Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.2 26/61] Revert "serial: 8250: Dont service RX FIFO if interrupts are disabled" | Date | Fri, 12 Jul 2019 14:19:39 +0200 |
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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); }
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