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[SERIAL] don't disable xscale serial ports after autoconfig 

xscale-type UARTs have an extra bit (UUE) in the IER register that has
to be written as 1 to enable the UART.  At the end of autoconfig() in
drivers/serial/8250.c, the IER register is unconditionally written as
zero, which turns off the UART, and makes any subsequent printch() hang
the box.

Since other 8250-type UARTs don't have this enable bit and are thus
always 'enabled' in this sense, it can't hurt to enable xscale-type
serial ports all the time as well.  The attached patch changes the
autoconfig() exit path to see if the port has an UUE enable bit, and if
yes, to write UUE=1 instead of just putting a zero into IER, using the
same test as is used at the beginning of serial8250_console_write().

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
hifive-unleashed-5.1
Lennert Buytenhek 2005-11-12 21:58:05 +00:00 committed by Russell King
parent cd52d1ee9a
commit 5c8c755ce5
1 changed files with 4 additions and 1 deletions
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5
drivers/serial/8250.c
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@ -999,7 +999,10 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
serial_outp(up, UART_MCR, save_mcr);
serial8250_clear_fifos(up);
(void)serial_in(up, UART_RX);
serial_outp(up, UART_IER, 0);
if (up->capabilities & UART_CAP_UUE)
serial_outp(up, UART_IER, UART_IER_UUE);
else
serial_outp(up, UART_IER, 0);
out:
spin_unlock_irqrestore(&up->port.lock, flags);