* [PATCH] serial: a3720: Implement pending method for output direction
@ 2021-01-14 14:46 Pali Rohár
2021-01-15 14:50 ` Stefan Roese
0 siblings, 1 reply; 3+ messages in thread
From: Pali Rohár @ 2021-01-14 14:46 UTC (permalink / raw)
To: u-boot
To check if some output characters are waiting either in Transmitter
Holding Register or Transmitter Shift Register we need to look at
TX_EMPTY bit of UART Status Register.
Signed-off-by: Pali Roh?r <pali@kernel.org>
---
drivers/serial/serial_mvebu_a3700.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c
index fb43f88eaf..909901c9f0 100644
--- a/drivers/serial/serial_mvebu_a3700.c
+++ b/drivers/serial/serial_mvebu_a3700.c
@@ -23,6 +23,7 @@ struct mvebu_platdata {
#define UART_POSSR_REG 0x14
#define UART_STATUS_RX_RDY 0x10
+#define UART_STATUS_TX_EMPTY 0x40
#define UART_STATUS_TXFIFO_FULL 0x800
#define UART_CTRL_RXFIFO_RESET 0x4000
@@ -59,8 +60,13 @@ static int mvebu_serial_pending(struct udevice *dev, bool input)
struct mvebu_platdata *plat = dev_get_platdata(dev);
void __iomem *base = plat->base;
- if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
- return 1;
+ if (input) {
+ if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
+ return 1;
+ } else {
+ if (!(readl(base + UART_STATUS_REG) & UART_STATUS_TX_EMPTY))
+ return 1;
+ }
return 0;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH] serial: a3720: Implement pending method for output direction
2021-01-14 14:46 [PATCH] serial: a3720: Implement pending method for output direction Pali Rohár
@ 2021-01-15 14:50 ` Stefan Roese
2021-01-15 15:07 ` Pali Rohár
0 siblings, 1 reply; 3+ messages in thread
From: Stefan Roese @ 2021-01-15 14:50 UTC (permalink / raw)
To: u-boot
On 14.01.21 15:46, Pali Roh?r wrote:
> To check if some output characters are waiting either in Transmitter
> Holding Register or Transmitter Shift Register we need to look at
> TX_EMPTY bit of UART Status Register.
>
> Signed-off-by: Pali Roh?r <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
BTW: How did you detect this issue?
Thanks,
Stefan
> ---
> drivers/serial/serial_mvebu_a3700.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c
> index fb43f88eaf..909901c9f0 100644
> --- a/drivers/serial/serial_mvebu_a3700.c
> +++ b/drivers/serial/serial_mvebu_a3700.c
> @@ -23,6 +23,7 @@ struct mvebu_platdata {
> #define UART_POSSR_REG 0x14
>
> #define UART_STATUS_RX_RDY 0x10
> +#define UART_STATUS_TX_EMPTY 0x40
> #define UART_STATUS_TXFIFO_FULL 0x800
>
> #define UART_CTRL_RXFIFO_RESET 0x4000
> @@ -59,8 +60,13 @@ static int mvebu_serial_pending(struct udevice *dev, bool input)
> struct mvebu_platdata *plat = dev_get_platdata(dev);
> void __iomem *base = plat->base;
>
> - if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
> - return 1;
> + if (input) {
> + if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
> + return 1;
> + } else {
> + if (!(readl(base + UART_STATUS_REG) & UART_STATUS_TX_EMPTY))
> + return 1;
> + }
>
> return 0;
> }
>
Viele Gr??e,
Stefan
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr at denx.de
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH] serial: a3720: Implement pending method for output direction
2021-01-15 14:50 ` Stefan Roese
@ 2021-01-15 15:07 ` Pali Rohár
0 siblings, 0 replies; 3+ messages in thread
From: Pali Rohár @ 2021-01-15 15:07 UTC (permalink / raw)
To: u-boot
On Friday 15 January 2021 15:50:46 Stefan Roese wrote:
> On 14.01.21 15:46, Pali Roh?r wrote:
> > To check if some output characters are waiting either in Transmitter
> > Holding Register or Transmitter Shift Register we need to look at
> > TX_EMPTY bit of UART Status Register.
> >
> > Signed-off-by: Pali Roh?r <pali@kernel.org>
>
> Reviewed-by: Stefan Roese <sr@denx.de>
>
> BTW: How did you detect this issue?
During debugging both TF-A and linux kernel as they were eating
characters sent via A3720 UART. Details are in kernel and TF-A patches:
https://lore.kernel.org/linux-serial/20201223191931.18343-1-pali at kernel.org/
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/7734
I have not spotted this issue in U-Boot (only in TF-A and kernel), but I
decided to look also at the U-Boot A3720 UART implementation... And find
out that it is incomplete too, ignoring 'bool input' function argument.
> Thanks,
> Stefan
>
> > ---
> > drivers/serial/serial_mvebu_a3700.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c
> > index fb43f88eaf..909901c9f0 100644
> > --- a/drivers/serial/serial_mvebu_a3700.c
> > +++ b/drivers/serial/serial_mvebu_a3700.c
> > @@ -23,6 +23,7 @@ struct mvebu_platdata {
> > #define UART_POSSR_REG 0x14
> > #define UART_STATUS_RX_RDY 0x10
> > +#define UART_STATUS_TX_EMPTY 0x40
> > #define UART_STATUS_TXFIFO_FULL 0x800
> > #define UART_CTRL_RXFIFO_RESET 0x4000
> > @@ -59,8 +60,13 @@ static int mvebu_serial_pending(struct udevice *dev, bool input)
> > struct mvebu_platdata *plat = dev_get_platdata(dev);
> > void __iomem *base = plat->base;
> > - if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
> > - return 1;
> > + if (input) {
> > + if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
> > + return 1;
> > + } else {
> > + if (!(readl(base + UART_STATUS_REG) & UART_STATUS_TX_EMPTY))
> > + return 1;
> > + }
> > return 0;
> > }
> >
>
>
> Viele Gr??e,
> Stefan
>
> --
> DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: sr at denx.de
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-01-15 15:07 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-01-14 14:46 [PATCH] serial: a3720: Implement pending method for output direction Pali Rohár
2021-01-15 14:50 ` Stefan Roese
2021-01-15 15:07 ` Pali Rohár
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.