Re: SATA exceptions with 2.6.20-rc5

[Robert Hancock <hancockr@shaw.ca>]

Björn Steinbrink wrote:
> Hm, I don't think it is unhappy about looking at NV_INT_STATUS_CK804.
> I'm running 2.6.20-rc5 with the INT_DEV check removed for 8 hours now
> without a single problem and that should still look at
> NV_INT_STATUS_CK804, right?
> I just noticed that my last email might not have been clear enough. The
> exceptions happened when I re-enabled the return statement in addition
> to the debug message. Without the INT_DEV check, it is completely fine
> AFAICT.

Indeed, it seems to be just the NV_INT_DEV check that is problematic. 
Here's a patch that's likely better to test, it forces the NV_INT_DEV 
flag on when a command is active, and also fixes that questionable code 
in nv_host_intr that I mentioned.

--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

--- linux-2.6.20-rc5/drivers/ata/sata_nv.c	2007-01-19 19:18:53.000000000 -0600
+++ linux-2.6.20-rc5debug/drivers/ata/sata_nv.c	2007-01-22 22:33:43.000000000 -0600
@@ -700,7 +700,6 @@ static void nv_adma_check_cpb(struct ata
 static int nv_host_intr(struct ata_port *ap, u8 irq_stat)
 {
 	struct ata_queued_cmd *qc = ata_qc_from_tag(ap, ap->active_tag);
-	int handled;
 
 	/* freeze if hotplugged */
 	if (unlikely(irq_stat & (NV_INT_ADDED | NV_INT_REMOVED))) {
@@ -719,13 +718,7 @@ static int nv_host_intr(struct ata_port 
 	}
 
 	/* handle interrupt */
-	handled = ata_host_intr(ap, qc);
-	if (unlikely(!handled)) {
-		/* spurious, clear it */
-		ata_check_status(ap);
-	}
-
-	return 1;
+	return ata_host_intr(ap, qc);
 }
 
 static irqreturn_t nv_adma_interrupt(int irq, void *dev_instance)
@@ -752,6 +745,11 @@ static irqreturn_t nv_adma_interrupt(int
 			if (pp->flags & NV_ADMA_PORT_REGISTER_MODE) {
 				u8 irq_stat = readb(host->mmio_base + NV_INT_STATUS_CK804)
 					>> (NV_INT_PORT_SHIFT * i);
+				if(ata_tag_valid(ap->active_tag))
+					/** NV_INT_DEV indication seems unreliable at times
+					    at least in ADMA mode. Force it on always when a
+					    command is active, to prevent losing interrupts. */
+					irq_stat |= NV_INT_DEV;
 				handled += nv_host_intr(ap, irq_stat);
 				continue;
 			}