[PATCH 3/3] [SRU Y/Z/A] nvme: explicitly disable APST on quirked devices

[Kai-Heng Feng]

BugLink: https://bugs.launchpad.net/bugs/1699004

A user reports APST is enabled, even when the NVMe is quirked or with
option "default_ps_max_latency_us=0".

The current logic will not set APST if the device is quirked. But the
NVMe in question will enable APST automatically.

Separate the logic "apst is supported" and "to enable apst", so we can
use the latter one to explicitly disable APST at initialiaztion.

BugLink: https://bugs.launchpad.net/bugs/1699004
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
Reviewed-by: Andy Lutomirski <luto at kernel.org>
Signed-off-by: Keith Busch <keith.busch at intel.com>
(backported from commit 71a8a57ce79c4f3b19c2a5c0ccecede32341cb22 git://git.infradead.org/nvme.git nvme-4.13)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 drivers/nvme/host/core.c | 19 ++++++++++---------
 drivers/nvme/host/nvme.h |  1 +
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index cdda12bd1676..c50e8cf92c8b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1246,7 +1246,7 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
 	if (!table)
 		return;
 
-	if (ctrl->ps_max_latency_us == 0) {
+	if (!ctrl->apst_enabled || ctrl->ps_max_latency_us == 0) {
 		/* Turn off APST. */
 		apste = 0;
 		dev_dbg(ctrl->device, "APST disabled\n");
@@ -1410,7 +1410,7 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	u64 cap;
 	int ret, page_shift;
 	u32 max_hw_sectors;
-	u8 prev_apsta;
+	bool prev_apst_enabled;
 
 	ret = ctrl->ops->reg_read32(ctrl, NVME_REG_VS, &ctrl->vs);
 	if (ret) {
@@ -1477,16 +1477,17 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->kas = le16_to_cpu(id->kas);
 
 	ctrl->npss = id->npss;
-	prev_apsta = ctrl->apsta;
+	ctrl->apsta = id->apsta;
+	prev_apst_enabled = ctrl->apst_enabled;
 	if (ctrl->quirks & NVME_QUIRK_NO_APST) {
 		if (force_apst && id->apsta) {
-			dev_warn(ctrl->dev, "forcibly allowing APST due to nvme_core.force_apst -- use at your own risk\n");
-			ctrl->apsta = 1;
+			dev_warn(ctrl->device, "forcibly allowing APST due to nvme_core.force_apst -- use at your own risk\n");
+			ctrl->apst_enabled = true;
 		} else {
-			ctrl->apsta = 0;
+			ctrl->apst_enabled = false;
 		}
 	} else {
-		ctrl->apsta = id->apsta;
+		ctrl->apst_enabled = id->apsta;
 	}
 	memcpy(ctrl->psd, id->psd, sizeof(ctrl->psd));
 
@@ -1514,9 +1515,9 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 
 	kfree(id);
 
-	if (ctrl->apsta && !prev_apsta)
+	if (ctrl->apst_enabled && !prev_apst_enabled)
 		dev_pm_qos_expose_latency_tolerance(ctrl->device);
-	else if (!ctrl->apsta && prev_apsta)
+	else if (!ctrl->apst_enabled && prev_apst_enabled)
 		dev_pm_qos_hide_latency_tolerance(ctrl->device);
 
 	nvme_configure_apst(ctrl);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 6ace64f855f4..7596ae072b5c 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -166,6 +166,7 @@ struct nvme_ctrl {
 
 	/* Power saving configuration */
 	u64 ps_max_latency_us;
+	bool apst_enabled;
 
 	/* Fabrics only */
 	u16 sqsize;
-- 
2.13.2