Re: [PATCH v6 02/10] scsi: ufshpb: Add host control mode support to rsp_upiu

[Zang Leigang <zangleigang@hisilicon.com>]

On Mon, Mar 22, 2021 at 10:10:36AM +0200, Avri Altman wrote:
> 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 fb10afcbb49f..d4f0bb6d8fa1 100644
> --- a/drivers/scsi/ufs/ufshpb.c
> +++ b/drivers/scsi/ufs/ufshpb.c
> @@ -166,6 +166,8 @@ 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);
> @@ -235,6 +237,11 @@ 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)
> @@ -713,6 +720,7 @@ 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;
>  
>  	if (!srgn->mctx) {
> @@ -726,6 +734,10 @@ 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;
>  }
>  
> @@ -1245,6 +1257,18 @@ 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;
> +		}
> +

Hi Avri, host control mode also need the recommendations from device,
because the bkops would make the ppn invalid, is that right?

>  		dev_dbg(&hpb->sdev_ufs_lu->sdev_dev,
>  			"activate(%d) region %d - %d\n", i, rgn_i, srgn_i);
>  
> @@ -1252,7 +1276,6 @@ 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 */
> @@ -1263,6 +1286,14 @@ 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,
> @@ -1287,6 +1318,7 @@ 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 7df30340386a..032672114881 100644
> --- a/drivers/scsi/ufs/ufshpb.h
> +++ b/drivers/scsi/ufs/ufshpb.h
> @@ -121,6 +121,8 @@ 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
>