[PATCH v9 16/17] scsi: ufs: Forbid auto-hibernation without I/O scheduler

Bart Van Assche
2023-08-16T19:57:29Z

UFSHCI 3.0 controllers do not preserve the write order if auto-hibernation
is enabled. If the write order is not preserved, an I/O scheduler is
required to serialize zoned writes. Hence do not allow auto-hibernation
to be enabled without I/O scheduler if a zoned logical unit is present
and if the controller is operating in legacy mode. This patch has been
tested with the following shell script:

show_ah8() {
echo -n "auto_hibern8: "
adb shell "cat /sys/devices/platform/13200000.ufs/auto_hibern8"
}

set_ah8() {
local rc
adb shell "echo $1 > /sys/devices/platform/13200000.ufs/auto_hibern8"
rc=$?
show_ah8
return $rc
}

set_iosched() {
adb shell "echo $1 >/sys/class/block/$zoned_bdev/queue/scheduler &&
echo -n 'I/O scheduler: ' &&
cat /sys/class/block/sde/queue/scheduler"
}

adb root
zoned_bdev=$(adb shell grep -lvw 0 /sys/class/block/sd*/queue/chunk_sectors |&
sed 's|/sys/class/block/||g;s|/queue/chunk_sectors||g')
[ -n "$zoned_bdev" ]
show_ah8
set_ah8 0
set_iosched none
if set_ah8 150000; then
echo "Error: enabled AH8 without I/O scheduler"
fi
set_iosched mq-deadline
set_ah8 150000

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Can Guo <quic_cang@quicinc.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/ufs/core/ufs-sysfs.c | 2 +-
drivers/ufs/core/ufshcd-priv.h | 1 -
drivers/ufs/core/ufshcd.c | 60 ++++++++++++++++++++++++++++++++--
include/ufs/ufshcd.h | 2 +-
4 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/drivers/ufs/core/ufs-sysfs.c b/drivers/ufs/core/ufs-sysfs.c
index 6c72075750dd..a693dea1bd18 100644
--- a/drivers/ufs/core/ufs-sysfs.c
+++ b/drivers/ufs/core/ufs-sysfs.c
@@ -203,7 +203,7 @@ static ssize_t auto_hibern8_store(struct device *dev,
goto out;
}

- ufshcd_auto_hibern8_update(hba, ufshcd_us_to_ahit(timer));
+ ret = ufshcd_auto_hibern8_update(hba, ufshcd_us_to_ahit(timer));

out:
up(&hba->host_sem);
diff --git a/drivers/ufs/core/ufshcd-priv.h b/drivers/ufs/core/ufshcd-priv.h
index 0f3bd943b58b..a2b74fbc2056 100644
--- a/drivers/ufs/core/ufshcd-priv.h
+++ b/drivers/ufs/core/ufshcd-priv.h
@@ -60,7 +60,6 @@ int ufshcd_query_attr(struct ufs_hba *hba, enum query_opcode opcode,
enum attr_idn idn, u8 index, u8 selector, u32 *attr_val);
int ufshcd_query_flag(struct ufs_hba *hba, enum query_opcode opcode,
enum flag_idn idn, u8 index, bool *flag_res);
-void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
struct cq_entry *cqe);
int ufshcd_mcq_init(struct ufs_hba *hba);
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 39000c018d8b..37d430d20939 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -4337,6 +4337,29 @@ int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)
}
EXPORT_SYMBOL_GPL(ufshcd_uic_hibern8_exit);

+static int ufshcd_update_preserves_write_order(struct ufs_hba *hba,
+ bool preserves_write_order)
+{
+ struct scsi_device *sdev;
+
+ if (!preserves_write_order) {
+ shost_for_each_device(sdev, hba->host) {
+ struct request_queue *q = sdev->request_queue;
+
+ /*
+ * This code does not check whether the attached I/O
+ * scheduler serializes zoned writes
+ * (ELEVATOR_F_ZBD_SEQ_WRITE) because this cannot be
+ * checked from outside the block layer core.
+ */
+ if (blk_queue_is_zoned(q) && !q->elevator)
+ return -EPERM;
+ }
+ }
+
+ return 0;
+}
+
static void ufshcd_configure_auto_hibern8(struct ufs_hba *hba)
{
if (!ufshcd_is_auto_hibern8_supported(hba))
@@ -4345,13 +4368,37 @@ static void ufshcd_configure_auto_hibern8(struct ufs_hba *hba)
ufshcd_writel(hba, hba->ahit, REG_AUTO_HIBERNATE_IDLE_TIMER);
}

-void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
+/**
+ * ufshcd_auto_hibern8_update() - Modify the auto-hibernation control register
+ * @hba: per-adapter instance
+ * @ahit: New auto-hibernate settings. Includes the scale and the value of the
+ * auto-hibernation timer. See also the UFSHCI_AHIBERN8_TIMER_MASK and
+ * UFSHCI_AHIBERN8_SCALE_MASK constants.
+ *
+ * Note: enabling auto-hibernation if a zoned logical unit is present without
+ * attaching the mq-deadline scheduler first to the zoned logical unit may cause
+ * unaligned write errors for the zoned logical unit.
+ */
+int ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
{
const u32 cur_ahit = READ_ONCE(hba->ahit);
+ bool prev_state, new_state;
+ int ret;

if (!ufshcd_is_auto_hibern8_supported(hba) || cur_ahit == ahit)
- return;
+ return 0;

+ prev_state = FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, cur_ahit);
+ new_state = FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, ahit);
+
+ if (!is_mcq_enabled(hba) && !prev_state && new_state) {
+ /*
+ * Auto-hibernation will be enabled for legacy UFSHCI mode.
+ */
+ ret = ufshcd_update_preserves_write_order(hba, false);
+ if (ret)
+ return ret;
+ }
WRITE_ONCE(hba->ahit, ahit);
if (!pm_runtime_suspended(&hba->ufs_device_wlun->sdev_gendev)) {
ufshcd_rpm_get_sync(hba);
@@ -4360,6 +4407,15 @@ void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit)
ufshcd_release(hba);
ufshcd_rpm_put_sync(hba);
}
+ if (!is_mcq_enabled(hba) && prev_state && !new_state) {
+ /*
+ * Auto-hibernation has been disabled.
+ */
+ ret = ufshcd_update_preserves_write_order(hba, true);
+ WARN_ON_ONCE(ret);
+ }
+
+ return 0;
}
EXPORT_SYMBOL_GPL(ufshcd_auto_hibern8_update);

diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 040d66d99912..7ae071a6811c 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -1363,7 +1363,7 @@ static inline int ufshcd_disable_host_tx_lcc(struct ufs_hba *hba)
return ufshcd_dme_set(hba, UIC_ARG_MIB(PA_LOCAL_TX_LCC_ENABLE), 0);
}

-void ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
+int ufshcd_auto_hibern8_update(struct ufs_hba *hba, u32 ahit);
void ufshcd_fixup_dev_quirks(struct ufs_hba *hba,
const struct ufs_dev_quirk *fixups);
#define SD_ASCII_STD true