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

Peter Robinson
2018-03-08T10:06:12Z

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: GÃ¶ran 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
>