* [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP @ 2017-06-20 15:37 Clemens Gruber 2017-06-20 16:13 ` Fabio Estevam 2017-06-23 9:26 ` AW: [Customers.Eckelmann] " Schenk, Gavin 0 siblings, 2 replies; 12+ messages in thread From: Clemens Gruber @ 2017-06-20 15:37 UTC (permalink / raw) To: linux-serial Cc: Greg Kroah-Hartman, Fabio Estevam, u.kleine-koenig, linux-kernel, Clemens Gruber, stable DMA support for half-duplex RS-485 never worked correctly on i.MX6Q/D due to an undiscovered SMP-related bug, instead of the real data being sent out, the rest of the transmit buffer is sent (xmit->tail jumps over xmit->head in imx_transmit_buffer and UART_XMIT_SIZE bytes are sent out) More details: https://lkml.org/lkml/2017/1/4/579 Disable it for that configuration until the bug is found and fixed. We need to know at probe time if we can enable DMA. (RS-485 could be enabled after that). Let's therefore only enable DMA if it is not an i.MX6Q/D UART with uart-has-rtscts in the DT and CONFIG_SMP enabled. Fixes: 17b8f2a3fdca ("serial: imx: add support for half duplex rs485") Cc: <stable@vger.kernel.org> Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com> --- drivers/tty/serial/imx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index bbefddd92bfe..000949f686a4 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1277,8 +1277,14 @@ static int imx_startup(struct uart_port *port) writel(temp & ~UCR4_DREN, sport->port.membase + UCR4); - /* Can we enable the DMA support? */ - if (!uart_console(port) && !sport->dma_is_inited) + /* + * Can we enable the DMA support? + * RS-485 DMA is broken on i.MX6D/Q SMP systems. Do not use DMA on + * UARTs with RTS/CTS to prevent misbehavior until the bug is fixed. + */ + if (!uart_console(port) && !sport->dma_is_inited && + !(sport->have_rtscts && is_imx6q_uart(sport) && + IS_ENABLED(CONFIG_SMP))) imx_uart_dma_init(sport); spin_lock_irqsave(&sport->port.lock, flags); -- 2.13.1 ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-20 15:37 [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP Clemens Gruber @ 2017-06-20 16:13 ` Fabio Estevam 2017-06-20 23:49 ` Fabio Estevam 2017-06-21 14:05 ` [PATCH] " Clemens Gruber 2017-06-23 9:26 ` AW: [Customers.Eckelmann] " Schenk, Gavin 1 sibling, 2 replies; 12+ messages in thread From: Fabio Estevam @ 2017-06-20 16:13 UTC (permalink / raw) To: Clemens Gruber Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, stable, Fugang Duan Hi Clemens, On Tue, Jun 20, 2017 at 12:37 PM, Clemens Gruber <clemens.gruber@pqgruber.com> wrote: > DMA support for half-duplex RS-485 never worked correctly on i.MX6Q/D > due to an undiscovered SMP-related bug, instead of the real data being > sent out, the rest of the transmit buffer is sent (xmit->tail jumps over > xmit->head in imx_transmit_buffer and UART_XMIT_SIZE bytes are sent out) > More details: https://lkml.org/lkml/2017/1/4/579 > > Disable it for that configuration until the bug is found and fixed. > > We need to know at probe time if we can enable DMA. (RS-485 could be > enabled after that). Let's therefore only enable DMA if it is not an > i.MX6Q/D UART with uart-has-rtscts in the DT and CONFIG_SMP enabled. > > Fixes: 17b8f2a3fdca ("serial: imx: add support for half duplex rs485") > Cc: <stable@vger.kernel.org> > Signed-off-by: Clemens Gruber <clemens.gruber@pqgruber.com> > --- > drivers/tty/serial/imx.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > index bbefddd92bfe..000949f686a4 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -1277,8 +1277,14 @@ static int imx_startup(struct uart_port *port) > > writel(temp & ~UCR4_DREN, sport->port.membase + UCR4); > > - /* Can we enable the DMA support? */ > - if (!uart_console(port) && !sport->dma_is_inited) > + /* > + * Can we enable the DMA support? > + * RS-485 DMA is broken on i.MX6D/Q SMP systems. Do not use DMA on > + * UARTs with RTS/CTS to prevent misbehavior until the bug is fixed. > + */ > + if (!uart_console(port) && !sport->dma_is_inited && > + !