From 2dbb3ec29a6c069035857a2fc4c24e80e5dfe3cc Mon Sep 17 00:00:00 2001
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date: Mon, 2 Jul 2018 12:01:53 -0700
Subject: [PATCH] ata: libahci: Correct setting of DEVSLP register
Git-commit: 2dbb3ec29a6c069035857a2fc4c24e80e5dfe3cc
Patch-mainline: v4.19-rc1
References: bsc#1051510
We have seen that on some platforms, SATA device never show any DEVSLP
residency. This prevent power gating of SATA IP, which prevent system
to transition to low power mode in systems with SLP_S0 aka modern
standby systems. The PHY logic is off only in DEVSLP not in slumber.
Reference:
https://www.intel.com/content/dam/www/public/us/en/documents/datasheets
/332995-skylake-i-o-platform-datasheet-volume-1.pdf
Section 28.7.6.1
Here driver is trying to do read-modify-write the devslp register. But
not resetting the bits for which this driver will modify values (DITO,
MDAT and DETO). So simply reset those bits before updating to new values.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/ata/libahci.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index f79dce613e54..fdb7d7bf7626 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -2162,6 +2162,8 @@ static void ahci_set_aggressive_devslp(struct ata_port *ap, bool sleep)
deto = 20;
}
+ /* Make dito, mdat, deto bits to 0s */
+ devslp &= ~GENMASK_ULL(24, 2);
devslp |= ((dito << PORT_DEVSLP_DITO_OFFSET) |
(mdat << PORT_DEVSLP_MDAT_OFFSET) |
(deto << PORT_DEVSLP_DETO_OFFSET) |
--
2.18.0