linux-kernel - Re: [PATCH] serial: omap: Fix IRQ handling return value

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Message-ID: <CAGa+x84dE_RwN2G1y_9OJFxnq3JKq5g0YZd+mFueOjjvMzyyew@mail.gmail.com>
Date:	Tue, 20 Aug 2013 08:44:50 -0700
From:	Kevin Hilman <khilman@...aro.org>
To:	Alexander Savchenko <oleksandr.savchenko@...com>
Cc:	gregkh@...uxfoundation.org, jslaby@...e.cz,
	linux-serial@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Ruchika Kharwar <ruchika@...com>, balbi@...com
Subject: Re: [PATCH] serial: omap: Fix IRQ handling return value

+Felipe

On Wed, Jul 17, 2013 at 6:29 AM, Alexander Savchenko
<oleksandr.savchenko@...com> wrote:
> From: Ruchika Kharwar <ruchika@...com>
>
> Ensure the Interrupt handling routine return IRQ_HANDLED vs
> IRQ_NONE.

Why?

By unconditionally returning IRQ_HANDLED, this patch will surely break
systems where the UART IRQ is shared with other platforms.

I just noticed this patch when bisecting a related problem.  Why
wasn't this Cc'd to linux-omap where OMAP users might have been more
likely to see it?

Greg, without a better justification in the changelog, I think this
patch should be dropped from tty-next.

Kevin

> Signed-off-by: Ruchika Kharwar <ruchika@...com>
> Signed-off-by: Alexander Savchenko <oleksandr.savchenko@...com>
> ---
>  drivers/tty/serial/omap-serial.c |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index b6d1728..70feeb3 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -479,7 +479,6 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id)
>         struct uart_omap_port *up = dev_id;
>         unsigned int iir, lsr;
>         unsigned int type;
> -       irqreturn_t ret = IRQ_NONE;
>         int max_count = 256;
>
>         spin_lock(&up->port.lock);
> @@ -490,7 +489,6 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id)
>                 if (iir & UART_IIR_NO_INT)
>                         break;
>
> -               ret = IRQ_HANDLED;
>                 lsr = serial_in(up, UART_LSR);
>
>                 /* extract IRQ type from IIR register */
> @@ -529,7 +527,7 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id)
>         pm_runtime_put_autosuspend(up->dev);
>         up->port_activity = jiffies;
>
> -       return ret;
> +       return IRQ_HANDLED;
>  }
>
>  static unsigned int serial_omap_tx_empty(struct uart_port *port)
> --
> 1.7.9.5
>
> --
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