Thereupon I checked the I2C frame of the read and write commands to the > address 0x01 with an oscilloscope. The scope showed that after the device's > address the bytes 0x01 followed by 0x00 were sent to the EEPROM. But the > two bytes must be in reverse order. > > After inspecting the source code I swapped the address bytes, i.e. I used > '100.2' instead of '1.2'. With it the read/write command accessed the > address 0x01 of the EEPROM. I verified this with the scope. > > Reading the range 0x00 - 0x01 returned then the expected content: > > => i2c md 54 0.2 2 > 0000: 12 34 .4 > > I also tested the address byte swapping - before and after modifying the > driver - with other addresses (e.g. 0x0180 and 0x0fff) by checking the I2C > frames with the scope. > After fixing the driver, I additionally read the whole EEPROM using 'i2c > md' and verified the written addresses.
Oh this is very nice! Thanks a lot! Obviously: Acked-by: Marek Vasut <ma...@denx.de> > Best Regards > Torsten Fleischer Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
