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

Suman Tripathi
2015-05-04T16:43:11Z

On Mon, May 4, 2015 at 9:17 PM, Tejun Heo <tj@kernel.org> wrote:
> 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.

AFAIK clearing host_irq_stat means we have handled port interrupts .
Now for our case we still have interrupts left because it didn't get
detected on
first ahci_port_intr. So you mean to handle that residual irq in the
next cycle (i mean next call intr handler ) ??

>
> Thanks.
>
> --
> tejun

--
Thanks,
with regards,
Suman Tripathi