On Thu, Sep 21, 2017 at 05:18:12PM +0100, Martyn Welch wrote: > From: Nandor Han <nandor.han@xxxxxx> > > The CTSC and CTS bits affect operation of the CTS/RTS hardware flow > control signal (depending on whether the device is in DCE or DTE mode) and > are not related to DMA. When in RS-232 mode, the driver is using the > automatic CTSC control based on a rxFIFO fill level unless the state of > the CTS signal is explictly set via an ioctl call. > > Previous improvements to the imx serial driver have resulted on > imx_disable_dma() only being called on shutdown, by which point the > serial core has already correctly deasserted CTS. > > Testing shows that without this handling in imx_disable_dma() the CTS > signal state is set correctly when the device is open and TIOCM_RTS is > set/cleared via the TIOCMGET ioctl. The CTS signal is also correctly > deasserted when the device file is closed. With that block kept CTS set once more to inactive. So the block doesn't hurt and is "only" superflous, right? > When in RS-485 mode, the driver uses the CTS signal very differently and > appears to control it via calls to imx_port_rts_active() and > imx_port_rts_inactive(). > > This configuration of the CTSC and CTS bits are therefore not needed. > > Signed-off-by: Nandor Han <nandor.han@xxxxxx> > Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx> > Signed-off-by: Martyn Welch <martyn.welch@xxxxxxxxxxxxxxx> > --- > drivers/tty/serial/imx.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > index fe368a4..d90dae3 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -1225,11 +1225,6 @@ static void imx_disable_dma(struct imx_port *sport) > temp &= ~(UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN); > writel(temp, sport->port.membase + UCR1); > > - /* clear UCR2 */ > - temp = readl(sport->port.membase + UCR2); > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN); > - writel(temp, sport->port.membase + UCR2); The commit log doesn't mention ATEN, I guess that one just doesn't matter any more at this stage? Would be nice to point out though. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- 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
