>>>>> "Michal" == Michal Simek <monstr@xxxxxxxxx> writes:
Hi,
Michal> Hi Peter,
Michal> sorry for delay. I had to look at another issue.
No problem.
Michal> Below is full log:
Michal> 1. I setup baudrate to 50. (It could be possible to set it up to 0 too)
Michal> That's why I think that doesn't matter what baudrate is setup.
Michal> 2. You see where ulite_startup is called. It is called only once.
Ok, good.
Michal> 3. You see that there is no call __uart_wait_until_sent(). It could be
Michal> called for ASYNC mode. The second thing is __uart_wait_until_sent
Michal> function is checking if tx fifo is empty not circ buffer is empty.
Yes, that's afaik what that function should do.
Michal> 4. Next thing is that in uart_close. port->count is 2 which means that
Michal> the executing path is
Michal> if (port->count) {
Michal> spin_unlock_irqrestore(&port->lock, flags);
Michal> goto done;
Michal> }
Michal> which means that there is no chance to call __uart_wait_until_sent
Michal> function anyway.
And no buffer flushing, so that's fine.
Michal> 5. I did one modification to add simple while loop till circ buffer is
Michal> empty to the same location to see what happen (timouts are bogus
Michal> values).
Michal> if (port->count) {
Michal> spin_unlock_irqrestore(&port->lock, flags);
Michal> printk("************ %x %x\n", (&uport->state->xmit)->tail,
Michal> (&uport->state->xmit)->head);
Michal> while (!uart_circ_empty(&uport->state->xmit)) {
Michal> msleep_interruptible(jiffies_to_msecs((uport->timeout - HZ/50)));
Michal> if (signal_pending(current))
Michal> break;
Michal> if (time_after(jiffies, jiffies + uport->timeout))
Michal> break;
Michal> }
Michal> printk("************\n");
Michal> goto done;
Michal> }
Ok, so this shows that there's still data in the circular buffer when
uart is closed, like expected.
For me, it all looks normal:
1. serial port gets opened, uart_open -> uart_startup -> ulite_startup
gets called, ASYNC_INITIALIZED gets set, circular buffer and hardware
TX fifo cleared.
2. Some time later serial port gets opened again, and uart_startup is a
NOP because ASYNC_INITIALIZED is set. No circular buffer / hw fifo
clear.
3. serial port gets closed, uart_close is a NOP because port->count > 0
4. serial port gets opened again, NOP like in 2.
The problem is the uart_flush_buffer() call we see after uart_open() in
4. If doesn't seem to come from serial_core (only called from uart_close
/ uart_hangup), so presumably it comes from the TTY core or
userspace. Could you add a bit more debug to figure out where exactly it
comes from?
Michal> ************
Michal> uart_open(0) called
Michal> uart_flush_buffer(0) called
--
Bye, Peter Korsgaard
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