[PATCH v3 0/9] Add Host control mode to HPB

[PATCH v3 0/9] Add Host control mode to HPB

[Avri Altman]

v2 -> v3:
 - Attend Greg's and Can's comments
 - rebase on Daejun's v21

v1 -> v2:
 - attend Greg's and Daejun's comments
 - add patch 9 making host mode parameters configurable
 - rebase on Daejun's v19


The HPB spec defines 2 control modes - device control mode and host
control mode. In oppose to device control mode, in which the host obey
to whatever recommendation received from the device - In host control
mode, the host uses its own algorithms to decide which regions should
be activated or inactivated.

We kept the host managed heuristic simple and concise.

Aside from adding a by-spec functionality, host control mode entails
some further potential benefits: makes the hpb logic transparent and
readable, while allow tuning / scaling its various parameters, and
utilize system-wide info to optimize HPB potential.

This series is based on Samsung's V19 device-control HPB2.0 driver, see
msg-id: 20210218090853epcms2p8ccac0b5611dec22afd04ecc06e74498e@epcms2p8
in lore.kernel.org. The patches are also available in wdc ufs repo:
https://github.com/westerndigitalcorporation/WDC-UFS-REPO/tree/hpb-v21

This version was tested on Galaxy S20, and Xiaomi Mi10 pro.
Your meticulous review and testing is mostly welcome and appreciated.

Thanks,
Avri

Avri Altman (9):
  scsi: ufshpb: Cache HPB Control mode on init
  scsi: ufshpb: Add host control mode support to rsp_upiu
  scsi: ufshpb: Add region's reads counter
  scsi: ufshpb: Make eviction depends on region's reads
  scsi: ufshpb: Region inactivation in host mode
  scsi: ufshpb: Add hpb dev reset response
  scsi: ufshpb: Add "Cold" regions timer
  scsi: ufshpb: Add support for host control mode
  scsi: ufshpb: Make host mode parameters configurable

 Documentation/ABI/testing/sysfs-driver-ufs |  68 +++
 drivers/scsi/ufs/ufshcd.h                  |   2 +
 drivers/scsi/ufs/ufshpb.c                  | 622 +++++++++++++++++++--
 drivers/scsi/ufs/ufshpb.h                  |  44 +-
 4 files changed, 691 insertions(+), 45 deletions(-)

-- 
2.25.1

[PATCH v3 1/9] scsi: ufshpb: Cache HPB Control mode on init

[Avri Altman]

We will use it later, when we'll need to differentiate between device
and host control modes.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshcd.h | 2 ++
 drivers/scsi/ufs/ufshpb.c | 8 +++++---
 drivers/scsi/ufs/ufshpb.h | 2 ++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 49bfebf366c7..1a8dcdaa357a 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -655,6 +655,7 @@ struct ufs_hba_variant_params {
  * @slave_conf_cnt: counter to check all lu finished initialization
  * @hpb_disabled: flag to check if HPB is disabled
  * @max_hpb_single_cmd: maximum size of single HPB command
+ * @control_mode: either host or device
  */
 struct ufshpb_dev_info {
 	int num_lu;
@@ -663,6 +664,7 @@ struct ufshpb_dev_info {
 	atomic_t slave_conf_cnt;
 	bool hpb_disabled;
 	int max_hpb_single_cmd;
+	u8 control_mode;
 };
 #endif
 
diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index e97a78400f68..f9140f3a4eed 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -1522,6 +1522,9 @@ static void ufshpb_lu_parameter_init(struct ufs_hba *hba,
 				 % (hpb->srgn_mem_size / HPB_ENTRY_SIZE);
 
 	hpb->pages_per_srgn = DIV_ROUND_UP(hpb->srgn_mem_size, PAGE_SIZE);
+
+	if (hpb_dev_info->control_mode == HPB_HOST_CONTROL)
+		hpb->is_hcm = true;
 }
 
 static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
@@ -2205,11 +2208,10 @@ void ufshpb_get_dev_info(struct ufs_hba *hba, u8 *desc_buf)
 {
 	struct ufshpb_dev_info *hpb_dev_info = &hba->ufshpb_dev;
 	int version, ret;
-	u8 hpb_mode;
 	u32 max_hpb_sigle_cmd = 0;
 
-	hpb_mode = desc_buf[DEVICE_DESC_PARAM_HPB_CONTROL];
-	if (hpb_mode == HPB_HOST_CONTROL) {
+	hpb_dev_info->control_mode = desc_buf[DEVICE_DESC_PARAM_HPB_CONTROL];
+	if (hpb_dev_info->control_mode == HPB_HOST_CONTROL) {
 		dev_err(hba->dev, "%s: host control mode is not supported.\n",
 			__func__);
 		hpb_dev_info->hpb_disabled = true;
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index eb8366d47d8a..f55a71b250eb 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -223,6 +223,8 @@ struct ufshpb_lu {
 	u32 entries_per_srgn_shift;
 	u32 pages_per_srgn;
 
+	bool is_hcm;
+
 	struct ufshpb_stats stats;
 	struct ufshpb_params params;
 
-- 
2.25.1

[PATCH v3 2/9] scsi: ufshpb: Add host control mode support to rsp_upiu

[Avri Altman]

In device control mode, the device may recommend the host to either
activate or inactivate a region, and the host should follow. Meaning
those are not actually recommendations, but more of instructions.

On the contrary, in host control mode, the recommendation protocol is
slightly changed:
a) The device may only recommend the host to update a subregion of an
   already-active region. And,
b) The device may *not* recommend to inactivate a region.

Furthermore, in host control mode, the host may choose not to follow any
of the device's recommendations. However, in case of a recommendation to
update an active and clean subregion, it is better to follow those
recommendation because otherwise the host has no other way to know that
some internal relocation took place.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 34 +++++++++++++++++++++++++++++++++-
 drivers/scsi/ufs/ufshpb.h |  2 ++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index f9140f3a4eed..e052260868ad 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -156,6 +156,8 @@ static void ufshpb_set_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
 	else
 		set_bit_len = cnt;
 
+	set_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
+
 	if (rgn->rgn_state != HPB_RGN_INACTIVE &&
 	    srgn->srgn_state == HPB_SRGN_VALID)
 		bitmap_set(srgn->mctx->ppn_dirty, srgn_offset, set_bit_len);
@@ -222,6 +224,11 @@ static bool ufshpb_test_ppn_dirty(struct ufshpb_lu *hpb, int rgn_idx,
 	return false;
 }
 
+static inline bool is_rgn_dirty(struct ufshpb_region *rgn)
+{
+	return test_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
+}
+
 static int ufshpb_fill_ppn_from_page(struct ufshpb_lu *hpb,
 			  struct ufshpb_map_ctx *mctx, int pos, int len,
 			  u64 *ppn_buf)
@@ -715,6 +722,7 @@ static void ufshpb_put_map_req(struct ufshpb_lu *hpb,
 static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
 				     struct ufshpb_subregion *srgn)
 {
+	struct ufshpb_region *rgn;
 	u32 num_entries = hpb->entries_per_srgn;
 
 	WARN_ON(!srgn->mctx);
@@ -723,6 +731,10 @@ static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
 		num_entries = hpb->last_srgn_entries;
 
 	bitmap_zero(srgn->mctx->ppn_dirty, num_entries);
+
+	rgn = hpb->rgn_tbl + srgn->rgn_idx;
+	clear_bit(RGN_FLAG_DIRTY, &rgn->rgn_flags);
+
 	return 0;
 }
 
@@ -1171,6 +1183,18 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 		srgn_i =
 			be16_to_cpu(rsp_field->hpb_active_field[i].active_srgn);
 
