Subject: [PATCH 1/7] ir-rx51: Handle signals properly

From: [email-masked] (Tony Lindgren)
Date: Tue, 20 Nov 2012 11:57:55 -0800

Hi,

* Timo Kokkonen <[email-masked]> [121118 07:15]:
> --- a/drivers/media/rc/ir-rx51.c
> +++ b/drivers/media/rc/ir-rx51.c
> @@ -74,6 +74,19 @@ static void lirc_rx51_off(struct lirc_rx51 *lirc_rx51)
>  			      OMAP_TIMER_TRIGGER_NONE);
>  }
>  
> +static void lirc_rx51_stop_tx(struct lirc_rx51 *lirc_rx51)
> +{
> +	if (lirc_rx51->wbuf_index < 0)
> +		return;
> +
> +	lirc_rx51_off(lirc_rx51);
> +	lirc_rx51->wbuf_index = -1;
> +	omap_dm_timer_stop(lirc_rx51->pwm_timer);
> +	omap_dm_timer_stop(lirc_rx51->pulse_timer);
> +	omap_dm_timer_set_int_enable(lirc_rx51->pulse_timer, 0);
> +	wake_up(&lirc_rx51->wqueue);
> +}
> +
>  static int init_timing_params(struct lirc_rx51 *lirc_rx51)
>  {
>  	u32 load, match;

Good fixes in general.. But you won't be able to access the
omap_dm_timer functions after we enable ARM multiplatform support
for omap2+. That's for v3.9 probably right after v3.8-rc1.

We need to find some Linux generic API to use hardware timers
like this, so I've added Thomas Gleixner and linux-arm-kernel
mailing list to cc.

If no such API is available, then maybe we can export some of
the omap_dm_timer functions if Thomas is OK with that.

The other alternative is to set them up as platform_data
function pointers, but that won't work after we make omap2+
device tree only. And that really just postpones the problem.

Cheers,

Tony

> @@ -163,13 +176,7 @@ static irqreturn_t lirc_rx51_interrupt_handler(int irq, void *ptr)
>  
>  	return IRQ_HANDLED;
>  end:
> -	/* Stop TX here */
> -	lirc_rx51_off(lirc_rx51);
> -	lirc_rx51->wbuf_index = -1;
> -	omap_dm_timer_stop(lirc_rx51->pwm_timer);
> -	omap_dm_timer_stop(lirc_rx51->pulse_timer);
> -	omap_dm_timer_set_int_enable(lirc_rx51->pulse_timer, 0);
> -	wake_up_interruptible(&lirc_rx51->wqueue);
> +	lirc_rx51_stop_tx(lirc_rx51);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -249,8 +256,9 @@ static ssize_t lirc_rx51_write(struct file *file, const char *buf,
>  	if ((count > WBUF_LEN) || (count % 2 == 0))
>  		return -EINVAL;
>  
> -	/* Wait any pending transfers to finish */
> -	wait_event_interruptible(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0);
> +	/* We can have only one transmit at a time */
> +	if (lirc_rx51->wbuf_index >= 0)
> +		return -EBUSY;
>  
>  	if (copy_from_user(lirc_rx51->wbuf, buf, n))
>  		return -EFAULT;
> @@ -276,9 +284,18 @@ static ssize_t lirc_rx51_write(struct file *file, const char *buf,
>  
>  	/*
>  	 * Don't return back to the userspace until the transfer has
> -	 * finished
> +	 * finished. However, we wish to not spend any more than 500ms
> +	 * in kernel. No IR code TX should ever take that long.
> +	 */
> +	i = wait_event_timeout(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0,
> +			HZ / 2);
> +
> +	/*
> +	 * Ensure transmitting has really stopped, even if the timers
> +	 * went mad or something else happened that caused it still
> +	 * sending out something.
>  	 */
> -	wait_event_interruptible(lirc_rx51->wqueue, lirc_rx51->wbuf_index < 0);
> +	lirc_rx51_stop_tx(lirc_rx51);
>  
>  	/* We can sleep again */
>  	lirc_rx51->pdata->set_max_mpu_wakeup_lat(lirc_rx51->dev, -1);
> -- 
> 1.8.0
> 
> --
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