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Revert "serial: 8250: Don't service RX FIFO if interrupts are disabled"

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This reverts commit 2e9fe53910.

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: 2e9fe53910 ("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>
This commit is contained in:
Oliver Barta 2019-06-19 10:16:39 +02:00 committed by Greg Kroah-Hartman
parent 4a96895f74
commit 3f2640ed7b
1 changed files with 1 additions and 2 deletions
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3
drivers/tty/serial/8250/8250_port.c
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@ -1867,8 +1867,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
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);
}