+		rgn = hpb->rgn_tbl + rgn_i;
+		if (hpb->is_hcm &&
+		    (rgn->rgn_state != HPB_RGN_ACTIVE || is_rgn_dirty(rgn))) {
+			/*
+			 * in host control mode, subregion activation
+			 * recommendations are only allowed to active regions.
+			 * Also, ignore recommendations for dirty regions - the
+			 * host will make decisions concerning those by himself
+			 */
+			continue;
+		}
+
 		dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
 			"activate(%d) region %d - %d\n", i, rgn_i, srgn_i);
 
@@ -1178,7 +1202,6 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 		ufshpb_update_active_info(hpb, rgn_i, srgn_i);
 		spin_unlock(&hpb->rsp_list_lock);
 
-		rgn = hpb->rgn_tbl + rgn_i;
 		srgn = rgn->srgn_tbl + srgn_i;
 
 		/* blocking HPB_READ */
@@ -1189,6 +1212,14 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 		hpb->stats.rb_active_cnt++;
 	}
 
+	if (hpb->is_hcm) {
+		/*
+		 * in host control mode the device is not allowed to inactivate
+		 * regions
+		 */
+		goto out;
+	}
+
 	for (i = 0; i < rsp_field->inactive_rgn_cnt; i++) {
 		rgn_i = be16_to_cpu(rsp_field->hpb_inactive_field[i]);
 		dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
@@ -1213,6 +1244,7 @@ static void ufshpb_rsp_req_region_update(struct ufshpb_lu *hpb,
 		hpb->stats.rb_inactive_cnt++;
 	}
 
+out:
 	dev_dbg(&hpb->sdev_ufs_lu->sdev_dev, "Noti: #ACT %u #INACT %u\n",
 		rsp_field->active_rgn_cnt, rsp_field->inactive_rgn_cnt);
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index f55a71b250eb..8e6c2a5b80a0 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -115,6 +115,8 @@ struct ufshpb_region {
 
 	/* below information is used by lru */
 	struct list_head list_lru_rgn;
+	unsigned long rgn_flags;
+#define RGN_FLAG_DIRTY 0
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
-- 
2.25.1

[PATCH v3 3/9] scsi: ufshpb: Add region's reads counter

[Avri Altman]

In host control mode, reads are the major source of activation trials.
Keep track of those reads counters, for both active as well inactive
regions.

We reset the read counter upon write - we are only interested in "clean"
reads.  less intuitive however, is that we also reset it upon region's
deactivation.  Region deactivation is often due to the fact that
eviction took place: a region become active on the expense of another.
This is happening when the max-active-regions limit has crossed. If we
don’t reset the counter, we will trigger a lot of trashing of the HPB
database, since few reads (or even one) to the region that was
deactivated, will trigger a re-activation trial.

Keep those counters normalized, as we are using those reads as a
comparative score, to make various decisions.
If during consecutive normalizations an active region has exhaust its
reads - inactivate it.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 108 ++++++++++++++++++++++++++++++++------
 drivers/scsi/ufs/ufshpb.h |   7 +++
 2 files changed, 100 insertions(+), 15 deletions(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index e052260868ad..348185964c32 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -16,6 +16,8 @@
 #include "ufshpb.h"
 #include "../sd.h"
 
+#define ACTIVATION_THRESHOLD 4 /* 4 IOs */
+
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
 static mempool_t *ufshpb_mctx_pool;
@@ -570,6 +572,21 @@ static int ufshpb_issue_pre_req(struct ufshpb_lu *hpb, struct scsi_cmnd *cmd,
 	return ret;
 }
 
+static void ufshpb_update_active_info(struct ufshpb_lu *hpb, int rgn_idx,
+				      int srgn_idx)
+{
+	struct ufshpb_region *rgn;
+	struct ufshpb_subregion *srgn;
+
+	rgn = hpb->rgn_tbl + rgn_idx;
+	srgn = rgn->srgn_tbl + srgn_idx;
+
+	list_del_init(&rgn->list_inact_rgn);
+
+	if (list_empty(&srgn->list_act_srgn))
+		list_add_tail(&srgn->list_act_srgn, &hpb->lh_act_srgn);
+}
+
 /*
  * This function will set up HPB read command using host-side L2P map data.
  */
@@ -616,12 +633,45 @@ int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 		ufshpb_set_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
 				 transfer_len);
 		spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+
+		if (hpb->is_hcm) {
+			spin_lock_irqsave(&rgn->rgn_lock, flags);
+			rgn->reads = 0;
+			spin_unlock_irqrestore(&rgn->rgn_lock, flags);
+		}
+
 		return 0;
 	}
 
 	if (!ufshpb_is_support_chunk(hpb, transfer_len))
 		return 0;
 
+	if (hpb->is_hcm) {
+		bool activate = false;
+		/*
+		 * in host control mode, reads are the main source for
+		 * activation trials.
+		 */
+		spin_lock_irqsave(&rgn->rgn_lock, flags);
+		rgn->reads++;
+		if (rgn->reads == ACTIVATION_THRESHOLD)
+			activate = true;
+		spin_unlock_irqrestore(&rgn->rgn_lock, flags);
+		if (activate) {
+			spin_lock_irqsave(&hpb->rsp_list_lock, flags);
+			ufshpb_update_active_info(hpb, rgn_idx, srgn_idx);
+			hpb->stats.rb_active_cnt++;
+			spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
+			dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
+				"activate region %d-%d\n", rgn_idx, srgn_idx);
+		}
+
+		/* keep those counters normalized */
+		if (rgn->reads > hpb->entries_per_srgn &&
+		    !test_and_set_bit(WORK_PENDING, &hpb->work_data_bits))
+			schedule_work(&hpb->ufshpb_normalization_work);
+	}
+
 	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
 	if (ufshpb_test_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
 				   transfer_len)) {
@@ -738,21 +788,6 @@ static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
 	return 0;
 }
 
-static void ufshpb_update_active_info(struct ufshpb_lu *hpb, int rgn_idx,
-				      int srgn_idx)
-{
-	struct ufshpb_region *rgn;
-	struct ufshpb_subregion *srgn;
-
-	rgn = hpb->rgn_tbl + rgn_idx;
-	srgn = rgn->srgn_tbl + srgn_idx;
-
-	list_del_init(&rgn->list_inact_rgn);
-
-	if (list_empty(&srgn->list_act_srgn))
-		list_add_tail(&srgn->list_act_srgn, &hpb->lh_act_srgn);
-}
-
 static void ufshpb_update_inactive_info(struct ufshpb_lu *hpb, int rgn_idx)
 {
 	struct ufshpb_region *rgn;
@@ -998,6 +1033,14 @@ static void __ufshpb_evict_region(struct ufshpb_lu *hpb,
 
 	ufshpb_cleanup_lru_info(lru_info, rgn);
 
+	if (hpb->is_hcm) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&rgn->rgn_lock, flags);
+		rgn->reads = 0;
+		spin_unlock_irqrestore(&rgn->rgn_lock, flags);
+	}
+
 	for_each_sub_region(rgn, srgn_idx, srgn)
 		ufshpb_purge_active_subregion(hpb, srgn);
 }
@@ -1420,6 +1463,36 @@ static void ufshpb_run_inactive_region_list(struct ufshpb_lu *hpb)
 	spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
 }
 
