From 658a16c5128f57964cb71a86b893b462cd0e2467 Mon Sep 17 00:00:00 2001 From: Oliver Barta Date: Wed, 19 Jun 2019 10:16:39 +0200 Subject: [PATCH] Revert "serial: 8250: Don't service RX FIFO if interrupts are disabled" 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 Reviewed-by: Andy Shevchenko Fixes: 2e9fe5391083 ("serial: 8250: Don't service RX FIFO if interrupts are disabled") Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index ecf3d631bc09..ab0796d14ac1 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1873,8 +1873,7 @@ 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); } -- 2.20.1