ata: ahci: Support state with min power but Partial low power state

Currently when min_power policy is selected, the partial low power state
is not entered and link will try aggressively enter to only slumber state.
Add a new policy which still enable DEVSLP but also try to enter partial
low power state. This policy is presented as "min_power_with_partial".

For information the difference between partial and slumber
Partial – PHY logic is powered up, and in a reduced power state. The link
PM exit latency to active state maximum is 10 ns.
Slumber – PHY logic is powered up, and in a reduced power state. The link
PM exit latency to active state maximum is 10 ms.
Devslp – PHY logic is powered down. The link PM exit latency from this
state to active state maximum is 20 ms, unless otherwise specified by
DETO.

Suggested-and-reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 5038cee7d982..f79dce613e54 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -800,6 +800,8 @@ static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
                         cmd |= PORT_CMD_ALPE;
                         if (policy == ATA_LPM_MIN_POWER)
                                 cmd |= PORT_CMD_ASP;
+                        else if (policy == ATA_LPM_MIN_POWER_WITH_PARTIAL)
+                                cmd &= ~PORT_CMD_ASP;
 
                         /* write out new cmd value */
                         writel(cmd, port_mmio + PORT_CMD);
@@ -810,7 +812,8 @@ static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
         if ((hpriv->cap2 & HOST_CAP2_SDS) &&
             (hpriv->cap2 & HOST_CAP2_SADM) &&
             (link->device->flags & ATA_DFLAG_DEVSLP)) {
-                if (policy == ATA_LPM_MIN_POWER)
+                if (policy == ATA_LPM_MIN_POWER ||
+                    policy == ATA_LPM_MIN_POWER_WITH_PARTIAL)
                         ahci_set_aggressive_devslp(ap, true);
                 else
                         ahci_set_aggressive_devslp(ap, false);