Messages in this thread Patch in this message |  | | | Date | Wed, 16 Dec 2009 17:14:53 -0800 | | From | Greg KH <> | | Subject | [42/90] Serial: Do not read IIR in serial8250_start_tx when UART_BUG_TXEN |
| |
2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Ian Jackson <ian.jackson@eu.citrix.com>
commit 68cb4f8e246bbbc649980be0628cae9265870a91 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/serial/8250.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/drivers/serial/8250.c +++ b/drivers/serial/8250.c @@ -1337,14 +1337,12 @@ static void serial8250_start_tx(struct u 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); } }
|  |