Hi Grant,
I know this is old but I had marked this for re-review in my mail,
and after re-looking at this problem, I realized I gave you some bad info.
Since you were referring to uart_ops, I'll assume this is for your
serial-core mini-driver(s).
On 06/14/2013 11:46 AM, Peter Hurley wrote:
On 06/14/2013 11:17 AM, Grant Edwards wrote:
On 2013-06-14, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote:
On 06/12/2013 04:03 PM, Grant Edwards wrote:
I see the uart_ops.flush_buffer method which is used to flush the
UART's tx fifo (presumably when the user calls tcflush(TCOFLUSH)).
The N_TTY ldisc calls tty->ops->flush_buffer() for TCOFLUSH _and TCIOFLUSH_.
[ For a serial-core mini-driver, tty->ops->flush_buffer() is uart_flush_buffer(),
which calls uart_ops.flush_buffer().
]
How does the rx fifo get flushed when the user calls tcflush(TCIFLUSH)?
It doesn't.
The ioctl(TCIFLUSH) does in fact flush the tty buffers.
If you want to flush your hardware rx fifo, you can define the .ioctl()
method in your struct uart_ops and handle TCIFLUSH there.
Note: be sure to return -ENOIOCTLCMD so that TCIFLUSH processing still
gets seen by the ldisc!
Like this (apologies in advance for formatting; my mailer is dain-bramaged),
/* called with port->mutex held */
static int xxxxxx_ioctl(struct uart_port *port, unsigned int cmd,
unsigned long arg)
{
if (cmd == TCFLSH) {
switch (arg) {
case TCIFLUSH:
case TCIOFLUSH:
spin_lock_irq(&port->lock);
xxxxxx_empty_rx_fifo(port);
spin_unlock_irq(&port->lock);
/* fall-through */
}
}
return -ENOIOCTLCMD;
}
Sorry, hope this isn't too late :(
Regards,
Peter Hurley
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