+static void ufshpb_normalization_work_handler(struct work_struct *work)
+{
+	struct ufshpb_lu *hpb;
+	int rgn_idx;
+
+	hpb = container_of(work, struct ufshpb_lu, ufshpb_normalization_work);
+
+	for (rgn_idx = 0; rgn_idx < hpb->rgns_per_lu; rgn_idx++) {
+		struct ufshpb_region *rgn = hpb->rgn_tbl + rgn_idx;
+
+		if (rgn->reads) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&rgn->rgn_lock, flags);
+			rgn->reads = (rgn->reads >> 1);
+			spin_unlock_irqrestore(&rgn->rgn_lock, flags);
+		}
+
+		if (rgn->rgn_state != HPB_RGN_ACTIVE || rgn->reads)
+			continue;
+
+		/* if region is active but has no reads - inactivate it */
+		spin_lock(&hpb->rsp_list_lock);
+		ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
+		spin_unlock(&hpb->rsp_list_lock);
+	}
+
+	clear_bit(WORK_PENDING, &hpb->work_data_bits);
+}
+
 static void ufshpb_map_work_handler(struct work_struct *work)
 {
 	struct ufshpb_lu *hpb = container_of(work, struct ufshpb_lu, map_work);
@@ -1810,6 +1883,9 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 	INIT_LIST_HEAD(&hpb->list_hpb_lu);
 
 	INIT_WORK(&hpb->map_work, ufshpb_map_work_handler);
+	if (hpb->is_hcm)
+		INIT_WORK(&hpb->ufshpb_normalization_work,
+			  ufshpb_normalization_work_handler);
 
 	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
 			  sizeof(struct ufshpb_req), 0, 0, NULL);
@@ -1909,6 +1985,8 @@ static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
 
 static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
 {
+	if (hpb->is_hcm)
+		cancel_work_sync(&hpb->ufshpb_normalization_work);
 	cancel_work_sync(&hpb->map_work);
 }
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 8e6c2a5b80a0..0a41df919f06 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -117,6 +117,10 @@ struct ufshpb_region {
 	struct list_head list_lru_rgn;
 	unsigned long rgn_flags;
 #define RGN_FLAG_DIRTY 0
+
+	/* region reads - for host mode */
+	spinlock_t rgn_lock;
+	unsigned int reads;
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
@@ -207,6 +211,9 @@ struct ufshpb_lu {
 
 	/* for selecting victim */
 	struct victim_select_info lru_info;
+	struct work_struct ufshpb_normalization_work;
+	unsigned long work_data_bits;
+#define WORK_PENDING 0
 
 	/* pinned region information */
 	u32 lu_pinned_start;
-- 
2.25.1

[PATCH v3 4/9] scsi: ufshpb: Make eviction depends on region's reads

[Avri Altman]

In host mode, eviction is considered an extreme measure.
verify that the entering region has enough reads, and the exiting
region has much less reads.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 348185964c32..9cb17c97cf93 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -17,6 +17,7 @@
 #include "../sd.h"
 
 #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
+#define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -995,6 +996,13 @@ static struct ufshpb_region *ufshpb_victim_lru_info(struct ufshpb_lu *hpb)
 		if (ufshpb_check_srgns_issue_state(hpb, rgn))
 			continue;
 
+		/*
+		 * in host control mode, verify that the exiting region
+		 * has less reads
+		 */
+		if (hpb->is_hcm && rgn->reads > (EVICTION_THRESHOLD >> 1))
+			continue;
+
 		victim_rgn = rgn;
 		break;
 	}
@@ -1150,7 +1158,7 @@ static int ufshpb_issue_map_req(struct ufshpb_lu *hpb,
 
 static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 {
-	struct ufshpb_region *victim_rgn;
+	struct ufshpb_region *victim_rgn = NULL;
 	struct victim_select_info *lru_info = &hpb->lru_info;
 	unsigned long flags;
 	int ret = 0;
@@ -1178,6 +1186,16 @@ static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 			 * because the device could detect this region
 			 * by not issuing HPB_READ
 			 */
+
+			/*
+			 * in host control mode, verify that the entering
+			 * region has enough reads
+			 */
+			if (hpb->is_hcm && rgn->reads < EVICTION_THRESHOLD) {
+				ret = -EACCES;
+				goto out;
+			}
+
 			victim_rgn = ufshpb_victim_lru_info(hpb);
 			if (!victim_rgn) {
 				dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
-- 
2.25.1

[PATCH v3 5/9] scsi: ufshpb: Region inactivation in host mode

[Avri Altman]

I host mode, the host is expected to send HPB-WRITE-BUFFER with
buffer-id = 0x1 when it inactivates a region.

Use the map-requests pool as there is no point in assigning a
designated cache for umap-requests.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 120 ++++++++++++++++++++++++++++++++------
 drivers/scsi/ufs/ufshpb.h |   5 +-
 2 files changed, 105 insertions(+), 20 deletions(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 9cb17c97cf93..3435a5507853 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -717,16 +717,15 @@ int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 	return 0;
 }
 
-static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
-					     struct ufshpb_subregion *srgn)
+static struct ufshpb_req *ufshpb_get_req(struct ufshpb_lu *hpb,
+					 int rgn_idx, enum req_opf dir)
 {
-	struct ufshpb_req *map_req;
+	struct ufshpb_req *rq;
 	struct request *req;
-	struct bio *bio;
 	int retries = HPB_MAP_REQ_RETRIES;
 
-	map_req = kmem_cache_alloc(hpb->map_req_cache, GFP_KERNEL);
-	if (!map_req)
+	rq = kmem_cache_alloc(hpb->map_req_cache, GFP_KERNEL);
+	if (!rq)
 		return NULL;
 
 retry:
@@ -738,36 +737,57 @@ static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
 		goto retry;
 	}
 
+	req = blk_get_request(hpb->sdev_ufs_lu->request_queue,
+			      dir, 0);
 	if (IS_ERR(req))
-		goto free_map_req;
+		goto free_rq;
+
+	rq->hpb = hpb;
+	rq->req = req;
+	rq->rb.rgn_idx = rgn_idx;
+
+	return rq;
+
+free_rq:
+	kmem_cache_free(hpb->map_req_cache, rq);
+	return NULL;
+}
+
+static void ufshpb_put_req(struct ufshpb_lu *hpb, struct ufshpb_req *rq)
+{
+	blk_put_request(rq->req);
+	kmem_cache_free(hpb->map_req_cache, rq);
+}
+
+static struct ufshpb_req *ufshpb_get_map_req(struct ufshpb_lu *hpb,
+					     struct ufshpb_subregion *srgn)
+{
+	struct ufshpb_req *map_req;
+	struct bio *bio;
+
+	map_req = ufshpb_get_req(hpb, srgn->rgn_idx, REQ_OP_SCSI_IN);
+	if (!map_req)
+		return NULL;
 
 	bio = bio_alloc(GFP_KERNEL, hpb->pages_per_srgn);
 	if (!bio) {
-		blk_put_request(req);
-		goto free_map_req;
+		ufshpb_put_req(hpb, map_req);
+		return NULL;
 	}
 
-	map_req->hpb = hpb;
-	map_req->req = req;
 	map_req->bio = bio;
 
-	map_req->rb.rgn_idx = srgn->rgn_idx;
 	map_req->rb.srgn_idx = srgn->srgn_idx;
 	map_req->rb.mctx = srgn->mctx;
 
 	return map_req;
-
-free_map_req:
-	kmem_cache_free(hpb->map_req_cache, map_req);
-	return NULL;
 }
 
 static void ufshpb_put_map_req(struct ufshpb_lu *hpb,
-				      struct ufshpb_req *map_req)
+			       struct ufshpb_req *map_req)
 {
 	bio_put(map_req->bio);
-	blk_put_request(map_req->req);
-	kmem_cache_free(hpb->map_req_cache, map_req);
+	ufshpb_put_req(hpb, map_req);
 }
 
 static int ufshpb_clear_dirty_bitmap(struct ufshpb_lu *hpb,
@@ -829,6 +849,13 @@ static void ufshpb_activate_subregion(struct ufshpb_lu *hpb,
 	srgn->srgn_state = HPB_SRGN_VALID;
 }
 
