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Message-ID: <CAHp75Vc+t9_FNHZ0xYNaJ1+Ny+FFeZKA79abxV2NAsZvpBh3Bg@mail.gmail.com>
Date: Fri, 5 Mar 2021 17:17:54 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Hector Martin <marcan@...can.st>
Cc: linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
Marc Zyngier <maz@...nel.org>, Rob Herring <robh@...nel.org>,
Arnd Bergmann <arnd@...nel.org>,
Olof Johansson <olof@...om.net>,
Krzysztof Kozlowski <krzk@...nel.org>,
Mark Kettenis <mark.kettenis@...all.nl>,
Tony Lindgren <tony@...mide.com>,
Mohamed Mediouni <mohamed.mediouni@...amail.com>,
Stan Skowronek <stan@...ellium.com>,
Alexander Graf <graf@...zon.com>,
Will Deacon <will@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Mark Rutland <mark.rutland@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jonathan Corbet <corbet@....net>,
Catalin Marinas <catalin.marinas@....com>,
Christoph Hellwig <hch@...radead.org>,
"David S. Miller" <davem@...emloft.net>,
devicetree <devicetree@...r.kernel.org>,
"open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
Linux Documentation List <linux-doc@...r.kernel.org>,
Linux Samsung SOC <linux-samsung-soc@...r.kernel.org>,
Linux-Arch <linux-arch@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFT PATCH v3 21/27] tty: serial: samsung_tty: IRQ rework
On Thu, Mar 4, 2021 at 11:41 PM Hector Martin <marcan@...can.st> wrote:
>
> * Split out s3c24xx_serial_tx_chars from s3c24xx_serial_tx_irq,
> where only the latter acquires the port lock. This will be necessary
> on platforms which have edge-triggered IRQs, as we need to call
> s3c24xx_serial_tx_chars to kick off transmission from outside IRQ
> context, with the port lock held.
>
> * Rename s3c24xx_serial_rx_chars to s3c24xx_serial_rx_irq for
> consistency with the above. All it does now is call two other
> functions anyway.
>
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
> drivers/tty/serial/samsung_tty.c | 34 +++++++++++++++++++-------------
> 1 file changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> index 39b2eb165bdc..7106eb238d8c 100644
> --- a/drivers/tty/serial/samsung_tty.c
> +++ b/drivers/tty/serial/samsung_tty.c
> @@ -827,7 +827,7 @@ static irqreturn_t s3c24xx_serial_rx_chars_pio(void *dev_id)
> return IRQ_HANDLED;
> }
>
> -static irqreturn_t s3c24xx_serial_rx_chars(int irq, void *dev_id)
> +static irqreturn_t s3c24xx_serial_rx_irq(int irq, void *dev_id)
> {
> struct s3c24xx_uart_port *ourport = dev_id;
>
> @@ -836,16 +836,12 @@ static irqreturn_t s3c24xx_serial_rx_chars(int irq, void *dev_id)
> return s3c24xx_serial_rx_chars_pio(dev_id);
> }
>
> -static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
> +static void s3c24xx_serial_tx_chars(struct s3c24xx_uart_port *ourport)
> {
> - struct s3c24xx_uart_port *ourport = id;
> struct uart_port *port = &ourport->port;
> struct circ_buf *xmit = &port->state->xmit;
> - unsigned long flags;
> int count, dma_count = 0;
>
> - spin_lock_irqsave(&port->lock, flags);
> -
> count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
>
> if (ourport->dma && ourport->dma->tx_chan &&
> @@ -862,7 +858,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
> wr_reg(port, S3C2410_UTXH, port->x_char);
> port->icount.tx++;
> port->x_char = 0;
> - goto out;
> + return;
> }
>
> /* if there isn't anything more to transmit, or the uart is now
> @@ -871,7 +867,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
>
> if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
> s3c24xx_serial_stop_tx(port);
> - goto out;
> + return;
> }
>
> /* try and drain the buffer... */
> @@ -893,7 +889,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
>
> if (!count && dma_count) {
> s3c24xx_serial_start_tx_dma(ourport, dma_count);
> - goto out;
> + return;
> }
>
> if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) {
> @@ -904,8 +900,18 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
>
> if (uart_circ_empty(xmit))
> s3c24xx_serial_stop_tx(port);
> +}
> +
> +static irqreturn_t s3c24xx_serial_tx_irq(int irq, void *id)
> +{
> + struct s3c24xx_uart_port *ourport = id;
> + struct uart_port *port = &ourport->port;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + s3c24xx_serial_tx_chars(ourport);
>
> -out:
> spin_unlock_irqrestore(&port->lock, flags);
Add a separate change that removes flags from the spin lock in the IRQ handler.
> return IRQ_HANDLED;
> }
> @@ -919,11 +925,11 @@ static irqreturn_t s3c64xx_serial_handle_irq(int irq, void *id)
> irqreturn_t ret = IRQ_HANDLED;
>
> if (pend & S3C64XX_UINTM_RXD_MSK) {
> - ret = s3c24xx_serial_rx_chars(irq, id);
> + ret = s3c24xx_serial_rx_irq(irq, id);
> wr_regl(port, S3C64XX_UINTP, S3C64XX_UINTM_RXD_MSK);
> }
> if (pend & S3C64XX_UINTM_TXD_MSK) {
> - ret = s3c24xx_serial_tx_chars(irq, id);
> + ret = s3c24xx_serial_tx_irq(irq, id);
> wr_regl(port, S3C64XX_UINTP, S3C64XX_UINTM_TXD_MSK);
> }
> return ret;
> @@ -1155,7 +1161,7 @@ static int s3c24xx_serial_startup(struct uart_port *port)
>
> ourport->rx_enabled = 1;
>
> - ret = request_irq(ourport->rx_irq, s3c24xx_serial_rx_chars, 0,
> + ret = request_irq(ourport->rx_irq, s3c24xx_serial_rx_irq, 0,
> s3c24xx_serial_portname(port), ourport);
>
> if (ret != 0) {
> @@ -1169,7 +1175,7 @@ static int s3c24xx_serial_startup(struct uart_port *port)
>
> ourport->tx_enabled = 1;
>
> - ret = request_irq(ourport->tx_irq, s3c24xx_serial_tx_chars, 0,
> + ret = request_irq(ourport->tx_irq, s3c24xx_serial_tx_irq, 0,
> s3c24xx_serial_portname(port), ourport);
>
> if (ret) {
> --
> 2.30.0
>
--
With Best Regards,
Andy Shevchenko
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