sata_promise: don't classify overruns as HSM errors

When sata_promise encounters an overrun or underrun error it
translates that to a libata AC_ERR_HSM, causing a hard reset.
Since over/under-runs were thought to be rare and transient,
this action seemed reasonable.

Unfortunately it turns out that the controller throws overrun
errors when e.g. hal polls a CD or DVD writer containing blank
media, causing long sequences of hard resets and retries before
EH finally gives up.

This patch updates sata_promise to classify over/under-runs as
AC_ERR_OTHER instead. This allows libata EH and upper layers to
retry or fail the operation as they see fit without the disruption
caused by repeated hard resets.

This fixes a problem using a DVD-RAM drive with sata_promise,
reported by Thomas Schorpp. I also tested it on a DVD-RW drive.

Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Tested-by: thomas schorpp <thomas.schorpp@googlemail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_promise.c

@@ -862,7 +862,7 @@ static void pdc_error_intr(struct ata_port *ap, struct ata_queued_cmd *qc,
 	if (port_status & PDC_DRIVE_ERR)
 		ac_err_mask |= AC_ERR_DEV;
 	if (port_status & (PDC_OVERRUN_ERR | PDC_UNDERRUN_ERR))
-		ac_err_mask |= AC_ERR_HSM;
+		ac_err_mask |= AC_ERR_OTHER;
 	if (port_status & (PDC2_ATA_HBA_ERR | PDC2_ATA_DMA_CNT_ERR))
 		ac_err_mask |= AC_ERR_ATA_BUS;
 	if (port_status & (PDC_PH_ERR | PDC_SH_ERR | PDC_DH_ERR | PDC2_HTO_ERR