+static void ufshpb_umap_req_compl_fn(struct request *req, blk_status_t error)
+{
+	struct ufshpb_req *umap_req = (struct ufshpb_req *)req->end_io_data;
+
+	ufshpb_put_req(umap_req->hpb, umap_req);
+}
+
 static void ufshpb_map_req_compl_fn(struct request *req, blk_status_t error)
 {
 	struct ufshpb_req *map_req = (struct ufshpb_req *) req->end_io_data;
@@ -847,6 +874,14 @@ static void ufshpb_map_req_compl_fn(struct request *req, blk_status_t error)
 	ufshpb_put_map_req(map_req->hpb, map_req);
 }
 
+static void ufshpb_set_unmap_cmd(unsigned char *cdb, int rgn_idx)
+{
+	cdb[0] = UFSHPB_WRITE_BUFFER;
+	cdb[1] = UFSHPB_WRITE_BUFFER_ID;
+	put_unaligned_be16(rgn_idx, &cdb[2]);
+	cdb[9] = 0x00;
+}
+
 static void ufshpb_set_read_buf_cmd(unsigned char *cdb, int rgn_idx,
 					   int srgn_idx, int srgn_mem_size)
 {
@@ -860,6 +895,27 @@ static void ufshpb_set_read_buf_cmd(unsigned char *cdb, int rgn_idx,
 	cdb[9] = 0x00;
 }
 
+static int ufshpb_execute_umap_req(struct ufshpb_lu *hpb,
+				   struct ufshpb_req *umap_req)
+{
+	struct request_queue *q;
+	struct request *req;
+	struct scsi_request *rq;
+
+	q = hpb->sdev_ufs_lu->request_queue;
+	req = umap_req->req;
+	req->timeout = 0;
+	req->end_io_data = (void *)umap_req;
+	rq = scsi_req(req);
+	ufshpb_set_unmap_cmd(rq->cmd, umap_req->rb.rgn_idx);
+	rq->cmd_len = HPB_WRITE_BUFFER_CMD_LENGTH;
+
+	blk_execute_rq_nowait(q, NULL, req, 1, ufshpb_umap_req_compl_fn);
+
+	hpb->stats.umap_req_cnt++;
+	return 0;
+}
+
 static int ufshpb_execute_map_req(struct ufshpb_lu *hpb,
 				  struct ufshpb_req *map_req, bool last)
 {
@@ -1028,6 +1084,25 @@ static void ufshpb_purge_active_subregion(struct ufshpb_lu *hpb,
 	}
 }
 
+static int ufshpb_issue_umap_req(struct ufshpb_lu *hpb,
+				 struct ufshpb_region *rgn)
+{
+	struct ufshpb_req *umap_req;
+
+	umap_req = ufshpb_get_req(hpb, rgn->rgn_idx, REQ_OP_SCSI_OUT);
+	if (!umap_req)
+		return -ENOMEM;
+
+	if (ufshpb_execute_umap_req(hpb, umap_req))
+		goto free_umap_req;
+
+	return 0;
+
+free_umap_req:
+	ufshpb_put_req(hpb, umap_req);
+	return -EAGAIN;
+}
+
 static void __ufshpb_evict_region(struct ufshpb_lu *hpb,
 				  struct ufshpb_region *rgn)
 {
@@ -1035,6 +1110,10 @@ static void __ufshpb_evict_region(struct ufshpb_lu *hpb,
 	struct ufshpb_subregion *srgn;
 	int srgn_idx;
 
+
+	if (hpb->is_hcm && ufshpb_issue_umap_req(hpb, rgn))
+		return;
+
 	lru_info = &hpb->lru_info;
 
 	dev_dbg(&hpb->sdev_ufs_lu->sdev_dev, "evict region %d\n", rgn->rgn_idx);
@@ -1759,6 +1838,7 @@ ufshpb_sysfs_attr_show_func(rb_noti_cnt);
 ufshpb_sysfs_attr_show_func(rb_active_cnt);
 ufshpb_sysfs_attr_show_func(rb_inactive_cnt);
 ufshpb_sysfs_attr_show_func(map_req_cnt);
+ufshpb_sysfs_attr_show_func(umap_req_cnt);
 
 static struct attribute *hpb_dev_stat_attrs[] = {
 	&dev_attr_hit_cnt.attr,
@@ -1767,6 +1847,7 @@ static struct attribute *hpb_dev_stat_attrs[] = {
 	&dev_attr_rb_active_cnt.attr,
 	&dev_attr_rb_inactive_cnt.attr,
 	&dev_attr_map_req_cnt.attr,
+	&dev_attr_umap_req_cnt.attr,
 	NULL,
 };
 
@@ -1881,6 +1962,7 @@ static void ufshpb_stat_init(struct ufshpb_lu *hpb)
 	hpb->stats.rb_active_cnt = 0;
 	hpb->stats.rb_inactive_cnt = 0;
 	hpb->stats.map_req_cnt = 0;
+	hpb->stats.umap_req_cnt = 0;
 }
 
 static void ufshpb_param_init(struct ufshpb_lu *hpb)
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 0a41df919f06..13ec49ba260d 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -36,11 +36,13 @@
 /* hpb vender defined opcode */
 #define UFSHPB_READ				0xF8
 #define UFSHPB_READ_BUFFER			0xF9
-#define UFSHPB_READ_BUFFER_ID			0x01
 #define UFSHPB_WRITE_BUFFER			0xFA
+#define UFSHPB_READ_BUFFER_ID			0x01
+#define UFSHPB_WRITE_BUFFER_ID			0x01
 #define UFSHPB_WRITE_BUFFER_PREFETCH_ID		0x02
 #define MAX_HPB_READ_ID				0x7F
 #define HPB_READ_BUFFER_CMD_LENGTH		10
+#define HPB_WRITE_BUFFER_CMD_LENGTH		10
 #define LU_ENABLED_HPB_FUNC			0x02
 
 #define HPB_RESET_REQ_RETRIES			10
@@ -182,6 +184,7 @@ struct ufshpb_stats {
 	u64 rb_inactive_cnt;
 	u64 map_req_cnt;
 	u64 pre_req_cnt;
+	u64 umap_req_cnt;
 };
 
 struct ufshpb_lu {
-- 
2.25.1

[PATCH v3 6/9] scsi: ufshpb: Add hpb dev reset response

[Avri Altman]

The spec does not define what is the host's recommended response when
the device send hpb dev reset response (oper 0x2).

