Arnd Bergmann wrote: > On Thursday 11 October 2007, Valentine Barshak wrote: >> Currently find_legacy_serial_ports() can find no serial ports on the OPB. >> Thus no legacy boot console can be initialized. Just the early udbg console >> works, which is initialized with udbg_init_44x_as1() on the UART's physical >> address specified in kernel config. This happens because we look for ns16750 >> and higher serial devices only and expect opb node to have a device type >> property. This patch makes it look for ns16550 compatible devices and use >> of_device_is_compatible() for opb instead of checking device type. >> Lack of legacy serial ports found causes problems for KGDB over serial. >> >> Signed-off-by: Valentine Barshak <[EMAIL PROTECTED]> > > The patch would make sense if we were only dealing with flattened device > tree systems at this point. Unfortunately, IBM is shipping hardware that > encodes the serial port in exactly the way that find_legacy_serial_ports > is looking for (parent->type == "opb", compatible = "ns16750" "ns16550" > "ns16450" i8250"). > > Changing the search for ns16750 to ns16550 should be fine, but unnecessary > because AFAIK, all OPB serial imlpementations are actually ns16750 and > should have that in the device tree as well.
This is a bit odd. The docs say that uart chips on the ppc44x processors are registry-compatible to 16750, but have 16-byte FIFO's. This is OK for legacy serial stuff (since it really needs the chip to be 16550-compatible), but the 8250 driver expects 64-byte FIFO size for 16750. I guess that's why 44x uart dts entries don't have 16750 compatible property. > > For the device type of the bus, please check for both compatible and > type, so that it still works on machines that are missing the compatible > property. > > Arnd <>< _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
