[PATCH 23/58] Serial: Do not read IIR in serial8250_start_tx when UART_BUG_TXEN
From: Greg Kroah-Hartman
Date: Fri Dec 11 2009 - 18:29:52 EST
From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Do not read IIR in serial8250_start_tx when UART_BUG_TXEN
Reading the IIR clears some oustanding interrupts so it is not safe.
Instead, simply transmit immediately if the buffer is empty without
regard to IIR.
Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Reviewed-by: Markus Armbruster <armbru@xxxxxxxxxx>
Reviewed-by: Jiri Kosina <jkosina@xxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/serial/8250.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index b75e63e..c3e37c8 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1339,14 +1339,12 @@ static void serial8250_start_tx(struct uart_port *port)
serial_out(up, UART_IER, up->ier);
if (up->bugs & UART_BUG_TXEN) {
- unsigned char lsr, iir;
+ unsigned char lsr;
lsr = serial_in(up, UART_LSR);
up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
- iir = serial_in(up, UART_IIR) & 0x0f;
if ((up->port.type == PORT_RM9000) ?
- (lsr & UART_LSR_THRE &&
- (iir == UART_IIR_NO_INT || iir == UART_IIR_THRI)) :
- (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT))
+ (lsr & UART_LSR_THRE) :
+ (lsr & UART_LSR_TEMT))
transmit_chars(up);
}
}
--
1.6.5.5
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