| Message ID | 20170705130706.10388-4-romain.perier@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Cc += Clemens Gruber + Fabio Estevam On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote: > From: Nandor Han <nandor.han@ge.com> > > CTSC and CTS are not related to DMA and might add > disruption in some cases. > > Signed-off-by: Romain Perier <romain.perier@collabora.com> If it was Nandor Han who created this patch, it would be great to get his sob. If it was you, drop the From: line above. > --- > 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 5291b86..dd3ebb4 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport) > imx_stop_rx_dma(sport); > imx_stop_tx_dma(sport); > > - /* clear UCR2 */ > - temp = readl(sport->port.membase + UCR2); > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN); > - writel(temp, sport->port.membase + UCR2); > - Before this patch imx_disable_dma resulted in the #CTS pin being high (inactive). Does this qualify as a fix? If so, you should sort this patch to the beginning of the series. Did you do test this patch and its effects separately? @Clemens: maybe this patch makes a relevant difference when the port is operated in rs485 mode. Do you care to test? > imx_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT); > > sport->dma_is_enabled = 0; > -- > 1.8.3.1 Best regards Uwe
Hi, On Wed, Jul 05, 2017 at 03:38:45PM +0200, Uwe Kleine-König wrote: > Cc += Clemens Gruber + Fabio Estevam > > On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote: > > From: Nandor Han <nandor.han@ge.com> > > > > CTSC and CTS are not related to DMA and might add > > disruption in some cases. > > > > Signed-off-by: Romain Perier <romain.perier@collabora.com> > > If it was Nandor Han who created this patch, it would be great to get > his sob. If it was you, drop the From: line above. > > > --- > > 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 5291b86..dd3ebb4 100644 > > --- a/drivers/tty/serial/imx.c > > +++ b/drivers/tty/serial/imx.c > > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport) > > imx_stop_rx_dma(sport); > > imx_stop_tx_dma(sport); > > > > - /* clear UCR2 */ > > - temp = readl(sport->port.membase + UCR2); > > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN); > > - writel(temp, sport->port.membase + UCR2); > > - > > Before this patch imx_disable_dma resulted in the #CTS pin being high > (inactive). > > Does this qualify as a fix? If so, you should sort this patch to the > beginning of the series. Did you do test this patch and its effects > separately? > > @Clemens: maybe this patch makes a relevant difference when the port is > operated in rs485 mode. Do you care to test? I just finished testing it. The results are about the same as with v1 of this patch series: Applying v2 of patch 1/6, 2/6 and 3/6 (or even 3/6 alone) does not fix the RS-485 DMA bug. It behaves exactly the same as without these patches, meaning the whole xmit circ_buf (UART_XMIT_SIZE bytes) is sent out, as seen in the logic analyzer screenshots from my first bug report: https://pqgruber.com/rs485_results.png Applying the whole series does make a (small) difference though: The first few transmissions after a fresh boot work correctly! However, after a few transmissions, characters are sent out twice and longer transmissions are garbled, although not in the same way as before. The whole circ_buf is no longer sent out. With all patches from this series applied, I see the following on the logic analyzer, when calling "echo Test > /dev/ttymxc4": https://pqgruber.com/rs485txtest.png (This pattern is not always the same, sometimes it is TeTesstt\n\n, sometimes TeTesst\nt\n or TeTsestt\n\n and so on) This behavior is reproducible on i.MX6Q and i.MX6D, not on i.MX6S/etc., I therefore assume that it is a SMP-/locking-related problem. I will try to debug this further, and verify if - with this series applied - xmit->tail is still jumping over xmit->head. And when exactly this is happening. Help is much appreciated! Best regards, Clemens
