[U-Boot] [PATCH v2 0/2] [for 2018.03] RPi: Drain RX queue on setbrg

[U-Boot] [PATCH v2 0/2] [for 2018.03] RPi: Drain RX queue on setbrg

[Alexander Graf]

We had a few reports coming in from people that had their autoboot chain
aborted after pinmuxing support was added for the RPi.

The culprit is easy: The UARTs may have been enabled before, but muxed
to an incorrect pin. That pin may have pulled the RX line down which again
lead to lots of zero bytes gathered in the RX buffer.

The easy fix for that is to drain the RX queue every time we set the baud
rate.

This patch set is the minimally intrusive fix for the RPi. We may want to
do that generically for all serial devices later.

v1 -> v2:

  - fix pl011 draining

Alexander Graf (2):
  serial_bcm283x_mu: Flush RX queue after setting baud rate
  bcm283x_pl011: Flush RX queue after setting baud rate

 drivers/serial/serial_bcm283x_mu.c     |  8 +++++++-
 drivers/serial/serial_bcm283x_pl011.c  | 25 ++++++++++++++++++++++++-
 drivers/serial/serial_pl01x.c          | 10 +++++-----
 drivers/serial/serial_pl01x_internal.h |  7 ++++++-
 4 files changed, 42 insertions(+), 8 deletions(-)

-- 
2.12.3

[U-Boot] [PATCH v2 1/2] serial_bcm283x_mu: Flush RX queue after setting baud rate

[Alexander Graf]

After the UART was initialized, we may still have bogus data in the
RX queue if it was enabled with incorrect pin muxing before.

So let's flush the RX queue whenever we initialize baud rates.

This fixes a regression with the dynamic pinmuxing code when enable_uart=1
is not set in config.txt.

Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
Reported-by: Göran Lundberg <goran@lundberg.email>
Reported-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 drivers/serial/serial_bcm283x_mu.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/serial/serial_bcm283x_mu.c b/drivers/serial/serial_bcm283x_mu.c
index 40029fadbc..d87b44e902 100644
--- a/drivers/serial/serial_bcm283x_mu.c
+++ b/drivers/serial/serial_bcm283x_mu.c
@@ -51,6 +51,8 @@ struct bcm283x_mu_priv {
 	struct bcm283x_mu_regs *regs;
 };
 
+static int bcm283x_mu_serial_getc(struct udevice *dev);
+
 static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
 {
 	struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
@@ -59,13 +61,17 @@ static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
 	u32 divider;
 
 	if (plat->skip_init)
-		return 0;
+		goto out;
 
 	divider = plat->clock / (baudrate * 8);
 
 	writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
 	writel(divider - 1, &regs->baud);
 
+out:
+	/* Flush the RX queue - all data in there is bogus */
+	while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ;
+
 	return 0;
 }
 
-- 
2.12.3

[U-Boot] [PATCH v2 1/2] serial_bcm283x_mu: Flush RX queue after setting baud rate

[Peter Robinson]

On Wed, Mar 7, 2018 at 9:08 PM, Alexander Graf <agraf@suse.de> wrote:
> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
>
> So let's flush the RX queue whenever we initialize baud rates.
>
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt.
>
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>

Tested-by: Peter Robinson <pbrobinson@gmail.com>

> ---
>  drivers/serial/serial_bcm283x_mu.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/serial/serial_bcm283x_mu.c b/drivers/serial/serial_bcm283x_mu.c
> index 40029fadbc..d87b44e902 100644
> --- a/drivers/serial/serial_bcm283x_mu.c
> +++ b/drivers/serial/serial_bcm283x_mu.c
> @@ -51,6 +51,8 @@ struct bcm283x_mu_priv {
>         struct bcm283x_mu_regs *regs;
>  };
>
> +static int bcm283x_mu_serial_getc(struct udevice *dev);
> +
>  static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
>  {
>         struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
> @@ -59,13 +61,17 @@ static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
>         u32 divider;
>
>         if (plat->skip_init)
> -               return 0;
> +               goto out;
>
>         divider = plat->clock / (baudrate * 8);
>
>         writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
>         writel(divider - 1, &regs->baud);
>
> +out:
> +       /* Flush the RX queue - all data in there is bogus */
> +       while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ;
> +
>         return 0;
>  }
>
> --
> 2.12.3
>

