[ forget to copy this to l-u-u. jcb ] >On Fri, Dec 09, 2005 at 04:42:35PM +0000, Julian Bradfield wrote: >> Under 2.6.12, I can see the DCD line changing with TIOCMGET, but if I >> try to wait for it with TIOCMIWAIT, I wait for ever. > >It should work, but I don't know if it's been tested in a long time. If >you could load the driver with: > modprobe debug=1 > >and send us the kernel log for when you try to test this.
Ah. Having asked the system staff to switch this on, all is made clear. Here's what happens at the MIWAIT, and when I assert DCD : drivers/usb/serial/pl2303.c: pl2303_ioctl (0) TIOCMIWAIT drivers/usb/serial/pl2303.c: pl2303_read_int_callback (0) PL-2303 ttyUSB0: pl2303_read_int_callback - length = 10, data = a1 20 00 00 00 00 02 00 01 00 drivers/usb/serial/pl2303.c: pl2303_read_int_callback (0) PL-2303 ttyUSB0: pl2303_read_int_callback - length = 10, data = a1 20 00 00 00 00 02 00 00 00 Now looking at the code explains it. In the latest 2.4 kernels, read_int_callback does some status saving, and then wakes up the delta_msr_wait queue. In the latest 2.6 kernels, read_int_callback calls pl2303_update_line_status to do the status saving, but neither read_int_callback nor pl2303_update_line_status wakes up the delta_msr_wait queue. So I suppose the only question is, where should the wake-up go? ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
