On Fri, May 30, 2014 at 07:52:25AM +0200, Dirk Behme wrote: > On 23.05.2014 06:32, Huang Shijie wrote: > >This patch disables the receiver ready interrupt for imx_stop_rx. > >It reduces the interrupt numbers when the uart is going to close > >or suspend. > > > >Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx> > >--- > > drivers/tty/serial/imx.c | 4 ++++ > > 1 files changed, 4 insertions(+), 0 deletions(-) > > > >diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > >index ed6cdf7..6026101 100644 > >--- a/drivers/tty/serial/imx.c > >+++ b/drivers/tty/serial/imx.c > >@@ -440,6 +440,10 @@ static void imx_stop_rx(struct uart_port *port) > > > > temp = readl(sport->port.membase + UCR2); > > writel(temp & ~UCR2_RXEN, sport->port.membase + UCR2); > >+ > >+ /* disable the `Receiver Ready Interrrupt` */ > >+ temp = readl(sport->port.membase + UCR1); > >+ writel(temp & ~UCR1_RRDYEN, sport->port.membase + UCR1); > > Will this change cause a loss or a processing delay of RX characters > pending in the RX FIFO ? > > It is not clear whether disabling the receiver will clear the RX > FIFO. My guess is that the contents of the RX FIFO will remain > intact when the receiver is disabled. The RX interrupt has an > opportunity to mop up these pending characters in the RX FIFO but > disabling the RX interrupt has potential to leave those characters > in the RX FIFO. Does it matter ? When the @stop_rx() is called, the system(or the application) is closing or suspending, and it has decided to abandon the RX data. So i think it do not matter the RX FIFO has some left data. We will reset the RX FIFO when the UART port is re-started again. thanks Huang Shijie -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
