Re: [smartmontools-support] inactive SATA drives won't stay in standbyor sleep, PATA models did. (fwd)

From: Mikael Pettersson
Date: Sun Oct 19 2008 - 19:41:01 EST

On Mon, 13 Oct 2008 14:16:24 +0900, Tejun Heo wrote:
>Mikael Pettersson wrote:
>> - hardreset in sata_promise seems broken. I'll take a closer look
>> at that in about a week's time (I'll be busy with other work the
>> next couple of days).
>This looks like a rather serious problem, so please take a look at

I've done more tests now, and the problem is that errors detected
outside of sata_promise itself, typically timeouts, don't trigger
the pdc_reset_port() call needed to bring the ATA engine behind the
port back to sanity.

And the reason no Promise-specific reset is done on timeouts is
that libata-eh freezes the port before calling ->error_handler.
sata_promise's error_handler only does a reset if the port is
non-frozen, and I think that's because we don't want to destroy
error status bits needed by EH autopsy.

The solution I've been testing is the straightforward one of
overriding ->prereset with code which calls pdc_reset_port()
before calling the default prereset. (See patch below.)
(Promise's own driver issues resets whenever there's a sign
of a problem.)

One of my test disks will often trigger a timeout if smartctl
accesses it when it's spun down. Previously the port would not
recover from that, but now it's just a brief reset/detect and
then it's up again.


--- linux-2.6.27/drivers/ata/sata_promise.c.~1~ 2008-07-14 10:22:36.000000000 +0200
+++ linux-2.6.27/drivers/ata/sata_promise.c 2008-10-20 00:20:58.000000000 +0200
@@ -153,6 +153,7 @@ static void pdc_freeze(struct ata_port *
static void pdc_sata_freeze(struct ata_port *ap);
static void pdc_thaw(struct ata_port *ap);
static void pdc_sata_thaw(struct ata_port *ap);
+static int pdc_prereset(struct ata_link *link, unsigned long deadline);
static void pdc_error_handler(struct ata_port *ap);
static void pdc_post_internal_cmd(struct ata_queued_cmd *qc);
static int pdc_pata_cable_detect(struct ata_port *ap);
@@ -175,6 +176,7 @@ static const struct ata_port_operations
.sff_irq_clear = pdc_irq_clear,

.post_internal_cmd = pdc_post_internal_cmd,
+ .prereset = pdc_prereset,
.error_handler = pdc_error_handler,

@@ -691,6 +693,12 @@ static void pdc_sata_thaw(struct ata_por
readl(host_mmio + hotplug_offset); /* flush */

+static int pdc_prereset(struct ata_link *link, unsigned long deadline)
+ pdc_reset_port(link->ap);
+ return ata_sff_prereset(link, deadline);
static void pdc_error_handler(struct ata_port *ap)
if (!(ap->pflags & ATA_PFLAG_FROZEN))
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