On Mon, 13 Aug 2007, Scott Wood wrote:

Guennadi Liakhovetski wrote:

quoted

# ls -l /sys/devices/platform/serial8250.0/tty*
lrwxrwxrwx 1 root root 0 Aug 13 22:05
/sys/devices/platform/serial8250.0/tty:ttyS0 -> ../../../class/tty/ttyS0
lrwxrwxrwx 1 root root 0 Aug 13 22:05
/sys/devices/platform/serial8250.0/tty:ttyS1 -> ../../../class/tty/ttyS1

And placing some wakeup file under the class/tty/ directory doesn't seem
very consistent with the current policy - until now they only live under
devices/... (Greg added to cc:).

Hmm... I'd assumed each port would have its own device directory.  Would
anything break horribly if it were changed so that each tty:ttySx is a
directory, which contains both a wakeup file and the symlink?

Yeah, I'd love to know the answer too:-) As you see, atm it is one 
platform device as defined in arch/powerpc/kernel/legacy_serial.c:

static struct platform_device serial_device = {
	.name	= "serial8250",
	.id	= PLAT8250_DEV_PLATFORM,
	.dev	= {
		.platform_data = legacy_serial_ports,
	},
};

with a list of ports in platform data:

static struct plat_serial8250_port legacy_serial_ports[MAX_LEGACY_SERIAL_PORTS+1];

Hence one device directory. Same on a PC

$ ls -l /sys/devices/platform/serial8250/tty*
lrwxrwxrwx  1 root root 0 Aug 13 23:10 /sys/devices/platform/serial8250/tty:ttyS0 -> ../../../class/tty/ttyS0
lrwxrwxrwx  1 root root 0 Aug 13 23:10 /sys/devices/platform/serial8250/tty:ttyS1 -> ../../../class/tty/ttyS1
lrwxrwxrwx  1 root root 0 Aug 13 23:10 /sys/devices/platform/serial8250/tty:ttyS2 -> ../../../class/tty/ttyS2
lrwxrwxrwx  1 root root 0 Aug 13 23:10 /sys/devices/platform/serial8250/tty:ttyS3 -> ../../../class/tty/ttyS3

You should get the interrupt, but not until after the PM code enables IRQs.
Are you saying that the interrupt handler runs before then?

Great, it is working correctly then! Don't think the ISR runs return from 
PM, no.

Thanks
Guennadi
---
Guennadi Liakhovetski