(sport->have_rtscts && is_imx6q_uart(sport) && > + IS_ENABLED(CONFIG_SMP))) > imx_uart_dma_init(sport); The subject gives the impression that the DMA will only be disabled for RS485, but the impact of this change is wider. For example: if I have a mx6q system with a Bluetooth serial connection I can no longer use DMA with your change applied. Ideally we should fix the RS485 DMA bug. If that is not possible, then at least we need to restrict this change to the RS485 case. Maybe we need to pass "linux,rs485-enabled-at-boot-time" in device tree and then use this property to deceide if DMA will be enabled or not: if (!uart_console(port) && !sport->dma_is_inited && !sport->rs485_enabled) ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-20 16:13 ` Fabio Estevam @ 2017-06-20 23:49 ` Fabio Estevam 2017-07-02 20:47 ` Clemens Gruber 2017-06-21 14:05 ` [PATCH] " Clemens Gruber 1 sibling, 1 reply; 12+ messages in thread From: Fabio Estevam @ 2017-06-20 23:49 UTC (permalink / raw) To: Clemens Gruber Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, stable, Fugang Duan [-- Attachment #1: Type: text/plain, Size: 944 bytes --] Hi Clemens, On Tue, Jun 20, 2017 at 1:13 PM, Fabio Estevam <festevam@gmail.com> wrote: > The subject gives the impression that the DMA will only be disabled > for RS485, but the impact of this change is wider. > > For example: if I have a mx6q system with a Bluetooth serial > connection I can no longer use DMA with your change applied. > > Ideally we should fix the RS485 DMA bug. If that is not possible, then > at least we need to restrict this change to the RS485 case. > > Maybe we need to pass "linux,rs485-enabled-at-boot-time" in device > tree and then use this property to deceide if DMA will be enabled or > not: > > if (!uart_console(port) && !sport->dma_is_inited && !sport->rs485_enabled) Could you please test the two attached patches and see if it solves the issue? Unfortunately I no longer have access to the RS485 half-duplex board. Just make sure to pass 'linux,rs485-enabled-at-boot-time' in your device tree, thanks. [-- Attachment #2: 0001-serial-imx-Allow-passing-linux-rs485-enabled-at-boot.patch --] [-- Type: text/x-patch, Size: 1172 bytes --] From 0a36d212228a8d093a03bbab94e9e6ffe99c87c3 Mon Sep 17 00:00:00 2001 From: Fabio Estevam <fabio.estevam@nxp.com> Date: Tue, 20 Jun 2017 20:29:13 -0300 Subject: [PATCH 1/2] serial: imx: Support 'linux,rs485-enabled-at-boot-time' According to Documentation/devicetree/bindings/serial/rs485.txt, the "linux,rs485-enabled-at-boot-time" property can be used to indicate that RS485 is enabled during boot time. Add support for it in the driver. Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com> --- drivers/tty/serial/imx.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 92606b1..90f8a5d 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -2123,6 +2123,9 @@ static int serial_imx_probe(struct platform_device *pdev) sport->port.rs485_config = imx_rs485_config; sport->port.rs485.flags = SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX; + if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL)) + sport->port.rs485.flags |= SER_RS485_ENABLED; + sport->port.flags = UPF_BOOT_AUTOCONF; init_timer(&sport->timer); sport->timer.function = imx_timeout; -- 2.7.4 [-- Attachment #3: 0002-serial-imx-Disable-DMA-for-RS485.patch --] [-- Type: text/x-patch, Size: 2240 bytes --] From