We will update all active hpb regions: mark them and do that on the next
read.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 40 ++++++++++++++++++++++++++++++++++++---
 drivers/scsi/ufs/ufshpb.h |  3 +++
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 3435a5507853..15755f677097 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -658,7 +658,8 @@ int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 		if (rgn->reads == ACTIVATION_THRESHOLD)
 			activate = true;
 		spin_unlock_irqrestore(&rgn->rgn_lock, flags);
-		if (activate) {
+		if (activate ||
+		    test_and_clear_bit(RGN_FLAG_UPDATE, &rgn->rgn_flags)) {
 			spin_lock_irqsave(&hpb->rsp_list_lock, flags);
 			ufshpb_update_active_info(hpb, rgn_idx, srgn_idx);
 			hpb->stats.rb_active_cnt++;
@@ -1446,6 +1447,11 @@ void ufshpb_rsp_upiu(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 	case HPB_RSP_DEV_RESET:
 		dev_warn(&hpb->sdev_ufs_lu->sdev_dev,
 			 "UFS device lost HPB information during PM.\n");
+
+		if (hpb->is_hcm &&
+		    !test_and_set_bit(RESET_PENDING, &hpb->work_data_bits))
+			schedule_work(&hpb->ufshpb_lun_reset_work);
+
 		break;
 	default:
 		dev_notice(&hpb->sdev_ufs_lu->sdev_dev,
@@ -1560,6 +1566,27 @@ static void ufshpb_run_inactive_region_list(struct ufshpb_lu *hpb)
 	spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
 }
 
+static void ufshpb_reset_work_handler(struct work_struct *work)
+{
+	struct ufshpb_lu *hpb;
+	struct victim_select_info *lru_info;
+	struct ufshpb_region *rgn;
+	unsigned long flags;
+
+	hpb = container_of(work, struct ufshpb_lu, ufshpb_lun_reset_work);
+
+	lru_info = &hpb->lru_info;
+
+	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+
+	list_for_each_entry(rgn, &lru_info->lh_lru_rgn, list_lru_rgn)
+		set_bit(RGN_FLAG_UPDATE, &rgn->rgn_flags);
+
+	spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+
+	clear_bit(RESET_PENDING, &hpb->work_data_bits);
+}
+
 static void ufshpb_normalization_work_handler(struct work_struct *work)
 {
 	struct ufshpb_lu *hpb;
@@ -1770,6 +1797,8 @@ static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 		} else {
 			rgn->rgn_state = HPB_RGN_INACTIVE;
 		}
+
+		rgn->rgn_flags = 0;
 	}
 
 	return 0;
@@ -1983,9 +2012,12 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 	INIT_LIST_HEAD(&hpb->list_hpb_lu);
 
 	INIT_WORK(&hpb->map_work, ufshpb_map_work_handler);
-	if (hpb->is_hcm)
+	if (hpb->is_hcm) {
 		INIT_WORK(&hpb->ufshpb_normalization_work,
 			  ufshpb_normalization_work_handler);
+		INIT_WORK(&hpb->ufshpb_lun_reset_work,
+			  ufshpb_reset_work_handler);
+	}
 
 	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
 			  sizeof(struct ufshpb_req), 0, 0, NULL);
@@ -2085,8 +2117,10 @@ static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
 
 static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
 {
-	if (hpb->is_hcm)
+	if (hpb->is_hcm) {
+		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
 		cancel_work_sync(&hpb->ufshpb_normalization_work);
+	}
 	cancel_work_sync(&hpb->map_work);
 }
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 13ec49ba260d..a3b85d2df224 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -119,6 +119,7 @@ struct ufshpb_region {
 	struct list_head list_lru_rgn;
 	unsigned long rgn_flags;
 #define RGN_FLAG_DIRTY 0
+#define RGN_FLAG_UPDATE 1
 
 	/* region reads - for host mode */
 	spinlock_t rgn_lock;
@@ -215,8 +216,10 @@ struct ufshpb_lu {
 	/* for selecting victim */
 	struct victim_select_info lru_info;
 	struct work_struct ufshpb_normalization_work;
+	struct work_struct ufshpb_lun_reset_work;
 	unsigned long work_data_bits;
 #define WORK_PENDING 0
+#define RESET_PENDING 1
 
 	/* pinned region information */
 	u32 lu_pinned_start;
-- 
2.25.1

[PATCH v3 7/9] scsi: ufshpb: Add "Cold" regions timer

[Avri Altman]

In order not to hang on to “cold” regions, we shall inactivate a
region that has no READ access for a predefined amount of time -
READ_TO_MS. For that purpose we shall monitor the active regions list,
polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
the region to the "to-be-inactivated" list, unless it is clean and did
not exhaust its READ_TO_EXPIRIES - another parameter.

All this does not apply to pinned regions.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 70 ++++++++++++++++++++++++++++++++++++++-
 drivers/scsi/ufs/ufshpb.h |  7 ++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 15755f677097..9a1c525204f7 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -18,6 +18,9 @@
 
 #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
 #define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
+#define READ_TO_MS 1000
+#define READ_TO_EXPIRIES 100
+#define POLLING_INTERVAL_MS 200
 
 /* memory management */
 static struct kmem_cache *ufshpb_mctx_cache;
@@ -1029,12 +1032,64 @@ static int ufshpb_check_srgns_issue_state(struct ufshpb_lu *hpb,
 	return 0;
 }
 
+static void ufshpb_read_to_handler(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct ufshpb_lu *hpb;
+	struct victim_select_info *lru_info;
+	struct ufshpb_region *rgn;
+	unsigned long flags;
+	LIST_HEAD(expired_list);
+
+	hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
+
+	if (test_and_set_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits))
+		return;
+
+	spin_lock_irqsave(&hpb->rgn_state_lock, flags);
+
+	lru_info = &hpb->lru_info;
+
+	list_for_each_entry(rgn, &lru_info->lh_lru_rgn, list_lru_rgn) {
+		bool timedout = ktime_after(ktime_get(), rgn->read_timeout);
+
+		if (timedout) {
+			rgn->read_timeout_expiries--;
+			if (is_rgn_dirty(rgn) ||
+			    rgn->read_timeout_expiries == 0)
+				list_add(&rgn->list_expired_rgn, &expired_list);
+			else
+				rgn->read_timeout = ktime_add_ms(ktime_get(),
+							 READ_TO_MS);
+		}
+	}
+
+	spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+
+	list_for_each_entry(rgn, &expired_list, list_expired_rgn) {
+		list_del_init(&rgn->list_expired_rgn);
+		spin_lock_irqsave(&hpb->rsp_list_lock, flags);
+		ufshpb_update_inactive_info(hpb, rgn->rgn_idx);
+		hpb->stats.rb_inactive_cnt++;
+		spin_unlock_irqrestore(&hpb->rsp_list_lock, flags);
+	}
+
+	clear_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits);
+
+	schedule_delayed_work(&hpb->ufshpb_read_to_work,
+			      msecs_to_jiffies(POLLING_INTERVAL_MS));
+}
+
 static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
-				       struct ufshpb_region *rgn)
+				struct ufshpb_region *rgn)
 {
 	rgn->rgn_state = HPB_RGN_ACTIVE;
 	list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
 	atomic_inc(&lru_info->active_cnt);
+	if (rgn->hpb->is_hcm) {
+		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
+		rgn->read_timeout_expiries = READ_TO_EXPIRIES;
+	}
 }
 
 static void ufshpb_hit_lru_info(struct victim_select_info *lru_info,
@@ -1778,6 +1833,7 @@ static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 
 		INIT_LIST_HEAD(&rgn->list_inact_rgn);
 		INIT_LIST_HEAD(&rgn->list_lru_rgn);
+		INIT_LIST_HEAD(&rgn->list_expired_rgn);
 
 		if (rgn_idx == hpb->rgns_per_lu - 1) {
 			srgn_cnt = ((hpb->srgns_per_lu - 1) %
@@ -1799,6 +1855,7 @@ static int ufshpb_alloc_region_tbl(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 		}
 
 		rgn->rgn_flags = 0;
+		rgn->hpb = hpb;
 	}
 
 	return 0;
@@ -2017,6 +2074,8 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 			  ufshpb_normalization_work_handler);
 		INIT_WORK(&hpb->ufshpb_lun_reset_work,
 			  ufshpb_reset_work_handler);
+		INIT_DELAYED_WORK(&hpb->ufshpb_read_to_work,
+				  ufshpb_read_to_handler);
 	}
 
 	hpb->map_req_cache = kmem_cache_create("ufshpb_req_cache",
@@ -2051,6 +2110,10 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 	ufshpb_stat_init(hpb);
 	ufshpb_param_init(hpb);
 
