From a722dec72d10fb1e64d3a1458e4c4433588f3706 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Sun, 15 Feb 2015 18:32:16 +0100 Subject: [PATCH] serial: 8250: Revert "tty: serial: 8250_core: read only RX if there is something in the FIFO" This reverts commit a7bab22f2adc48e42c8fd524bafe21679c81b5ce. The conditional RX-FIFO read seems to cause spurious interrupts and we see just: |serial8250: too much work for irq29 The previous behaviour was "default" for decades and Marvell's 88f6282 SoC might not be the only that relies on it. Therefore the Omap fix is reverted for now. Fixes: a7bab22f2adc ("tty: serial: 8250_core: read only RX if there is something in the FIFO") Reported-By: Nicolas Schichan Debuged-By: Peter Hurley Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_core.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index e3b9570a1eff8..deae122c9c4ba 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -2138,8 +2138,8 @@ int serial8250_do_startup(struct uart_port *port) /* * Clear the interrupt registers. */ - if (serial_port_in(port, UART_LSR) & UART_LSR_DR) - serial_port_in(port, UART_RX); + serial_port_in(port, UART_LSR); + serial_port_in(port, UART_RX); serial_port_in(port, UART_IIR); serial_port_in(port, UART_MSR); @@ -2300,8 +2300,8 @@ dont_test_tx_en: * saved flags to avoid getting false values from polling * routines or the previous session. */ - if (serial_port_in(port, UART_LSR) & UART_LSR_DR) - serial_port_in(port, UART_RX); + serial_port_in(port, UART_LSR); + serial_port_in(port, UART_RX); serial_port_in(port, UART_IIR); serial_port_in(port, UART_MSR); up->lsr_saved_flags = 0; @@ -2394,8 +2394,7 @@ void serial8250_do_shutdown(struct uart_port *port) * Read data port to reset things, and then unlink from * the IRQ chain. */ - if (serial_port_in(port, UART_LSR) & UART_LSR_DR) - serial_port_in(port, UART_RX); + serial_port_in(port, UART_RX); serial8250_rpm_put(up); del_timer_sync(&up->timer); -- 2.39.5