Hi On Wed, Jul 05, 2017 at 03:38:45PM +0200, Uwe Kleine-König wrote: > Cc += Clemens Gruber + Fabio Estevam > > On Wed, Jul 05, 2017 at 03:07:03PM +0200, Romain Perier wrote: > > From: Nandor Han <nandor.han@ge.com> > > > > CTSC and CTS are not related to DMA and might add > > disruption in some cases. > > > > Signed-off-by: Romain Perier <romain.perier@collabora.com> > > If it was Nandor Han who created this patch, it would be great to get > his sob. If it was you, drop the From: line above. > This patch was broken out from a larger one written by Nandor, who is happy for me to add his sob. > > --- > > 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 5291b86..dd3ebb4 100644 > > --- a/drivers/tty/serial/imx.c > > +++ b/drivers/tty/serial/imx.c > > @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport) > > imx_stop_rx_dma(sport); > > imx_stop_tx_dma(sport); > > > > - /* clear UCR2 */ > > - temp = readl(sport->port.membase + UCR2); > > - temp &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN); > > - writel(temp, sport->port.membase + UCR2); > > - > > Before this patch imx_disable_dma resulted in the #CTS pin being high > (inactive). > > Does this qualify as a fix? If so, you should sort this patch to the > beginning of the series. Did you do test this patch and its effects > separately? > I've been giving the RTS/CTS lines a bit of a kick with (and without) this patch and I'm seeing what I'd expect to see on the CTS pin (the Wandboard I'm using runs this in DCE mode even though it really should be in DTE mode, hey ho). Using a little test app I've found/modified (listed below), the CTS line can be (de)asserted whilst the device is open and the line gets deasserted when the device closes. I have tested this port both when acting as a console (and thus with DMA turned off) and when not used as a console, with DMA enabled (confirmed with existing debug in driver). This matches the behaviour of a FTDI based debug board that I've also tried (in this case I looked at the RTS line as the device is running as a DTE). On my PC the same test app sets the RTS line (the serial port running as a DTE, 8250_pnp driver) results in the CTS line being set appropriately as well. It also stays in that state even after the serial device is closed, this does seem right either but there you go. With regards to the operation of the CTS/RTS line when twiddling it via the ioctl, I think the behaviour of the IMX/FTDI is the expected one. Is that the case? Which I guess brings us to the lines above. When running as an RS232 port (i.e. not rs485) the driver is using the automatic CTSC control based on a rxFIFO watermark unless the state of the CTS line is explictly set via an ioctl call. As such, unless I'm missing something, the rxFIFO (and thus the automatic CTS control) is independent of whether the DMA is running or not and thus this section looks wrong or is at the very least in the wrong place. Have I misunderstood something? IIRC, the timing of DMA being enabled and disabled was changed reasonably recently did that fix the #CTS issue possibly? Martyn ---- Test app: #include <stdio.h> #include <stdlib.h> #include <termios.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdbool.h> static struct termios oldterminfo; void closeserial(int fd) { tcsetattr(fd, TCSANOW, &oldterminfo); if (close(fd) < 0) perror("closeserial()"); } int openserial(char *devicename) { int fd; struct termios attr; if ((fd = open(devicename, O_RDWR)) == -1) { perror("openserial(): open()"); return 0; } if (tcgetattr(fd, &oldterminfo) == -1) { perror("openserial(): tcgetattr()"); return 0; } attr = oldterminfo; attr.c_cflag |= CRTSCTS | CLOCAL; attr.c_oflag = 0; if (tcflush(fd, TCIOFLUSH) == -1) { perror("openserial(): tcflush()"); return 0; } if (tcsetattr(fd, TCSANOW, &attr) == -1) { perror("initserial(): tcsetattr()"); return 0; } return fd; } int setRTS(int fd, int level) { int status; if (ioctl(fd, TIOCMGET, &status) == -1) { perror("setRTS(): TIOCMGET"); return 0; } if (level) status |= TIOCM_RTS; else status &= ~TIOCM_RTS; if (ioctl(fd, TIOCMSET, &status) == -1) { perror("setRTS(): TIOCMSET"); return 0; } return 1; } int main(int argc, char *argv[]) { int fd; bool loop = true; int state = 1; int got; fd = openserial(argv[1]); if (!fd) { fprintf(stderr, "Error while initializing %s.\n", argv[1]); return 1; } while(loop) { printf("Switching RTS %s\n", state ? "on" : "off"); setRTS(fd, state); state = (++state) % 2; got = getchar(); if (got == 'q') break; } closeserial(fd); return 0; }
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 5291b86..dd3ebb4 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1249,11 +1249,6 @@ static void imx_disable_dma(struct imx_port *sport) imx_stop_rx_dma(sport); imx_stop_tx_dma(sport); - /* 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;