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

Tejun Heo
2015-05-04T15:47:26Z

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