+	if (hpb->is_hcm)
+		schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				      msecs_to_jiffies(POLLING_INTERVAL_MS));
+
 	return 0;
 
 release_pre_req_mempool:
@@ -2118,6 +2181,7 @@ static void ufshpb_discard_rsp_lists(struct ufshpb_lu *hpb)
 static void ufshpb_cancel_jobs(struct ufshpb_lu *hpb)
 {
 	if (hpb->is_hcm) {
+		cancel_delayed_work_sync(&hpb->ufshpb_read_to_work);
 		cancel_work_sync(&hpb->ufshpb_lun_reset_work);
 		cancel_work_sync(&hpb->ufshpb_normalization_work);
 	}
@@ -2228,6 +2292,10 @@ void ufshpb_resume(struct ufs_hba *hba)
 			continue;
 		ufshpb_set_state(hpb, HPB_PRESENT);
 		ufshpb_kick_map_work(hpb);
+		if (hpb->is_hcm)
+			schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				msecs_to_jiffies(POLLING_INTERVAL_MS));
+
 	}
 }
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index a3b85d2df224..75093271d12b 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -107,6 +107,7 @@ struct ufshpb_subregion {
 };
 
 struct ufshpb_region {
+	struct ufshpb_lu *hpb;
 	struct ufshpb_subregion *srgn_tbl;
 	enum HPB_RGN_STATE rgn_state;
 	int rgn_idx;
@@ -124,6 +125,10 @@ struct ufshpb_region {
 	/* region reads - for host mode */
 	spinlock_t rgn_lock;
 	unsigned int reads;
+	/* region "cold" timer - for host mode */
+	ktime_t read_timeout;
+	unsigned int read_timeout_expiries;
+	struct list_head list_expired_rgn;
 };
 
 #define for_each_sub_region(rgn, i, srgn)				\
@@ -217,9 +222,11 @@ struct ufshpb_lu {
 	struct victim_select_info lru_info;
 	struct work_struct ufshpb_normalization_work;
 	struct work_struct ufshpb_lun_reset_work;
+	struct delayed_work ufshpb_read_to_work;
 	unsigned long work_data_bits;
 #define WORK_PENDING 0
 #define RESET_PENDING 1
+#define TIMEOUT_WORK_PENDING 2
 
 	/* pinned region information */
 	u32 lu_pinned_start;
-- 
2.25.1

[PATCH v3 8/9] scsi: ufshpb: Add support for host control mode

[Avri Altman]

Support devices that report they are using host control mode.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 drivers/scsi/ufs/ufshpb.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 9a1c525204f7..2c0f63a828ca 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -2523,12 +2523,6 @@ void ufshpb_get_dev_info(struct ufs_hba *hba, u8 *desc_buf)
 	u32 max_hpb_sigle_cmd = 0;
 
 	hpb_dev_info->control_mode = desc_buf[DEVICE_DESC_PARAM_HPB_CONTROL];
-	if (hpb_dev_info->control_mode == HPB_HOST_CONTROL) {
-		dev_err(hba->dev, "%s: host control mode is not supported.\n",
-			__func__);
-		hpb_dev_info->hpb_disabled = true;
-		return;
-	}
 
 	version = get_unaligned_be16(desc_buf + DEVICE_DESC_PARAM_HPB_VER);
 	if (version != HPB_SUPPORT_VERSION) {
-- 
2.25.1

[PATCH v3 9/9] scsi: ufshpb: Make host mode parameters configurable

[Avri Altman]

We can make use of this commit, to elaborate some more of the host
control mode logic, explaining what role play each and every variable.

While at it, allow those parameters to be configurable.

Signed-off-by: Avri Altman <avri.altman@wdc.com>
---
 Documentation/ABI/testing/sysfs-driver-ufs |  68 ++++++
 drivers/scsi/ufs/ufshpb.c                  | 254 +++++++++++++++++++--
 drivers/scsi/ufs/ufshpb.h                  |  18 ++
 3 files changed, 326 insertions(+), 14 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
index 0017eaf89cbe..1d72201c4953 100644
--- a/Documentation/ABI/testing/sysfs-driver-ufs
+++ b/Documentation/ABI/testing/sysfs-driver-ufs
@@ -1322,3 +1322,71 @@ Description:	This entry shows the maximum HPB data size for using single HPB
 		===  ========
 
 		The file is read only.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	In host control mode, reads are the major source of activation
+		trials.  once this threshold hs met, the region is added to the
+		"to-be-activated" list.  Since we reset the read counter upon
+		write, this include sending a rb command updating the region
+		ppn as well.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/normalization_factor
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	In host control mode, We think of the regions as "buckets".
+		Those buckets are being filled with reads, and emptied on write.
+		We use entries_per_srgn - the amount of blocks in a subregion as
+		our bucket size.  This applies because HPB1.0 only concern a
+		single-block reads.  Once the bucket size is crossed, we trigger
+		a normalization work - not only to avoid overflow, but mainly
+		because we want to keep those counters normalized, as we are
+		using those reads as a comparative score, to make various decisions.
+		The normalization is dividing (shift right) the read counter by
+		the normalization_factor. If during consecutive normalizations
+		an active region has exhaust its reads - inactivate it.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_enter
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	Region deactivation is often due to the fact that eviction took
+		place: a region become active on the expense of another. This is
+		happening when the max-active-regions limit has crossed.
+		In host mode, eviction is considered an extreme measure. We
+		want to verify that the entering region has enough reads, and
+		the exiting region has much less reads.  eviction_thld_enter is
+		the min reads that a region must have in order to be considered
+		as a candidate to evict other region.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_exit
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	same as above for the exiting region. A region is consider to
+		be a candidate to be evicted, only if it has less reads than
+		eviction_thld_exit.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_ms
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	In order not to hang on to “cold” regions, we shall inactivate
+		a region that has no READ access for a predefined amount of
+		time - read_timeout_ms. If read_timeout_ms has expired, and the
+		region is dirty - it is less likely that we can make any use of
+		HPB-READing it.  So we inactivate it.  Still, deactivation has
+		its overhead, and we may still benefit from HPB-READing this
+		region if it is clean - see read_timeout_expiries.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_expiries
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	if the region read timeout has expired, but the region is clean,
+		just re-wind its timer for another spin.  Do that as long as it
+		is clean and did not exhaust its read_timeout_expiries threshold.
+
+What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/timeout_polling_interval_ms
+Date:		February 2021
+Contact:	Avri Altman <avri.altman@wdc.com>
+Description:	the frequency in which the delayed worker that checks the
+		read_timeouts is awaken.
+>>>>>>> ef6bf08e666d... scsi: ufshpb: Make host mode parameters configurable
diff --git a/drivers/scsi/ufs/ufshpb.c b/drivers/scsi/ufs/ufshpb.c
index 2c0f63a828ca..44069974f627 100644
--- a/drivers/scsi/ufs/ufshpb.c
+++ b/drivers/scsi/ufs/ufshpb.c
@@ -17,7 +17,6 @@
 #include "../sd.h"
 