[U-Boot] [PATCH v2 1/2] serial_bcm283x_mu: Flush RX queue after setting baud rate

[Tuomas Tynkkynen]

On Wed, 7 Mar 2018 22:08:24 +0100
Alexander Graf <agraf@suse.de> wrote:

> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
> 
> So let's flush the RX queue whenever we initialize baud rates.
> 
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt.
> 
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
>  drivers/serial/serial_bcm283x_mu.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 

On a RPi 1, with no enable_uart in config.txt:

Tested-by: Tuomas Tynkkynen <tuomas@tuxera.com>

[U-Boot] [U-Boot, v2, 1/2] serial_bcm283x_mu: Flush RX queue after setting baud rate

[Tom Rini]

On Wed, Mar 07, 2018 at 10:08:24PM +0100, Alexander Graf wrote:

> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
> 
> So let's flush the RX queue whenever we initialize baud rates.
> 
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt.
> 
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> Tested-by: Peter Robinson <pbrobinson@gmail.com>
> Tested-by: Tuomas Tynkkynen <tuomas@tuxera.com>

Applied to u-boot/master, thanks!

-- 
Tom
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[U-Boot] [PATCH v2 2/2] bcm283x_pl011: Flush RX queue after setting baud rate

[Alexander Graf]

After the UART was initialized, we may still have bogus data in the
RX queue if it was enabled with incorrect pin muxing before.

So let's flush the RX queue whenever we initialize baud rates.

This fixes a regression with the dynamic pinmuxing code when enable_uart=1
is not set in config.txt on Raspberry Pis that use pl011 for serial.

Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
Reported-by: Göran Lundberg <goran@lundberg.email>
Reported-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

---

v1 -> v2:

  - correctly drain the queue
---
 drivers/serial/serial_bcm283x_pl011.c  | 25 ++++++++++++++++++++++++-
 drivers/serial/serial_pl01x.c          | 10 +++++-----
 drivers/serial/serial_pl01x_internal.h |  7 ++++++-
 3 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/drivers/serial/serial_bcm283x_pl011.c b/drivers/serial/serial_bcm283x_pl011.c
index bfd39f84f3..dad7236895 100644
--- a/drivers/serial/serial_bcm283x_pl011.c
+++ b/drivers/serial/serial_bcm283x_pl011.c
@@ -9,6 +9,7 @@
 #include <asm/gpio.h>
 #include <dm/pinctrl.h>
 #include <dm/platform_data/serial_pl01x.h>
+#include <serial.h>
 #include "serial_pl01x_internal.h"
 
 /*
@@ -55,6 +56,28 @@ static int bcm283x_pl011_serial_ofdata_to_platdata(struct udevice *dev)
 	return 0;
 }
 
