On Thu, 2007-10-11 at 21:26 +0400, Valentine Barshak wrote: > Josh Boyer wrote: > > On Thu, 2007-10-11 at 17:50 +0200, 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. > >> > >> 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. > > > > Wait, no. We already had this discussion months ago when David was > > working on the original Ebony port. It was declared that legacy_serial > > is not how serial should be done on 4xx and the serial_of driver was > > supposed to be used instead. > > > > Have we changed our stance on that? If not, then perhaps KGDB should be > > fixed to work with serial_of. > > Actually I don't see any reason not to use legacy_serial stuff for early > console. We could split the kernel configured very early debug output, > which uses PPC_EARLY_DEBUG_44x_PHYSLOW/PHYSHIGH (since it's really > dangerous) and early console things by using legacy serial. We could use > early boot console without PPC_EARLY_DEBUG_44x.
That was exactly my thinking when this first came up. I'd like to hear David's opinion on it. josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
