From: Oliver Barta o.barta89@gmail.com
commit 3f2640ed7be838c3f05c0d2b0f7c7508e7431e48 upstream.
This reverts commit 2e9fe539108320820016f78ca7704a7342788380.
Reading LSR unconditionally but processing the error flags only if UART_IIR_RDI bit was set before in IIR may lead to a loss of transmission error information on UARTs where the transmission error flags are cleared by a read of LSR. Information are lost in case an error is detected right before the read of LSR while processing e.g. an UART_IIR_THRI interrupt.
Signed-off-by: Oliver Barta o.barta89@gmail.com Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Fixes: 2e9fe5391083 ("serial: 8250: Don't service RX FIFO if interrupts are disabled") Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/tty/serial/8250/8250_port.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1869,8 +1869,7 @@ int serial8250_handle_irq(struct uart_po
status = serial_port_in(port, UART_LSR);
- if (status & (UART_LSR_DR | UART_LSR_BI) && - iir & UART_IIR_RDI) { + if (status & (UART_LSR_DR | UART_LSR_BI)) { if (!up->dma || handle_rx_dma(up, iir)) status = serial8250_rx_chars(up, status); }