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authorIan Jackson <ian.jackson@eu.citrix.com>2009-11-18 05:08:11 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-12-11 18:18:05 -0500
commit68cb4f8e246bbbc649980be0628cae9265870a91 (patch)
treeac21578ae76e640af2584726a80c20673f25ef1a /drivers/serial
parent7e11a0fb3b7ab83871b7a56c7a67c603283ec4b9 (diff)
Serial: Do not read IIR in serial8250_start_tx when UART_BUG_TXEN
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@eu.citrix.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Jiri Kosina <jkosina@suse.cz> Cc: Alan Cox <alan@linux.intel.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/serial')
-rw-r--r--drivers/serial/8250.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index b75e63e9d1ee..c3e37c8e7e26 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1339,14 +1339,12 @@ static void serial8250_start_tx(struct uart_port *port)
1339 serial_out(up, UART_IER, up->ier); 1339 serial_out(up, UART_IER, up->ier);
1340 1340
1341 if (up->bugs & UART_BUG_TXEN) { 1341 if (up->bugs & UART_BUG_TXEN) {
1342 unsigned char lsr, iir; 1342 unsigned char lsr;
1343 lsr = serial_in(up, UART_LSR); 1343 lsr = serial_in(up, UART_LSR);
1344 up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS; 1344 up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
1345 iir = serial_in(up, UART_IIR) & 0x0f;
1346 if ((up->port.type == PORT_RM9000) ? 1345 if ((up->port.type == PORT_RM9000) ?
1347 (lsr & UART_LSR_THRE && 1346 (lsr & UART_LSR_THRE) :
1348 (iir == UART_IIR_NO_INT || iir == UART_IIR_THRI)) : 1347 (lsr & UART_LSR_TEMT))
1349 (lsr & UART_LSR_TEMT && iir & UART_IIR_NO_INT))
1350 transmit_chars(up); 1348 transmit_chars(up);
1351 } 1349 }
1352 } 1350 }