Problem with 8250 suspend/resume

Problem with 8250 suspend/resume

[Marco Cavallini]

Hello,
I am testing suspend/resume using ttyS ports,
but I am facing to problems with 8250 based ports.
Linux kernel is 2.6.17-rc4 (but I've noticed no changes in 2.6.18)

Serial ports are 16C2852 but are identified as XR16850.

If I send the board to sleep and I try to wake it with chars from ttyS3 
( or ttyS*) the system go in suspend mode ans NEVER wakes up using 
serial ports:
# cat /dev/ttyS3 &
# echo standby > /sys/power/state

I tried also putting a function  enable_irq_wake(port->irq)
at the end of uart_suspend_port() [file drivers/serial/serial_core.c]
and in that case when I do the suspend command
# echo standby > /sys/power/state
immediately wakes up with no events and no interrupts rised from UART 
chip, with no cable connected to any port except console ttyAT0

I have been working on this problem for almost a week without success,
using printk and trying to understand what is going wrong.

If anybody has been experienced with 8250 suspend/resume problems or 
knows if there is something bad into the driver, I 'd like a hint to 
understand what to do.

Any hint will be greatly appreciated
Thanks
-- 
Marco Cavallini
Koan s.a.s. - Bergamo - ITALIA
Embedded and Real-Time Software Engineering
  - Atmel Third Party Consultant
Tel. +39-(0)35-255.235 - Fax +39-178-223.9748
www.KoanSoftware.com   |    www.KaeilOS.com