+static int bcm283x_pl011_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	int r;
+
+	r = pl01x_serial_setbrg(dev, baudrate);
+
+	/*
+	 * We may have been muxed to a bogus line before. Drain the RX
+	 * queue so we start at a clean slate.
+	 */
+	while (pl01x_serial_getc(dev) != -EAGAIN) ;
+
+	return r;
+}
+
+static const struct dm_serial_ops bcm283x_pl011_serial_ops = {
+	.putc = pl01x_serial_putc,
+	.pending = pl01x_serial_pending,
+	.getc = pl01x_serial_getc,
+	.setbrg = bcm283x_pl011_serial_setbrg,
+};
+
 static const struct udevice_id bcm283x_pl011_serial_id[] = {
 	{.compatible = "brcm,bcm2835-pl011", .data = TYPE_PL011},
 	{}
@@ -67,7 +90,7 @@ U_BOOT_DRIVER(bcm283x_pl011_uart) = {
 	.ofdata_to_platdata = of_match_ptr(bcm283x_pl011_serial_ofdata_to_platdata),
 	.platdata_auto_alloc_size = sizeof(struct pl01x_serial_platdata),
 	.probe	= pl01x_serial_probe,
-	.ops	= &pl01x_serial_ops,
+	.ops	= &bcm283x_pl011_serial_ops,
 	.flags	= DM_FLAG_PRE_RELOC,
 	.priv_auto_alloc_size = sizeof(struct pl01x_priv),
 };
diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c
index 23d9d839cb..45f1282770 100644
--- a/drivers/serial/serial_pl01x.c
+++ b/drivers/serial/serial_pl01x.c
@@ -273,7 +273,7 @@ __weak struct serial_device *default_serial_console(void)
 
 #ifdef CONFIG_DM_SERIAL
 
-static int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
+int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
 {
 	struct pl01x_serial_platdata *plat = dev_get_platdata(dev);
 	struct pl01x_priv *priv = dev_get_priv(dev);
@@ -299,21 +299,21 @@ int pl01x_serial_probe(struct udevice *dev)
 		return 0;
 }
 
-static int pl01x_serial_getc(struct udevice *dev)
+int pl01x_serial_getc(struct udevice *dev)
 {
 	struct pl01x_priv *priv = dev_get_priv(dev);
 
 	return pl01x_getc(priv->regs);
 }
 
-static int pl01x_serial_putc(struct udevice *dev, const char ch)
+int pl01x_serial_putc(struct udevice *dev, const char ch)
 {
 	struct pl01x_priv *priv = dev_get_priv(dev);
 
 	return pl01x_putc(priv->regs, ch);
 }
 
-static int pl01x_serial_pending(struct udevice *dev, bool input)
+int pl01x_serial_pending(struct udevice *dev, bool input)
 {
 	struct pl01x_priv *priv = dev_get_priv(dev);
 	unsigned int fr = readl(&priv->regs->fr);
@@ -324,7 +324,7 @@ static int pl01x_serial_pending(struct udevice *dev, bool input)
 		return fr & UART_PL01x_FR_TXFF ? 0 : 1;
 }
 
-const struct dm_serial_ops pl01x_serial_ops = {
+static const struct dm_serial_ops pl01x_serial_ops = {
 	.putc = pl01x_serial_putc,
 	.pending = pl01x_serial_pending,
 	.getc = pl01x_serial_getc,
diff --git a/drivers/serial/serial_pl01x_internal.h b/drivers/serial/serial_pl01x_internal.h
index c56dd54c7b..d4605f24a3 100644
--- a/drivers/serial/serial_pl01x_internal.h
+++ b/drivers/serial/serial_pl01x_internal.h
@@ -43,7 +43,12 @@ struct pl01x_regs {
 
 int pl01x_serial_ofdata_to_platdata(struct udevice *dev);
 int pl01x_serial_probe(struct udevice *dev);
-extern const struct dm_serial_ops pl01x_serial_ops;
+
+/* Needed for external pl01x_serial_ops drivers */
+int pl01x_serial_putc(struct udevice *dev, const char ch);
+int pl01x_serial_pending(struct udevice *dev, bool input);
+int pl01x_serial_getc(struct udevice *dev);
+int pl01x_serial_setbrg(struct udevice *dev, int baudrate);
 
 struct pl01x_priv {
 	struct pl01x_regs *regs;
-- 
2.12.3

[U-Boot] [PATCH v2 2/2] bcm283x_pl011: Flush RX queue after setting baud rate

[Peter Robinson]

On Wed, Mar 7, 2018 at 9:08 PM, Alexander Graf <agraf@suse.de> wrote:
> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
>
> So let's flush the RX queue whenever we initialize baud rates.
>
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt on Raspberry Pis that use pl011 for serial.
>
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>
Tested-by: Peter Robinson <pbrobinson@gmail.com>