bf63a07c546ceed3d2c3d203d75e87001144423f Mon Sep 17 00:00:00 2001 From: Fabio Estevam <fabio.estevam@nxp.com> Date: Tue, 20 Jun 2017 20:36:32 -0300 Subject: [PATCH 2/2] serial: imx: Disable DMA for RS485 Currently DMA support for half-duplex RS-485 does not work on i.MX6 as instead the real data being sent out, the rest of the transmit buffer is sent (xmit->tail jumps over xmit->head in imx_transmit_buffer and UART_XMIT_SIZE bytes are sent out). Disable DMA for the RS485 case until a proper fix is found. Reported-by: Clemens Gruber <clemens.gruber@pqgruber.com> Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com> --- drivers/tty/serial/imx.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 90f8a5d..4812e11 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -213,6 +213,7 @@ struct imx_port { struct clk *clk_ipg; struct clk *clk_per; const struct imx_uart_data *devdata; + bool rs485_enabled_at_boot; struct mctrl_gpios *gpios; @@ -1278,7 +1279,8 @@ static int imx_startup(struct uart_port *port) writel(temp & ~UCR4_DREN, sport->port.membase + UCR4); /* Can we enable the DMA support? */ - if (!uart_console(port) && !sport->dma_is_inited) + if (!uart_console(port) && !sport->dma_is_inited && + !sport->rs485_enabled_at_boot) imx_uart_dma_init(sport); spin_lock_irqsave(&sport->port.lock, flags); @@ -2087,6 +2089,7 @@ static void serial_imx_probe_pdata(struct imx_port *sport, static int serial_imx_probe(struct platform_device *pdev) { + struct device_node *np = pdev->dev.of_node; struct imx_port *sport; void __iomem *base; int ret = 0, reg; @@ -2123,8 +2126,10 @@ static int serial_imx_probe(struct platform_device *pdev) sport->port.rs485_config = imx_rs485_config; sport->port.rs485.flags = SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX; - if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL)) + if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL)) { sport->port.rs485.flags |= SER_RS485_ENABLED; + sport->rs485_enabled_at_boot = true; + } sport->port.flags = UPF_BOOT_AUTOCONF; init_timer(&sport->timer); -- 2.7.4 ^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-20 23:49 ` Fabio Estevam @ 2017-07-02 20:47 ` Clemens Gruber 2017-07-02 23:09 ` Fabio Estevam 0 siblings, 1 reply; 12+ messages in thread From: Clemens Gruber @ 2017-07-02 20:47 UTC (permalink / raw) To: Fabio Estevam Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, u.kleine-koenig, linux-kernel, Fugang Duan Hi Fabio, On Tue, Jun 20, 2017 at 08:49:28PM -0300, Fabio Estevam wrote: > Hi Clemens, > > On Tue, Jun 20, 2017 at 1:13 PM, Fabio Estevam <festevam@gmail.com> wrote: > > > The subject gives the impression that the DMA will only be disabled > > for RS485, but the impact of this change is wider. > > > > For example: if I have a mx6q system with a Bluetooth serial > > connection I can no longer use DMA with your change applied. > > > > Ideally we should fix the RS485 DMA bug. If that is not possible, then > > at least we need to restrict this change to the RS485 case. > > > > Maybe we need to pass "linux,rs485-enabled-at-boot-time" in device > > tree and then use this property to deceide if DMA will be enabled or > > not: > > > > if (!uart_console(port) && !sport->dma_is_inited && !sport->rs485_enabled) > > Could you please test the two attached patches and see if it solves the issue? > > Unfortunately I no longer have access to the RS485 half-duplex board. > > Just make sure to pass 'linux,rs485-enabled-at-boot-time' in your > device tree, thanks. The two patches work for me! You can add my Tested-by tag if/when you submit them. Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com> Regards, Clemens ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-07-02 20:47 ` Clemens Gruber @ 2017-07-02 23:09 ` Fabio Estevam 0 siblings, 0 replies; 12+ messages in thread From: Fabio Estevam @ 2017-07-02 23:09 UTC (permalink / raw) To: Clemens Gruber Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, Fugang Duan Hi Clemens, On Sun, Jul 2, 2017 at 5:47 PM, Clemens Gruber <clemens.gruber@pqgruber.com> wrote: > The two patches work for me! > > You can add my Tested-by tag if/when you submit them. > > Tested-by: Clemens Gruber <clemens.gruber@pqgruber.com> Thanks for testing. I will wait a bit longer to see if we can fix DMA usage with RS485. Regards, Fabio Estevam ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-20 16:13 ` Fabio Estevam 2017-06-20 23:49 ` Fabio Estevam @ 2017-06-21 14:05 ` Clemens Gruber 2017-06-21 14:12 ` Fabio Estevam 1 sibling, 1 reply; 12+ messages in thread From: Clemens Gruber @ 2017-06-21 14:05 UTC (permalink / raw) To: Fabio Estevam Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, Fugang Duan Hi Fabio, On Tue, Jun 20, 2017 at 01:13:18PM -0300, Fabio Estevam wrote: > The subject gives the impression that the DMA will only be disabled > for RS485, but the impact of this change is wider. > > For example: if I have a mx6q system with a Bluetooth serial > connection I can no longer use DMA with your change applied. > > Ideally we should fix the RS485 DMA bug. If that is not possible, then > at least we need to restrict this change to the RS485 case. > > Maybe we need to pass "linux,rs485-enabled-at-boot-time" in device > tree and then use this property to deceide if DMA will be enabled or > not: > > if (!uart_console(port) && !sport->dma_is_inited && !sport->rs485_enabled) I'd also prefer fixing the underlying problem. If you take a look at the DMA parts in drivers/tty/serial/imx.c, can you spot anything SMP-unsafe? By the way, can you get your hands on an i.MX6Q board with RS-485 to reproduce it? We could try for a few more weeks to find the bug and if we don't find it, adding this rs485-enabled-at-boot-time property sounds good! Thanks, Clemens ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-21 14:05 ` [PATCH] " Clemens Gruber @ 2017-06-21 14:12 ` Fabio Estevam 2017-06-30 12:15 ` Fabio Estevam 0 siblings, 1 reply; 12+ messages in thread From: Fabio Estevam @ 2017-06-21 14:12 UTC (permalink / raw) To: Clemens Gruber Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, Fugang Duan Hi Clemens, On Wed, Jun 21, 2017 at 11:05 AM, Clemens Gruber <clemens.gruber@pqgruber.com> wrote: > > I'd also prefer fixing the underlying problem. Yes, that would be much better. > If you take a look at the DMA parts in drivers/tty/serial/imx.c, can you > spot anything SMP-unsafe? Not really. > By the way, can you get your hands on an i.MX6Q board with RS-485 to > reproduce it? Unfortunately I don't have such hardware. Even the mx6solo board that I used to have access in the past I do not have it anymore. > We could try for a few more weeks to find the bug and if we don't find > it, adding this rs485-enabled-at-boot-time property sounds good! Sounds like a good plan, thanks. ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-21 14:12 ` Fabio Estevam @ 2017-06-30 12:15 ` Fabio Estevam 2017-07-02 20:17 ` Clemens Gruber 0 siblings, 1 reply; 12+ messages in thread From: Fabio Estevam @ 2017-06-30 12:15 UTC (permalink / raw) To: Clemens Gruber Cc: linux-serial, Greg Kroah-Hartman, Fabio Estevam, Uwe Kleine-König, linux-kernel, Fugang Duan, G.Schenk Hi Clemens, On Wed, Jun 21, 2017 at 11:12 AM, Fabio Estevam <festevam@gmail.com> wrote: >> I'd also prefer fixing the underlying problem. > > Yes, that would be much better. Just saw Romain's patch series that addresses