From: Vignesh R Date: Thu, 8 Feb 2018 12:55:41 +0000 (+0530) Subject: serial: 8250: Don't service RX FIFO if interrupts are disabled X-Git-Tag: v4.17-rc1~125^2~57 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=2e9fe539108320820016f78ca7704a7342788380;p=uclinux-h8%2Flinux.git 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: Vignesh R Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 1328c7e70108..ffbb955d1c06 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -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); }