(Sorry for the resend, I forgot to cc the list)
Hi Russell,
It seems that the following change in drivers/serial/8250.c
+
+ /*
+ * Do a quick test to see if we receive an
+ * interrupt when we enable the TX irq.
+ */
+ serial_outp(up, UART_IER, UART_IER_THRI);
+ lsr = serial_in(up, UART_LSR);
+ iir = serial_in(up, UART_IIR);
+ serial_outp(up, UART_IER, 0);
+
+ if (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT) {
+ if (!(up->capabilities & UART_BUG_TXEN)) {
+ up->capabilities |= UART_BUG_TXEN;
+ pr_debug("ttyS%d - enabling bad tx status workarounds\n",
+ port->line);
+ }
+ } else {
+ up->capabilities &= ~UART_BUG_TXEN;
+ }
+
that was introduced in 2.6.12[1], is causing oopses on some hardware. In
particular Jose Goncalves reported[2] an oops in 2.6.16.38 reproducible
(after a few days of open()/close() on the serial port). He bisected this
to that change -thanks for the long debugging Jose ;)-. and reverting
that part of the 2.6.12 git patch seems to fix the problem.
I was wondering:
- what is the goal of the test?
- could this be CONFIGed ?
Regards,
Frederik
PS: CCing Andrew and Zang Roy-r61911 as they seemed to discuss this in
http://lkml.org/lkml/2006/6/13/21
[1]http://lkml.org/lkml/2005/6/23/266
[2]http://lkml.org/lkml/2007/1/26/157
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