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From:   Sasha Levin <Alexander.Levin@microsoft.com>
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Tejun Heo <tj@kernel.org>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL 4.14 41/89] ata: libahci: Allow reconfigure of DEVSLP
 register
Thread-Topic: [PATCH AUTOSEL 4.14 41/89] ata: libahci: Allow reconfigure of
 DEVSLP register
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Date:   Sun, 2 Sep 2018 13:06:57 +0000
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From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

[ Upstream commit 11c291461b6ea8d1195a96d6bba6673a94aacebc ]

There are two modes in which DEVSLP can be entered. The OS initiated or
hardware autonomous.

In hardware autonomous mode, BIOS configures the AHCI controller and the
device to enable DEVSLP. But they may not be ideal for all cases. So in
this case, OS should be able to reconfigure DEVSLP register.

Currently if the DEVSLP is already enabled, we can't set again as it will
simply return. There are some systems where the firmware is setting high
DITO by default, in this case we can't modify here to correct settings.
With the default in several seconds, we are not able to transition to
DEVSLP.

This change will allow reconfiguration of devslp register if DITO is
different.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 drivers/ata/libahci.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index bc562fd2b0a0..25edaf8f9629 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -2096,7 +2096,7 @@ static void ahci_set_aggressive_devslp(struct ata_por=
t *ap, bool sleep)
 	struct ahci_host_priv *hpriv =3D ap->host->private_data;
 	void __iomem *port_mmio =3D ahci_port_base(ap);
 	struct ata_device *dev =3D ap->link.device;
-	u32 devslp, dm, dito, mdat, deto;
+	u32 devslp, dm, dito, mdat, deto, dito_conf;
 	int rc;
 	unsigned int err_mask;
=20
@@ -2120,8 +2120,15 @@ static void ahci_set_aggressive_devslp(struct ata_po=
rt *ap, bool sleep)
 		return;
 	}
=20
-	/* device sleep was already enabled */
-	if (devslp & PORT_DEVSLP_ADSE)
+	dm =3D (devslp & PORT_DEVSLP_DM_MASK) >> PORT_DEVSLP_DM_OFFSET;
+	dito =3D devslp_idle_timeout / (dm + 1);
+	if (dito > 0x3ff)
+		dito =3D 0x3ff;
+
+	dito_conf =3D (devslp >> PORT_DEVSLP_DITO_OFFSET) & 0x3FF;
+
+	/* device sleep was already enabled and same dito */
+	if ((devslp & PORT_DEVSLP_ADSE) && (dito_conf =3D=3D dito))
 		return;
=20
 	/* set DITO, MDAT, DETO and enable DevSlp, need to stop engine first */
@@ -2129,11 +2136,6 @@ static void ahci_set_aggressive_devslp(struct ata_po=
rt *ap, bool sleep)
 	if (rc)
 		return;
=20
-	dm =3D (devslp & PORT_DEVSLP_DM_MASK) >> PORT_DEVSLP_DM_OFFSET;
-	dito =3D devslp_idle_timeout / (dm + 1);
-	if (dito > 0x3ff)
-		dito =3D 0x3ff;
-
 	/* Use the nominal value 10 ms if the read MDAT is zero,
 	 * the nominal value of DETO is 20 ms.
 	 */
--=20
2.17.1