Tested on RPi2 and works a lot better, I can boot, interact with the
console etc :-)


> ---
>
> v1 -> v2:
>
>   - correctly drain the queue
> ---
>  drivers/serial/serial_bcm283x_pl011.c  | 25 ++++++++++++++++++++++++-
>  drivers/serial/serial_pl01x.c          | 10 +++++-----
>  drivers/serial/serial_pl01x_internal.h |  7 ++++++-
>  3 files changed, 35 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/serial/serial_bcm283x_pl011.c b/drivers/serial/serial_bcm283x_pl011.c
> index bfd39f84f3..dad7236895 100644
> --- a/drivers/serial/serial_bcm283x_pl011.c
> +++ b/drivers/serial/serial_bcm283x_pl011.c
> @@ -9,6 +9,7 @@
>  #include <asm/gpio.h>
>  #include <dm/pinctrl.h>
>  #include <dm/platform_data/serial_pl01x.h>
> +#include <serial.h>
>  #include "serial_pl01x_internal.h"
>
>  /*
> @@ -55,6 +56,28 @@ static int bcm283x_pl011_serial_ofdata_to_platdata(struct udevice *dev)
>         return 0;
>  }
>
> +static int bcm283x_pl011_serial_setbrg(struct udevice *dev, int baudrate)
> +{
> +       int r;
> +
> +       r = pl01x_serial_setbrg(dev, baudrate);
> +
> +       /*
> +        * We may have been muxed to a bogus line before. Drain the RX
> +        * queue so we start at a clean slate.
> +        */
> +       while (pl01x_serial_getc(dev) != -EAGAIN) ;
> +
> +       return r;
> +}
> +
> +static const struct dm_serial_ops bcm283x_pl011_serial_ops = {
> +       .putc = pl01x_serial_putc,
> +       .pending = pl01x_serial_pending,
> +       .getc = pl01x_serial_getc,
> +       .setbrg = bcm283x_pl011_serial_setbrg,
> +};
> +
>  static const struct udevice_id bcm283x_pl011_serial_id[] = {
>         {.compatible = "brcm,bcm2835-pl011", .data = TYPE_PL011},
>         {}
> @@ -67,7 +90,7 @@ U_BOOT_DRIVER(bcm283x_pl011_uart) = {
>         .ofdata_to_platdata = of_match_ptr(bcm283x_pl011_serial_ofdata_to_platdata),
>         .platdata_auto_alloc_size = sizeof(struct pl01x_serial_platdata),
>         .probe  = pl01x_serial_probe,
> -       .ops    = &pl01x_serial_ops,
> +       .ops    = &bcm283x_pl011_serial_ops,
>         .flags  = DM_FLAG_PRE_RELOC,
>         .priv_auto_alloc_size = sizeof(struct pl01x_priv),
>  };
> diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c
> index 23d9d839cb..45f1282770 100644
> --- a/drivers/serial/serial_pl01x.c
> +++ b/drivers/serial/serial_pl01x.c
> @@ -273,7 +273,7 @@ __weak struct serial_device *default_serial_console(void)
>
>  #ifdef CONFIG_DM_SERIAL
>
> -static int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
> +int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
>  {
>         struct pl01x_serial_platdata *plat = dev_get_platdata(dev);
>         struct pl01x_priv *priv = dev_get_priv(dev);
> @@ -299,21 +299,21 @@ int pl01x_serial_probe(struct udevice *dev)
>                 return 0;
>  }
>
> -static int pl01x_serial_getc(struct udevice *dev)
> +int pl01x_serial_getc(struct udevice *dev)
>  {
>         struct pl01x_priv *priv = dev_get_priv(dev);
>
>         return pl01x_getc(priv->regs);
>  }
>
> -static int pl01x_serial_putc(struct udevice *dev, const char ch)
> +int pl01x_serial_putc(struct udevice *dev, const char ch)
>  {
>         struct pl01x_priv *priv = dev_get_priv(dev);
>
>         return pl01x_putc(priv->regs, ch);
>  }
>
> -static int pl01x_serial_pending(struct udevice *dev, bool input)
> +int pl01x_serial_pending(struct udevice *dev, bool input)
>  {
>         struct pl01x_priv *priv = dev_get_priv(dev);
>         unsigned int fr = readl(&priv->regs->fr);
> @@ -324,7 +324,7 @@ static int pl01x_serial_pending(struct udevice *dev, bool input)
>                 return fr & UART_PL01x_FR_TXFF ? 0 : 1;
>  }
>
> -const struct dm_serial_ops pl01x_serial_ops = {
> +static const struct dm_serial_ops pl01x_serial_ops = {
>         .putc = pl01x_serial_putc,
>         .pending = pl01x_serial_pending,
>         .getc = pl01x_serial_getc,
> diff --git a/drivers/serial/serial_pl01x_internal.h b/drivers/serial/serial_pl01x_internal.h
> index c56dd54c7b..d4605f24a3 100644
> --- a/drivers/serial/serial_pl01x_internal.h
> +++ b/drivers/serial/serial_pl01x_internal.h
> @@ -43,7 +43,12 @@ struct pl01x_regs {
>
>  int pl01x_serial_ofdata_to_platdata(struct udevice *dev);
>  int pl01x_serial_probe(struct udevice *dev);
> -extern const struct dm_serial_ops pl01x_serial_ops;
> +
> +/* Needed for external pl01x_serial_ops drivers */
> +int pl01x_serial_putc(struct udevice *dev, const char ch);
> +int pl01x_serial_pending(struct udevice *dev, bool input);
> +int pl01x_serial_getc(struct udevice *dev);
> +int pl01x_serial_setbrg(struct udevice *dev, int baudrate);
>
>  struct pl01x_priv {
>         struct pl01x_regs *regs;
> --
> 2.12.3
>

