quoted

+#define WORK_PENDING 0
+#define ACTIVATION_THRSHLD 4 /* 4 IOs */

Rather than fixing it with macro, how about using sysfs and make it
configurable?

Yes.
I will add a patch making all the logic configurable.
As all those are hpb-related parameters, I think module parameters are more adequate.

quoted

@@ -306,12 +325,39 @@ void ufshpb_prep(struct ufs_hba *hba, struct

ufshcd_lrb *lrbp)

quoted

              ufshpb_set_ppn_dirty(hpb, rgn_idx, srgn_idx, srgn_offset,
                               transfer_len);
              spin_unlock_irqrestore(&hpb->rgn_state_lock, flags);
+
+             if (ufshpb_mode == HPB_HOST_CONTROL)
+                     atomic64_set(&rgn->reads, 0);
+
              return;
      }

+     if (ufshpb_mode == HPB_HOST_CONTROL)
+             reads = atomic64_inc_return(&rgn->reads);
+
      if (!ufshpb_is_support_chunk(transfer_len))
              return; <- *this*

+     if (ufshpb_mode == HPB_HOST_CONTROL) {
+             /*
+              * in host control mode, reads are the main source for
+              * activation trials.
+              */
+             if (reads == ACTIVATION_THRSHLD) {

If the chunk size is not supported, we can not active this region
permanently. It may be returned before get this statement.

Yes.
I already noticed that replying to Greg.
Fixed that when I dropped the use of atomic variables.
 

quoted

diff --git a/drivers/scsi/ufs/ufshpb.h b/drivers/scsi/ufs/ufshpb.h
index 8a34b0f42754..b0e78728af38 100644
--- a/drivers/scsi/ufs/ufshpb.h
+++ b/drivers/scsi/ufs/ufshpb.h

@@ -115,6 +115,9 @@ struct ufshpb_region {
      /* below information is used by lru */
      struct list_head list_lru_rgn;
      unsigned long rgn_flags;
+
+     /* region reads - for host mode */
+     atomic64_t reads;

I think 32 bits are suitable, because it is normalized by worker on every
specific time.

Done.