Re: [PATCH v3 1/2] libahci: Add support to handle HOST_IRQ_STAT as edge trigger latch.

[Tejun Heo <tj@kernel.org>]

On Sun, May 03, 2015 at 09:03:39PM +0530, Suman Tripathi wrote:
> This patch adds the support to handle HOST_IRQ_STAT as edge trigger
> latch.
...
> +	/*
> +	 * HOST_IRQ_STAT behaves as edge trigger latch. When HOST_IRQ_STAT
> +	 * detects a egde from PORT_IRQ_STAT, it happens to loose interrupts
> +	 * when interrupts are triggered from both ports. So handling of
> +	 * the residual interrupt is required.
> +	 */
> +	if (hpriv->flags & AHCI_HFLAG_EDGE_TRIG_IRQ) {
> +		for (i = 0; i < host->n_ports; i++) {
> +			struct ata_port *ap;
> +
> +			ap = host->ports[i];
> +			if (ap) {
> +				ahci_port_intr(ap);
> +				VPRINTK("Residual irq from port %u\n", i);
> +			}
> +			handled = 1;
> +		}
> +	}

This is kinda gross.  The right thing do is clearing irq stat
registers before handling the events, right?  That shouldn't be too
difficult to implement.  Create a separate set of irq functions which
clear irqs before processing rather than after.

Thanks.

-- 
tejun