[U-Boot] [PATCH v2 2/2] bcm283x_pl011: Flush RX queue after setting baud rate

[Tuomas Tynkkynen]

On Wed, 7 Mar 2018 22:08:25 +0100
Alexander Graf <agraf@suse.de> wrote:

> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
> 
> So let's flush the RX queue whenever we initialize baud rates.
> 
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt on Raspberry Pis that use pl011 for serial.
> 
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> 
> ---
> 
> v1 -> v2:
> 
>   - correctly drain the queue
> ---
>  drivers/serial/serial_bcm283x_pl011.c  | 25 ++++++++++++++++++++++++-
>  drivers/serial/serial_pl01x.c          | 10 +++++-----
>  drivers/serial/serial_pl01x_internal.h |  7 ++++++-
>  3 files changed, 35 insertions(+), 7 deletions(-)
> 

On a RPi 1, with no enable_uart in config.txt:

Tested-by: Tuomas Tynkkynen <tuomas@tuxera.com>

[U-Boot] [U-Boot, v2, 2/2] bcm283x_pl011: Flush RX queue after setting baud rate

[Tom Rini]

On Wed, Mar 07, 2018 at 10:08:25PM +0100, Alexander Graf wrote:

> After the UART was initialized, we may still have bogus data in the
> RX queue if it was enabled with incorrect pin muxing before.
> 
> So let's flush the RX queue whenever we initialize baud rates.
> 
> This fixes a regression with the dynamic pinmuxing code when enable_uart=1
> is not set in config.txt on Raspberry Pis that use pl011 for serial.
> 
> Fixes: caf2233b28 ("bcm283x: Add pinctrl driver")
> Reported-by: Göran Lundberg <goran@lundberg.email>
> Reported-by: Peter Robinson <pbrobinson@gmail.com>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> Tested-by: Peter Robinson <pbrobinson@gmail.com>
> Tested-by: Tuomas Tynkkynen <tuomas@tuxera.com>

Applied to u-boot/master, thanks!

-- 
Tom
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