[5/6] ARM: ks8695, serial: skip manual tx IRQ ack

Message ID 20190415202501.941196-5-arnd@arndb.de
State New
Headers show
Series
  • Untitled series #19864
Related show

Commit Message

Arnd Bergmann April 15, 2019, 8:24 p.m.
The TX interrupt is marked as edge triggered, so it will
already be acked by the top-level irq code, and does not
need the ack in the driver.

Removing this avoids a nasty dependency on the regs-irq.h
file that is otherwise reserved for the interrupt controller
driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/tty/serial/serial_ks8695.c | 5 -----
 1 file changed, 5 deletions(-)

-- 
2.20.0

Comments

Greg Ungerer April 20, 2019, 2:06 a.m. | #1
Hi Arnd,

On 16/4/19 6:24 am, Arnd Bergmann wrote:
> The TX interrupt is marked as edge triggered, so it will

> already be acked by the top-level irq code, and does not

> need the ack in the driver.

> 

> Removing this avoids a nasty dependency on the regs-irq.h

> file that is otherwise reserved for the interrupt controller

> driver.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>   drivers/tty/serial/serial_ks8695.c | 5 -----

>   1 file changed, 5 deletions(-)

> 

> diff --git a/drivers/tty/serial/serial_ks8695.c b/drivers/tty/serial/serial_ks8695.c

> index b461d791188c..6c5e9900e69d 100644

> --- a/drivers/tty/serial/serial_ks8695.c

> +++ b/drivers/tty/serial/serial_ks8695.c

> @@ -21,7 +21,6 @@

>   #include <asm/mach/irq.h>

>   

>   #include <mach/regs-uart.h>

> -#include <mach/regs-irq.h>

>   

>   #if defined(CONFIG_SERIAL_KS8695_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)

>   #define SUPPORT_SYSRQ

> @@ -52,8 +51,6 @@

>   #define UART_GET_BRDR(p)	__raw_readl((p)->membase + KS8695_URBD)

>   #define UART_PUT_BRDR(p, c)	__raw_writel((c), (p)->membase + KS8695_URBD)

>   

> -#define KS8695_CLR_TX_INT()	__raw_writel(1 << KS8695_IRQ_UART_TX, KS8695_IRQ_VA + KS8695_INTST)

> -

>   #define UART_DUMMY_LSR_RX	0x100

>   #define UART_PORT_SIZE		(KS8695_USR - KS8695_URRB + 4)

>   

> @@ -207,7 +204,6 @@ static irqreturn_t ks8695uart_tx_chars(int irq, void *dev_id)

>   	unsigned int count;

>   

>   	if (port->x_char) {

> -		KS8695_CLR_TX_INT();

>   		UART_PUT_CHAR(port, port->x_char);

>   		port->icount.tx++;

>   		port->x_char = 0;

> @@ -221,7 +217,6 @@ static irqreturn_t ks8695uart_tx_chars(int irq, void *dev_id)

>   

>   	count = 16;	/* fifo size */

>   	while (!uart_circ_empty(xmit) && (count-- > 0)) {

> -		KS8695_CLR_TX_INT();


I haven't looked at the ks8695 in quite a while...
But I recall that this was very problematic at the time. Without this being
done after each character it was very easy to get the transmitter to "hang" -
and stop wanting to send any more characters.

I'd like to test this before acking.

Regards
Greg


>   		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);

>   

>   		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);

>

Patch

diff --git a/drivers/tty/serial/serial_ks8695.c b/drivers/tty/serial/serial_ks8695.c
index b461d791188c..6c5e9900e69d 100644
--- a/drivers/tty/serial/serial_ks8695.c
+++ b/drivers/tty/serial/serial_ks8695.c
@@ -21,7 +21,6 @@ 
 #include <asm/mach/irq.h>
 
 #include <mach/regs-uart.h>
-#include <mach/regs-irq.h>
 
 #if defined(CONFIG_SERIAL_KS8695_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
 #define SUPPORT_SYSRQ
@@ -52,8 +51,6 @@ 
 #define UART_GET_BRDR(p)	__raw_readl((p)->membase + KS8695_URBD)
 #define UART_PUT_BRDR(p, c)	__raw_writel((c), (p)->membase + KS8695_URBD)
 
-#define KS8695_CLR_TX_INT()	__raw_writel(1 << KS8695_IRQ_UART_TX, KS8695_IRQ_VA + KS8695_INTST)
-
 #define UART_DUMMY_LSR_RX	0x100
 #define UART_PORT_SIZE		(KS8695_USR - KS8695_URRB + 4)
 
@@ -207,7 +204,6 @@  static irqreturn_t ks8695uart_tx_chars(int irq, void *dev_id)
 	unsigned int count;
 
 	if (port->x_char) {
-		KS8695_CLR_TX_INT();
 		UART_PUT_CHAR(port, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
@@ -221,7 +217,6 @@  static irqreturn_t ks8695uart_tx_chars(int irq, void *dev_id)
 
 	count = 16;	/* fifo size */
 	while (!uart_circ_empty(xmit) && (count-- > 0)) {
-		KS8695_CLR_TX_INT();
 		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
 
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);