[PATCH v4 0/2] serial: uartps: Add TACTIVE check

[PATCH v4 0/2] serial: uartps: Add TACTIVE check

[Shubhrajyoti Datta]

The cdns_uart_tx_empty function is currently checking oly for tx_empty
bit of SR. In some environments, it is leading to a corruption in log
because tx_empty does not gaurantee that all the bytes are transmitted
out of the FIFO. So, add TACTIVE bit in the check.

This patch series does the following:
-Remove unconditional wait for tx_empty inside set_termios function
-Add TACTIVE check in cdns_uart_tx_empty function

Changes in v4:
-Split into two patches as suggested by Johan

Raviteja Narayanam (2):
  serial: uartps: Remove unconditional wait inside set_termios
  serial: uartps: Add TACTIVE check in cdns_uart_tx_empty function

 drivers/tty/serial/xilinx_uartps.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

-- 
2.1.1

[PATCH v4 1/2] serial: uartps: Remove unconditional wait inside set_termios

[Shubhrajyoti Datta]

From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>

set_termios function should not wait for the transmit FIFO empty
(CDNS_UART_SR_TXEMPTY) unconditionally. The tty layer takes care
of it based on the parameter passed (TCSANOW/TCSADRAIN/TCSAFLUSH).

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 30a1425..662b8ab 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -706,20 +706,8 @@ static void cdns_uart_set_termios(struct uart_port *port,
 	u32 cval = 0;
 	unsigned int baud, minbaud, maxbaud;
 	unsigned long flags;
-	unsigned int ctrl_reg, mode_reg, val;
-	int err;
-
-	/* Wait for the transmit FIFO to empty before making changes */
-	if (!(readl(port->membase + CDNS_UART_CR) &
-				CDNS_UART_CR_TX_DIS)) {
-		err = readl_poll_timeout(port->membase + CDNS_UART_SR,
-					 val, (val & CDNS_UART_SR_TXEMPTY),
-					 1000, TX_TIMEOUT);
-		if (err) {
-			dev_err(port->dev, "timed out waiting for tx empty");
-			return;
-		}
-	}
+	unsigned int ctrl_reg, mode_reg;
+
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Disable the TX and RX to set baud rate */
-- 
2.1.1

[PATCH v4 2/2] serial: uartps: Add TACTIVE check in cdns_uart_tx_empty function

[Shubhrajyoti Datta]

From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>

Make sure that all bytes are transmitted out of Uart by monitoring
CDNS_UART_SR_TACTIVE bit as well.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 662b8ab..38cb76a9 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -663,8 +663,8 @@ static unsigned int cdns_uart_tx_empty(struct uart_port *port)
 	unsigned int status;
 
 	status = readl(port->membase + CDNS_UART_SR) &
-				CDNS_UART_SR_TXEMPTY;
-	return status ? TIOCSER_TEMT : 0;
+		       (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE);
+	return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0;
 }
 
 /**
-- 
2.1.1

Re: [PATCH v4 2/2] serial: uartps: Add TACTIVE check in cdns_uart_tx_empty function

[Maarten Brock]

On 2020-03-19 10:44, Shubhrajyoti Datta wrote:
> From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
> 
> Make sure that all bytes are transmitted out of Uart by monitoring
> CDNS_UART_SR_TACTIVE bit as well.
> 
> Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
> ---
>  drivers/tty/serial/xilinx_uartps.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/xilinx_uartps.c
> b/drivers/tty/serial/xilinx_uartps.c
> index 662b8ab..38cb76a9 100644
> --- a/drivers/tty/serial/xilinx_uartps.c
> +++ b/drivers/tty/serial/xilinx_uartps.c
> @@ -663,8 +663,8 @@ static unsigned int cdns_uart_tx_empty(struct
> uart_port *port)
>  	unsigned int status;
> 
>  	status = readl(port->membase + CDNS_UART_SR) &
> -				CDNS_UART_SR_TXEMPTY;
> -	return status ? TIOCSER_TEMT : 0;
> +		       (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE);
> +	return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0;
>  }
> 
>  /**

Acked-by: Maarten Brock <m.brock@vanmierlo.com>