[PATCH] serial: a3720: Implement pending method for output direction
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 Rohár 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; }
On 14.01.21 15:46, Pali Rohár 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 Rohár 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 Grüße, Stefan
On Friday 15 January 2021 15:50:46 Stefan Roese wrote:
On 14.01.21 15:46, Pali Rohár 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 Rohár 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@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 Grüße, Stefan
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participants (2)
-
Pali Rohár -
Stefan Roese