[PATCH v5 17/28] ufs: core: Rework the SCSI host queue depth calculation code

[Bart Van Assche <bvanassche@acm.org>]

Prepare for allocating the SCSI host earlier by making the SCSI host
queue depth independent of the queue depth supported by the UFS device.
This patch may increase the queue depth of the UFS SCSI host.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufs-mcq.c     | 20 +++++---------------
 drivers/ufs/core/ufshcd-priv.h |  2 +-
 drivers/ufs/core/ufshcd.c      | 17 +++++++++++++++--
 3 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
index 4eb4f1af7800..b99e482ad8da 100644
--- a/drivers/ufs/core/ufs-mcq.c
+++ b/drivers/ufs/core/ufs-mcq.c
@@ -130,17 +130,15 @@ unsigned int ufshcd_mcq_queue_cfg_addr(struct ufs_hba *hba)
 EXPORT_SYMBOL_GPL(ufshcd_mcq_queue_cfg_addr);
 
 /**
- * ufshcd_mcq_decide_queue_depth - decide the queue depth
+ * ufshcd_get_hba_mac - Maximum number of commands supported by the host
+ *	controller.
  * @hba: per adapter instance
  *
- * Return: queue-depth on success, non-zero on error
+ * