On Wed, Feb 01, 2006 at 10:45:49AM -0500, George G. Davis wrote:
> But uart_add_one_port() intentionally does not spin_lock_init() the
> port.lock of the serial console device under the assumption that
> it is already done.
Yes, and there's a bug in there atm...
> Here's the call sequence:
>
> start_kernel()
> ...
> console_init()
> ...
> serial8250_console_init()
> serial8250_isa_init_ports()
> if (first)
> spin_lock_init() /* port.lock init */
> ...
>
> All 8250 serial port.locks are now initialised but no ports have
> been registered (on targets which do not register legacy serial ports
> via old_serial_port[]) at this point.
This initialisation is actually pointless here.
>
> register_console()
> serial8250_console_setup() /* -ENODEV */
> ...
> rest_init()
> ...
> /* arch_initcalls */
> early_serial_setup()
This is where it goes wrong. Don't call early_serial_setup() after
"early". Use a platform device instead.
I absolutely detest the number of ways to initialise an 8250 port -
I'd like there to be only one way, but that doesn't satisfy everyone.
That one way is via platform devices. Please use that method in
preference to everything else, _especially_ from architecture code.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
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