| Message ID | 1506010697-22114-2-git-send-email-martyn.welch@collabora.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Sep 21, 2017 at 05:18:12PM +0100, Martyn Welch wrote: > From: Nandor Han <nandor.han@ge.com> > > 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@ge.com> > Signed-off-by: Romain Perier <romain.perier@collabora.com> > Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk> > --- > 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
On Thu, Sep 21, 2017 at 08:20:17PM +0200, Uwe Kleine-König wrote: > On Thu, Sep 21, 2017 at 05:18:12PM +0100, Martyn Welch wrote: > > From: Nandor Han <nandor.han@ge.com> > > > > 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? > That's my understanding, yes. > > 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@ge.com> > > Signed-off-by: Romain Perier <romain.perier@collabora.com> > > Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk> > > --- > > 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. > Hmm, going to need to look at this again... Patch 5 adds clearing ATEN into imx_stop_rx(), which is sensible given that it's the aging timer on the rxFIFO, but I don't think we should be removing that from here before it's in imx_stop_rx(). > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | http://www.pengutronix.de/ |
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); - imx_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT); sport->dma_is_enabled = 0;