On Wed, Nov 12, 2014 at 1:04 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Wednesday 12 November 2014 00:46:30 Kevin Cernekee wrote: >> Remove the platform dependency in Kconfig and add an appropriate >> compatible string. Note that BCM7401 has one 16550A-compatible UART >> in the UPG uart_clk domain, and two proprietary UARTs in the 27 MHz >> clock domain. This driver handles the former one. >> >> Signed-off-by: Kevin Cernekee <cernekee@xxxxxxxxx> > > Can you explain why you are using the PXA serial driver instead of the > 8250 driver, if this is 16550A compatible? I don't know the history > why PXA is using a separate driver. I wasn't able to get serial8250 to work in any situation where another driver tried to claim "ttyS"/4/64. serial8250 calls uart_add_one_port() in its module_init function, even if the system doesn't have any ports. Setting nr_uarts (CONFIG_SERIAL_8250_RUNTIME_UARTS) to 0 doesn't help because serial8250_find_match_or_unused() will just return NULL. I guess I could try to rework that logic but several cases would need to be retested, going back to PCs with ISA buses and PCI add-in cards. And the differences may be visible to userspace. The PXA driver seemed like a much cleaner starting point, even if it was intended for a different SoC.
