Re: [PATCH #upstraem-fixes] ata_piix: detect and clear spurious IRQs

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Tejun Heo wrote:

> The DMA_IRQ bit in the bmdma status register is always set when IDEIRQ
> is asserted allowing spurious IRQ detection.  Detect spurious IRQs and
> clear them.  This protects ata_piix against nobody-cared which gets
> reported not so rarely.

    This should be more generic, as several IDE controllers have the separate 
IDE interrupt status bits.

> Signed-off-by: Tejun Heo <tj@kernel.org>

> diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
> index 8e37be1..b438edc 100644
> --- a/drivers/ata/ata_piix.c
> +++ b/drivers/ata/ata_piix.c
> @@ -922,6 +922,58 @@ static int piix_sidpr_scr_read(struct ata_link *link,
>  	return 0;
>  }
>  
> +static irqreturn_t piix_interrupt(int irq, void *dev_instance)
> +{
[...]
> +		/*
> +		 * Control reaches here if HSM is not expecting IRQ.
> +		 * If the controller is actually asserting IRQ line,
> +		 * this will lead to nobody cared.  Fortuantely,
> +		 * DMA_INTR of PIIX is set whenever IDEIRQ is set so

    Frankly speaking, I'm not sure about the PIIX chips themselves... Is that 
documented by Intel?

MBR, Sergei