scsi: ufs: ufshpb: Properly handle max-single-cmd

The spec recommends that for transfer length larger than the max-single-cmd
attribute (bMAX_DATA_SIZE_FOR_HPB_SINGLE_CMD) it is possible to couple
pre-requests with the HPB-READ command.  Being a recommendation, using
pre-requests can be perceived merely as a means of optimization.  A common
practice was to send pre-requests for chunks within some interval, and
leave the READ10 untouched if larger.

Now that the pre-request flows have been removed, all the commands are
single commands.  Properly handle this attribute and do not send HPB-READ
for transfer lengths larger than max-single-cmd.

[mkp: resolve conflict]

Fixes: 09d9e4d ("scsi: ufs: ufshpb: Remove HPB2.0 flows")
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Daejun Park <[email protected]>
Signed-off-by: Avri Altman <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

drivers/scsi/ufs/ufshpb.c

@@ -394,8 +394,6 @@ int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
 	if (!ufshpb_is_supported_chunk(hpb, transfer_len))
 		return 0;
 
-	WARN_ON_ONCE(transfer_len > HPB_MULTI_CHUNK_HIGH);
-
 	if (hpb->is_hcm) {
 		/*
 		 * in host control mode, reads are the main source for
@@ -1572,7 +1570,7 @@ static void ufshpb_lu_parameter_init(struct ufs_hba *hba,
 	if (ufshpb_is_legacy(hba))
 		hpb->pre_req_max_tr_len = HPB_LEGACY_CHUNK_HIGH;
 	else
-		hpb->pre_req_max_tr_len = HPB_MULTI_CHUNK_HIGH;
+		hpb->pre_req_max_tr_len = hpb_dev_info->max_hpb_single_cmd;
 
 	hpb->lu_pinned_start = hpb_lu_info->pinned_start;
 	hpb->lu_pinned_end = hpb_lu_info->num_pinned ?
@@ -2582,7 +2580,7 @@ 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;
-	u32 max_hpb_single_cmd = HPB_MULTI_CHUNK_LOW;
+	int max_single_cmd;
 
 	hpb_dev_info->control_mode = desc_buf[DEVICE_DESC_PARAM_HPB_CONTROL];
 
@@ -2598,18 +2596,22 @@ void ufshpb_get_dev_info(struct ufs_hba *hba, u8 *desc_buf)
 	if (version == HPB_SUPPORT_LEGACY_VERSION)
 		hpb_dev_info->is_legacy = true;
 
-	ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
-		QUERY_ATTR_IDN_MAX_HPB_SINGLE_CMD, 0, 0, &max_hpb_single_cmd);
-	if (ret)
-		dev_err(hba->dev, "%s: idn: read max size of single hpb cmd query request failed",
-			__func__);
-	hpb_dev_info->max_hpb_single_cmd = max_hpb_single_cmd;
-
 	/*
 	 * Get the number of user logical unit to check whether all
 	 * scsi_device finish initialization
 	 */
 	hpb_dev_info->num_lu = desc_buf[DEVICE_DESC_PARAM_NUM_LU];
+
+	if (hpb_dev_info->is_legacy)
+		return;
+
+	ret = ufshcd_query_attr_retry(hba, UPIU_QUERY_OPCODE_READ_ATTR,
+		QUERY_ATTR_IDN_MAX_HPB_SINGLE_CMD, 0, 0, &max_single_cmd);
+
+	if (ret)
+		hpb_dev_info->max_hpb_single_cmd = HPB_LEGACY_CHUNK_HIGH;
+	else
+		hpb_dev_info->max_hpb_single_cmd = min(max_single_cmd + 1, HPB_MULTI_CHUNK_HIGH);
 }
 
 void ufshpb_init(struct ufs_hba *hba)

drivers/scsi/ufs/ufshpb.h

@@ -31,7 +31,6 @@
 
 /* hpb support chunk size */
 #define HPB_LEGACY_CHUNK_HIGH			1
-#define HPB_MULTI_CHUNK_LOW			7
 #define HPB_MULTI_CHUNK_HIGH			255
 
 /* hpb vender defined opcode */