[PATCH 03/16] tty: serial: 8250_core: read only RX if there is something in the FIFO

On 02/12/2015 08:55 PM, Peter Hurley wrote:

On 02/12/2015 02:23 PM, Sebastian Andrzej Siewior wrote:

quoted

* Peter Hurley | 2015-02-12 11:32:04 [-0500]:

quoted

That said, I don't think serial8250_do_startup() is really doing that much
for OMAP h/w startup; open-coding what omap_8250 really needs is probably
< 10 loc.

10 loc? I have a few more.

:)

quoted

serial8250_clear_fifos(),
serial_link_irq_chain() aren't exported. serial8250_set_mctrl() can
maybe accessed via uart_ops->set_mctrl(). Maybe I'm not removing the
obvious not required code but here it looks better to just a BUG flag for
the Omap.

Ok.

Okay. I will try to post something tomorrow.

quoted

--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
+
+	/*
+	 * Clear the interrupt registers.
+	 */
+	if (serial_port_in(port, UART_LSR) & UART_LSR_DR)
+		serial_port_in(port, UART_RX);
+	serial_port_in(port, UART_IIR);
+	serial_port_in(port, UART_MSR);
+
+	retval = serial_link_irq_chain(up);
+	if (retval)
+		goto out;

omap doesn't really need the legacy irq chain handling; this could just be
request_irq().

In the 8250 split I'll be posting soon, all the irq chaining and
polling-via-timeout workarounds stays in the universal/legacy driver so
other 8250 drivers can opt-out.

Ah. This sounds interesting.

Sebastian