3.18-stable review patch. If anyone has any objections, please let me know.
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From: Srinivas Pandruvada srinivas.pandruvada@linux.intel.com
[ Upstream commit 2dbb3ec29a6c069035857a2fc4c24e80e5dfe3cc ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/ata/libahci.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -2052,6 +2052,8 @@ static void ahci_set_aggressive_devslp(s 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) |