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Date: Sat, 20 Apr 2019 12:06:26 +1000 From: Greg Ungerer <gerg@...inux.org> To: Arnd Bergmann <arnd@...db.de> Cc: Linus Walleij <linus.walleij@...aro.org>, arm@...nel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 5/6] ARM: ks8695, serial: skip manual tx IRQ ack 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@...db.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); >
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