 #define ACTIVATION_THRESHOLD 4 /* 4 IOs */
-#define EVICTION_THRESHOLD (ACTIVATION_THRESHOLD << 6) /* 256 IOs */
 #define READ_TO_MS 1000
 #define READ_TO_EXPIRIES 100
 #define POLLING_INTERVAL_MS 200
@@ -658,7 +657,7 @@ int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 		 */
 		spin_lock_irqsave(&rgn->rgn_lock, flags);
 		rgn->reads++;
-		if (rgn->reads == ACTIVATION_THRESHOLD)
+		if (rgn->reads == hpb->params.activation_thld)
 			activate = true;
 		spin_unlock_irqrestore(&rgn->rgn_lock, flags);
 		if (activate ||
@@ -1039,6 +1038,7 @@ static void ufshpb_read_to_handler(struct work_struct *work)
 	struct victim_select_info *lru_info;
 	struct ufshpb_region *rgn;
 	unsigned long flags;
+	unsigned int poll;
 	LIST_HEAD(expired_list);
 
 	hpb = container_of(dwork, struct ufshpb_lu, ufshpb_read_to_work);
@@ -1060,7 +1060,7 @@ static void ufshpb_read_to_handler(struct work_struct *work)
 				list_add(&rgn->list_expired_rgn, &expired_list);
 			else
 				rgn->read_timeout = ktime_add_ms(ktime_get(),
-							 READ_TO_MS);
+						hpb->params.read_timeout_ms);
 		}
 	}
 
@@ -1076,8 +1076,9 @@ static void ufshpb_read_to_handler(struct work_struct *work)
 
 	clear_bit(TIMEOUT_WORK_PENDING, &hpb->work_data_bits);
 
+	poll = hpb->params.timeout_polling_interval_ms;
 	schedule_delayed_work(&hpb->ufshpb_read_to_work,
-			      msecs_to_jiffies(POLLING_INTERVAL_MS));
+			      msecs_to_jiffies(poll));
 }
 
 static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
@@ -1087,8 +1088,11 @@ static void ufshpb_add_lru_info(struct victim_select_info *lru_info,
 	list_add_tail(&rgn->list_lru_rgn, &lru_info->lh_lru_rgn);
 	atomic_inc(&lru_info->active_cnt);
 	if (rgn->hpb->is_hcm) {
-		rgn->read_timeout = ktime_add_ms(ktime_get(), READ_TO_MS);
-		rgn->read_timeout_expiries = READ_TO_EXPIRIES;
+		rgn->read_timeout =
+			ktime_add_ms(ktime_get(),
+				     rgn->hpb->params.read_timeout_ms);
+		rgn->read_timeout_expiries =
+			rgn->hpb->params.read_timeout_expiries;
 	}
 }
 
@@ -1112,7 +1116,8 @@ static struct ufshpb_region *ufshpb_victim_lru_info(struct ufshpb_lu *hpb)
 		 * in host control mode, verify that the exiting region
 		 * has less reads
 		 */
-		if (hpb->is_hcm && rgn->reads > (EVICTION_THRESHOLD >> 1))
+		if (hpb->is_hcm &&
+		    rgn->reads > hpb->params.eviction_thld_exit)
 			continue;
 
 		victim_rgn = rgn;
@@ -1326,7 +1331,8 @@ static int ufshpb_add_region(struct ufshpb_lu *hpb, struct ufshpb_region *rgn)
 			 * in host control mode, verify that the entering
 			 * region has enough reads
 			 */
-			if (hpb->is_hcm && rgn->reads < EVICTION_THRESHOLD) {
+			if (hpb->is_hcm &&
+			    rgn->reads < hpb->params.eviction_thld_enter) {
 				ret = -EACCES;
 				goto out;
 			}
@@ -1646,8 +1652,10 @@ static void ufshpb_normalization_work_handler(struct work_struct *work)
 {
 	struct ufshpb_lu *hpb;
 	int rgn_idx;
+	u8 factor;
 
 	hpb = container_of(work, struct ufshpb_lu, ufshpb_normalization_work);
+	factor = hpb->params.normalization_factor;
 
 	for (rgn_idx = 0; rgn_idx < hpb->rgns_per_lu; rgn_idx++) {
 		struct ufshpb_region *rgn = hpb->rgn_tbl + rgn_idx;
@@ -1656,7 +1664,7 @@ static void ufshpb_normalization_work_handler(struct work_struct *work)
 			unsigned long flags;
 
 			spin_lock_irqsave(&rgn->rgn_lock, flags);
-			rgn->reads = (rgn->reads >> 1);
+			rgn->reads = (rgn->reads >> factor);
 			spin_unlock_irqrestore(&rgn->rgn_lock, flags);
 		}
 
@@ -1979,8 +1987,217 @@ requeue_timeout_ms_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RW(requeue_timeout_ms);
 
+ufshpb_sysfs_param_show_func(activation_thld);
+static ssize_t
+activation_thld_store(struct device *dev, struct device_attribute *attr,
+		      const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= 0)
+		return -EINVAL;
+
+	hpb->params.activation_thld = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(activation_thld);
+
+ufshpb_sysfs_param_show_func(normalization_factor);
+static ssize_t
+normalization_factor_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= 0 || val > ilog2(hpb->entries_per_srgn))
+		return -EINVAL;
+
+	hpb->params.normalization_factor = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(normalization_factor);
+
+ufshpb_sysfs_param_show_func(eviction_thld_enter);
+static ssize_t
+eviction_thld_enter_store(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= hpb->params.eviction_thld_exit)
+		return -EINVAL;
+
+	hpb->params.eviction_thld_enter = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(eviction_thld_enter);
+
+ufshpb_sysfs_param_show_func(eviction_thld_exit);
+static ssize_t
+eviction_thld_exit_store(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= hpb->params.activation_thld)
+		return -EINVAL;
+
+	hpb->params.eviction_thld_exit = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(eviction_thld_exit);
+
+ufshpb_sysfs_param_show_func(read_timeout_ms);
+static ssize_t
+read_timeout_ms_store(struct device *dev, struct device_attribute *attr,
+		      const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= 0)
+		return -EINVAL;
+
+	hpb->params.read_timeout_ms = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(read_timeout_ms);
+
+ufshpb_sysfs_param_show_func(read_timeout_expiries);
+static ssize_t
+read_timeout_expiries_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= 0)
+		return -EINVAL;
+
+	hpb->params.read_timeout_expiries = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(read_timeout_expiries);
+
+ufshpb_sysfs_param_show_func(timeout_polling_interval_ms);
+static ssize_t
+timeout_polling_interval_ms_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct ufshpb_lu *hpb = ufshpb_get_hpb_data(sdev);
+	int val;
+
+	if (!hpb)
+		return -ENODEV;
+
+	if (!hpb->is_hcm)
+		return -EOPNOTSUPP;
+
+	if (kstrtouint(buf, 0, &val))
+		return -EINVAL;
+
+	if (val <= 0)
+		return -EINVAL;
+
+	hpb->params.timeout_polling_interval_ms = val;
+
+	return count;
+}
+static DEVICE_ATTR_RW(timeout_polling_interval_ms);
+
+static void ufshpb_hcm_param_init(struct ufshpb_lu *hpb)
+{
+	hpb->params.activation_thld = ACTIVATION_THRESHOLD;
+	hpb->params.normalization_factor = 1;
+	hpb->params.eviction_thld_enter = (ACTIVATION_THRESHOLD << 6);
+	hpb->params.eviction_thld_exit = (ACTIVATION_THRESHOLD << 5);
+	hpb->params.read_timeout_ms = READ_TO_MS;
+	hpb->params.read_timeout_expiries = READ_TO_EXPIRIES;
+	hpb->params.timeout_polling_interval_ms = POLLING_INTERVAL_MS;
+}
+
 static struct attribute *hpb_dev_param_attrs[] = {
 	&dev_attr_requeue_timeout_ms.attr,
+	&dev_attr_activation_thld.attr,
+	&dev_attr_normalization_factor.attr,
+	&dev_attr_eviction_thld_enter.attr,
+	&dev_attr_eviction_thld_exit.attr,
+	&dev_attr_read_timeout_ms.attr,
+	&dev_attr_read_timeout_expiries.attr,
+	&dev_attr_timeout_polling_interval_ms.attr,
+	NULL,
 };
 
 struct attribute_group ufs_sysfs_hpb_param_group = {
@@ -2054,6 +2271,8 @@ static void ufshpb_stat_init(struct ufshpb_lu *hpb)
 static void ufshpb_param_init(struct ufshpb_lu *hpb)
 {
 	hpb->params.requeue_timeout_ms = HPB_REQUEUE_TIME_MS;
+	if (hpb->is_hcm)
+		ufshpb_hcm_param_init(hpb);
 }
 
 static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
@@ -2110,9 +2329,13 @@ static int ufshpb_lu_hpb_init(struct ufs_hba *hba, struct ufshpb_lu *hpb)
 	ufshpb_stat_init(hpb);
 	ufshpb_param_init(hpb);
 
