From: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxxxx> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- drivers/ata/libahci.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index d81b984b72e4..f233ce60a678 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -2132,6 +2132,8 @@ 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) | -- 2.17.1