several imx uart DMA issues: http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/516845.html If you have a chance, please give it a try to see if it helps on the RS485 DMA case. Regards, Fabio Estevam ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-30 12:15 ` Fabio Estevam @ 2017-07-02 20:17 ` Clemens Gruber 0 siblings, 0 replies; 12+ messages in thread From: Clemens Gruber @ 2017-07-02 20:17 UTC (permalink / raw) To: Fabio Estevam, Romain Perier Cc: linux-serial, Nandor Han, Greg Kroah-Hartman, linux-arm-kernel, linux-kernel, u.kleine-koenig, Fugang Duan, G.Schenk Hi Fabio, Hi Romain, On Fri, Jun 30, 2017 at 09:15:31AM -0300, Fabio Estevam wrote: > Hi Clemens, > > On Wed, Jun 21, 2017 at 11:12 AM, Fabio Estevam <festevam@gmail.com> wrote: > > >> I'd also prefer fixing the underlying problem. > > > > Yes, that would be much better. > > Just saw Romain's patch series that addresses several imx uart DMA issues: > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/516845.html > > If you have a chance, please give it a try to see if it helps on the > RS485 DMA case. Thanks, I just finished my first tests with Romain's patch series: It looks like these patches fixed some of the bugs, causing this behavior, but not all: The behavior changed, the rest of the circular buffer is no longer sent out as seen in the previous bug report (https://pqgruber.com/rs485_results.png) But now, with the patch series applied, if I transmit "Test", the logic analyzer records the following: https://pqgruber.com/rs485txtest.png Most of the time it looked like this (T e T e s s t t LF LF), but in a few cases I observed another pattern (T e T s e s t t LF LF) when transmitting "Test" by calling echo Test > /dev/ttymxc4. If I do a echo A > /dev/ttymxc4 as in my first bug report, now I always see the pattern A LF A LF on the TX line, but no longer A LF A LF 0 0 .. Interestingly, the bug does not appear the first time I try echo A after a reboot. Romain: What board did you use to test your patch series? The RS485 bug, I reported, only appears on i.MX6D and i.MX6Q, but not on single-core / non-SMP systems. Would be great if you could reproduce it! Regards, Clemens ^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP @ 2017-07-02 20:17 ` Clemens Gruber 0 siblings, 0 replies; 12+ messages in thread From: Clemens Gruber @ 2017-07-02 20:17 UTC (permalink / raw) To: linux-arm-kernel Hi Fabio, Hi Romain, On Fri, Jun 30, 2017 at 09:15:31AM -0300, Fabio Estevam wrote: > Hi Clemens, > > On Wed, Jun 21, 2017 at 11:12 AM, Fabio Estevam <festevam@gmail.com> wrote: > > >> I'd also prefer fixing the underlying problem. > > > > Yes, that would be much better. > > Just saw Romain's patch series that addresses several imx uart DMA issues: > http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/516845.html > > If you have a chance, please give it a try to see if it helps on the > RS485 DMA case. Thanks, I just finished my first tests with Romain's patch series: It looks like these patches fixed some of the bugs, causing this behavior, but not all: The behavior changed, the rest of the circular buffer is no longer sent out as seen in the previous bug report (https://pqgruber.com/rs485_results.png) But now, with the patch series applied, if I transmit "Test", the logic analyzer records the following: https://pqgruber.com/rs485txtest.png Most of the time it looked like this (T e T e s s t t LF LF), but in a few cases I observed another pattern (T e T s e s t t LF LF) when transmitting "Test" by calling echo Test > /dev/ttymxc4. If I do a echo A > /dev/ttymxc4 as in my first bug report, now I always see the pattern A LF A LF on the TX line, but no longer A LF A LF 0 0 .. Interestingly, the bug does not appear the first time I try echo A after a reboot. Romain: What board did you use to test your patch series? The RS485 bug, I reported, only appears on i.MX6D and i.MX6Q, but not on single-core / non-SMP systems. Would be great if you could reproduce it! Regards, Clemens ^ permalink raw reply [flat|nested] 12+ messages in thread