-	if (hpb->is_hcm)
+	if (hpb->is_hcm) {
+		unsigned int poll;
+
+		poll = hpb->params.timeout_polling_interval_ms;
 		schedule_delayed_work(&hpb->ufshpb_read_to_work,
-				      msecs_to_jiffies(POLLING_INTERVAL_MS));
+				      msecs_to_jiffies(poll));
+	}
 
 	return 0;
 
@@ -2292,10 +2515,13 @@ void ufshpb_resume(struct ufs_hba *hba)
 			continue;
 		ufshpb_set_state(hpb, HPB_PRESENT);
 		ufshpb_kick_map_work(hpb);
-		if (hpb->is_hcm)
-			schedule_delayed_work(&hpb->ufshpb_read_to_work,
-				msecs_to_jiffies(POLLING_INTERVAL_MS));
+		if (hpb->is_hcm) {
+			unsigned int poll =
+				hpb->params.timeout_polling_interval_ms;
 
+			schedule_delayed_work(&hpb->ufshpb_read_to_work,
+				msecs_to_jiffies(poll));
+		}
 	}
 }
 
diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 75093271d12b..bfb5eff9a66a 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h
@@ -178,8 +178,26 @@ struct victim_select_info {
 	atomic_t active_cnt;
 };
 
+/**
+ * ufshpb_params - ufs hpb parameters
+ * @requeue_timeout_ms - requeue threshold of wb command (0x2)
+ * @activation_thld - min reads [IOs] to activate/update a region
+ * @normalization_factor - shift right the region's reads
+ * @eviction_thld_enter - min reads [IOs] for the entering region in eviction
+ * @eviction_thld_exit - max reads [IOs] for the exiting region in eviction
+ * @read_timeout_ms - timeout [ms] from the last read IO to the region
+ * @read_timeout_expiries - amount of allowable timeout expireis
+ * @timeout_polling_interval_ms - frequency in which timeouts are checked
+ */
 struct ufshpb_params {
 	unsigned int requeue_timeout_ms;
+	unsigned int activation_thld;
+	unsigned int normalization_factor;
+	unsigned int eviction_thld_enter;
+	unsigned int eviction_thld_exit;
+	unsigned int read_timeout_ms;
+	unsigned int read_timeout_expiries;
+	unsigned int timeout_polling_interval_ms;
 };
 
 struct ufshpb_stats {
-- 
2.25.1

Re: [PATCH v3 9/9] scsi: ufshpb: Make host mode parameters configurable

[Greg KH]

On Thu, Feb 18, 2021 at 03:19:32PM +0200, Avri Altman wrote:
> We can make use of this commit, to elaborate some more of the host
> control mode logic, explaining what role play each and every variable.
> 
> While at it, allow those parameters to be configurable.
> 
> Signed-off-by: Avri Altman <avri.altman@wdc.com>
> ---
>  Documentation/ABI/testing/sysfs-driver-ufs |  68 ++++++
>  drivers/scsi/ufs/ufshpb.c                  | 254 +++++++++++++++++++--
>  drivers/scsi/ufs/ufshpb.h                  |  18 ++
>  3 files changed, 326 insertions(+), 14 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs
> index 0017eaf89cbe..1d72201c4953 100644
> --- a/Documentation/ABI/testing/sysfs-driver-ufs
> +++ b/Documentation/ABI/testing/sysfs-driver-ufs
> @@ -1322,3 +1322,71 @@ Description:	This entry shows the maximum HPB data size for using single HPB
>  		===  ========
>  
>  		The file is read only.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	In host control mode, reads are the major source of activation
> +		trials.  once this threshold hs met, the region is added to the
> +		"to-be-activated" list.  Since we reset the read counter upon
> +		write, this include sending a rb command updating the region
> +		ppn as well.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/normalization_factor
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	In host control mode, We think of the regions as "buckets".
> +		Those buckets are being filled with reads, and emptied on write.
> +		We use entries_per_srgn - the amount of blocks in a subregion as
> +		our bucket size.  This applies because HPB1.0 only concern a
> +		single-block reads.  Once the bucket size is crossed, we trigger
> +		a normalization work - not only to avoid overflow, but mainly
> +		because we want to keep those counters normalized, as we are
> +		using those reads as a comparative score, to make various decisions.
> +		The normalization is dividing (shift right) the read counter by
> +		the normalization_factor. If during consecutive normalizations
> +		an active region has exhaust its reads - inactivate it.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_enter
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	Region deactivation is often due to the fact that eviction took
> +		place: a region become active on the expense of another. This is
> +		happening when the max-active-regions limit has crossed.
> +		In host mode, eviction is considered an extreme measure. We
> +		want to verify that the entering region has enough reads, and
> +		the exiting region has much less reads.  eviction_thld_enter is
> +		the min reads that a region must have in order to be considered
> +		as a candidate to evict other region.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_exit
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	same as above for the exiting region. A region is consider to
> +		be a candidate to be evicted, only if it has less reads than
> +		eviction_thld_exit.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_ms
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	In order not to hang on to “cold” regions, we shall inactivate
> +		a region that has no READ access for a predefined amount of
> +		time - read_timeout_ms. If read_timeout_ms has expired, and the
> +		region is dirty - it is less likely that we can make any use of
> +		HPB-READing it.  So we inactivate it.  Still, deactivation has
> +		its overhead, and we may still benefit from HPB-READing this
> +		region if it is clean - see read_timeout_expiries.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_expiries
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	if the region read timeout has expired, but the region is clean,
> +		just re-wind its timer for another spin.  Do that as long as it
> +		is clean and did not exhaust its read_timeout_expiries threshold.
> +
> +What:		/sys/class/scsi_device/*/device/hpb_param_sysfs/timeout_polling_interval_ms
> +Date:		February 2021
> +Contact:	Avri Altman <avri.altman@wdc.com>
> +Description:	the frequency in which the delayed worker that checks the
> +		read_timeouts is awaken.
> +>>>>>>> ef6bf08e666d... scsi: ufshpb: Make host mode parameters configurable

Did you mean for this last line to be here?

RE: [PATCH v3 9/9] scsi: ufshpb: Make host mode parameters configurable

[Avri Altman]

> > +What:
> /sys/class/scsi_device/*/device/hpb_param_sysfs/timeout_polling_interval_ms
> > +Date:                February 2021
> > +Contact:     Avri Altman <avri.altman@wdc.com>
> > +Description: the frequency in which the delayed worker that checks the
> > +             read_timeouts is awaken.
> > +>>>>>>> ef6bf08e666d... scsi: ufshpb: Make host mode parameters
> configurable
> 
> Did you mean for this last line to be here?
Thanks. Done.