linux-kernel - Re: SATA link power management issues

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Date:	Sun, 22 Feb 2015 21:53:35 +0100
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-ide@...r.kernel.org, tj@...nel.org, stripathi@....com
Subject: Re: SATA link power management issues

Hi,

It seems that the following patch prevents errors when the policy is
changed. Could anybody explain why?

Thanks,
Gabriele

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 61a9c07..38d39f7 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1708,7 +1708,10 @@ static void ahci_handle_port_interrupt(struct ata_port *ap,
 		status &= ~PORT_IRQ_BAD_PMP;
 
 	/* if LPM is enabled, PHYRDY doesn't mean anything */
-	if (ap->link.lpm_policy > ATA_LPM_MAX_POWER) {
+	if (ap->link.lpm_policy > ATA_LPM_MAX_POWER ||
+	    ap->link.flags & ATA_LFLAG_CHANGED) {
+		if (ap->link.flags & ATA_LFLAG_CHANGED)
+			ap->link.flags &= ~ATA_LFLAG_CHANGED;
 		status &= ~PORT_IRQ_PHYRDY;
 		ahci_scr_write(&ap->link, SCR_ERROR, SERR_PHYRDY_CHG);
 	}
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index d2029a4..e8f965c 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3489,6 +3489,8 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 		}
 	}
 
+	link->flags |= ATA_LFLAG_CHANGED;
+
 	return 0;
 
 fail:
diff --git a/include/linux/libata.h b/include/linux/libata.h
index fc03efa..5abf5f2 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -205,6 +205,7 @@ enum {
 	ATA_LFLAG_SW_ACTIVITY	= (1 << 7), /* keep activity stats */
 	ATA_LFLAG_NO_LPM	= (1 << 8), /* disable LPM on this link */
 	ATA_LFLAG_RST_ONCE	= (1 << 9), /* limit recovery to one reset */
+	ATA_LFLAG_CHANGED	= (1 << 10),
 
 	/* struct ata_port flags */
 	ATA_FLAG_SLAVE_POSS	= (1 << 0), /* host supports slave dev */
--
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