Thanks, Florian. I found the cause of the problem. My board is 32 bit based, so each serial port register is 32bit even only 8 bit is used. So when the board is switched endianess, I need to change the address offset to access the same registers. For example, original RHR register address is 0x8001000 with little endian mode. With big endian, I need to access it as 0x8001003. On Tue, 20 Oct 2009 08:17 +0200, "Florian Fainelli" <florian@xxxxxxxxxxx> wrote: > Hi, > > Le mardi 20 octobre 2009 01:56:04, myuboot@xxxxxxxxxxx a écrit : > > I am trying to bringup a MIPS32 board using 2.6.31. It is working in > > little endian mode. After changing the board's hardware from little > > endian to bit endian, the serial port print messed up. It prints now > > something like - "àààààààààààààààà" on the screen. When I trace the > > execution, I can see the string the kernel is trying print is correct - > > "Linux version 2.6.31 ..." and etc. > > > > I guess it means the initialization of the serial port is not properly > > done. But I am not sure where I should check for the problem. The serial > > port device I am using is 8250. Please give me some advise. > > If the same initialization routine used to work in little-endian, check > how > you actually write and read characters from the UART FIFO and especially > if > your hardware requires you to do word or byte access to these registers. > > You can have a look at AR7, which has the same code working for Little > and Big > Endian modes in arch/mips/ar7/prom.c lines 272 to the end of the file. It > also > uses a 8250-compatible UART.
