Commit 2e9fe539 authored by Vignesh R's avatar Vignesh R Committed by Greg Kroah-Hartman

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

Currently, data in RX FIFO is read based on UART_LSR register state even
if RDI and RLSI interrupts are disabled in UART_IER register.
This is because when IRQ handler is called due to TX FIFO empty event,
RX FIFO is serviced based on UART_LSR register status instead of
UART_IIR status. This defeats the purpose of disabling UART RX
FIFO interrupts during throttling(see, omap_8250_throttle()) as IRQ
handler continues to drain UART RX FIFO resulting in overflow of buffer
at tty layer.
Fix this by making sure that driver drains UART RX FIFO only when
UART_IIR_RDI is set along with UART_LSR_BI or UART_LSR_DR bits.
Signed-off-by: default avatarVignesh R <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 890fb16b
......@@ -1854,7 +1854,8 @@ 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)) {
if (status & (UART_LSR_DR | UART_LSR_BI) &&
iir & UART_IIR_RDI) {
if (!up->dma || handle_rx_dma(up, iir))
status = serial8250_rx_chars(up, status);
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