* AW: [Customers.Eckelmann] [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-20 15:37 [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP Clemens Gruber 2017-06-20 16:13 ` Fabio Estevam @ 2017-06-23 9:26 ` Schenk, Gavin 2017-07-17 11:34 ` Fabio Estevam 1 sibling, 1 reply; 12+ messages in thread From: Schenk, Gavin @ 2017-06-23 9:26 UTC (permalink / raw) To: Clemens Gruber, linux-serial Cc: Greg Kroah-Hartman, linux-kernel, stable, u.kleine-koenig, Fabio Estevam Hi, > > DMA support for half-duplex RS-485 never worked correctly on i.MX6Q/D > due to an undiscovered SMP-related bug, instead of the real data being > sent out, the rest of the transmit buffer is sent (xmit->tail jumps over > xmit->head in imx_transmit_buffer and UART_XMIT_SIZE bytes are sent out) > More details: https://lkml.org/lkml/2017/1/4/579 > We see exactly this issue on our platform, based on i.MX6dl. We use the RS485 mode to implement a Modbus interface. We have another platform based on i.MX25 running the same Linux 4.9.30 code that is not affected! > Disable it for that configuration until the bug is found and fixed. > > We need to know at probe time if we can enable DMA. (RS-485 could be > enabled after that). Let's therefore only enable DMA if it is not an > i.MX6Q/D UART with uart-has-rtscts in the DT and CONFIG_SMP enabled. > Uwe Kleine-König had the idea to disable DMA on the i.MX6dl based platform via dts and this is our current workaround. Regards Gavin Schenk Eckelmann AG Vorstand: Dipl.-Ing. Peter Frankenbach (Sprecher) Dipl.-Wi.-Ing. Philipp Eckelmann Dr.-Ing. Marco Münchhof Dr.-Ing. Frank Uhlemann Vorsitzender des Aufsichtsrats: Hubertus G. Krossa Stv. Vorsitzender des Aufsichtsrats: Dr.-Ing. Gerd Eckelmann Sitz der Gesellschaft: Berliner Str. 161, 65205 Wiesbaden, Amtsgericht Wiesbaden HRB 12636 http://www.eckelmann.de ^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [Customers.Eckelmann] [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP 2017-06-23 9:26 ` AW: [Customers.Eckelmann] " Schenk, Gavin @ 2017-07-17 11:34 ` Fabio Estevam 0 siblings, 0 replies; 12+ messages in thread From: Fabio Estevam @ 2017-07-17 11:34 UTC (permalink / raw) To: Schenk, Gavin Cc: Clemens Gruber, linux-serial, Greg Kroah-Hartman, linux-kernel, stable, u.kleine-koenig, Fabio Estevam, Ian Jamison Hi Gavin, On Fri, Jun 23, 2017 at 6:26 AM, Schenk, Gavin <G.Schenk@eckelmann.de> wrote: > Uwe Kleine-König had the idea to disable DMA on the i.MX6dl based platform via dts and this is our current workaround. Please test Ian's patch: http://marc.info/?l=linux-serial&m=150005865213531&w=2 It should fix this DMA problem with RS485. ^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2017-07-17 11:35 UTC | newest] Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2017-06-20 15:37 [PATCH] serial: imx: disable DMA for RS-485 on i.MX6 SMP Clemens Gruber 2017-06-20 16:13 ` Fabio Estevam 2017-06-20 23:49 ` Fabio Estevam 2017-07-02 20:47 ` Clemens Gruber 2017-07-02 23:09 ` Fabio Estevam 2017-06-21 14:05 ` [PATCH] " Clemens Gruber 2017-06-21 14:12 ` Fabio Estevam 2017-06-30 12:15 ` Fabio Estevam 2017-07-02 20:17 ` Clemens Gruber 2017-07-02 20:17 ` Clemens Gruber 2017-06-23 9:26 ` AW: [Customers.Eckelmann] " Schenk, Gavin 2017-07-17 11:34 ` Fabio Estevam
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.