Commit 658a16c5 authored by Oliver Barta's avatar Oliver Barta Committed by Greg Kroah-Hartman

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

commit 3f2640ed7be838c3f05c0d2b0f7c7508e7431e48 upstream.

This reverts commit 2e9fe539.

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: default avatarOliver Barta <>
Reviewed-by: default avatarAndy Shevchenko <>
Fixes: 2e9fe539 ("serial: 8250: Don't service RX FIFO if interrupts are disabled")
Cc: stable <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 771340b0
......@@ -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);
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