From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
Subject: Re: [PATCH v2] ARM: OMAP: i2c: fix interrupt flood during resume
Date: Wed, 10 Oct 2012 14:54:11 +0300
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ke, 2012-10-10 kello 14:46 +0300, Kalle Jokiniemi kirjoitti:
> The resume_noirq enables interrupts one-by-one starting from
> first one. Now if the wake up event for suspend came from i2c
> device, the i2c bus irq gets enabled before the threaded
> i2c device irq, causing a flood of i2c bus interrupts as the
> threaded irq that should clear the event is not enabled yet.
> 
> Fixed the issue by adding suspend_late and resume_early
> functions that keep i2c bus interrupts disabled until
> resume_noirq has run completely.
> 
> Issue was detected doing a wake up from autosleep with
> twl4030 power key on N9. Patch tested on N9.

I did this now on top of latest linux-omap, should apply also to Jean's
staging tree. Let me know if something more is needed.

- Kalle

> 
> Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jollamobile.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |   34 ++++++++++++++++++++++++++++++++++
>  1 files changed, 34 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index a0e49f6..991341b 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -1132,6 +1132,36 @@ static int __devexit omap_i2c_remove(struct platform_device *pdev)
>  }
>  
>  #ifdef CONFIG_PM
> +#ifdef CONFIG_PM_SLEEP
> +static int omap_i2c_suspend_noirq(struct device *dev)
> +{
> +
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> +
> +	/* Disabling irq here to balance the enable in resume_early */
> +	disable_irq(_dev->irq);
> +	return 0;
> +}
> +
> +static int omap_i2c_resume_early(struct device *dev)
> +{
> +
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct omap_i2c_dev *_dev = platform_get_drvdata(pdev);
> +
> +	/*
> +	 * The noirq_resume enables the interrupts one by one,
> +	 * this causes a interrupt flood if the SW irq actually reading
> +	 * event from i2c device is enabled only after i2c bus irq, as the
> +	 * irq that should clear the event is still disabled. We have to
> +	 * keep the bus irq disabled until all other irqs have been enabled.
> +	 */
> +	enable_irq(_dev->irq);
> +
> +	return 0;
> +}
> +#endif
>  #ifdef CONFIG_PM_RUNTIME
>  static int omap_i2c_runtime_suspend(struct device *dev)
>  {
> @@ -1183,6 +1213,10 @@ static int omap_i2c_runtime_resume(struct device *dev)
>  #endif /* CONFIG_PM_RUNTIME */
>  
>  static struct dev_pm_ops omap_i2c_pm_ops = {
> +#ifdef CONFIG_PM_SLEEP
> +	.suspend_noirq = omap_i2c_suspend_noirq,
> +	.resume_early = omap_i2c_resume_early,
> +#endif
>  	SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
>  			   omap_i2c_runtime_resume, NULL)
>  };