From: Oliver Barta <o.barta89@gmail.com>
Date: Wed, 19 Jun 2019 08:16:39 +0000 (+0200)
Subject: Revert "serial: 8250: Don't service RX FIFO if interrupts are disabled"
X-Git-Tag: v5.4-rc1~601^2~13
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3f2640ed7be838c3f05c0d2b0f7c7508e7431e48;p=platform%2Fkernel%2Flinux-rpi.git

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

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>
---

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index a6fabc7..c1cec80 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -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);
 	}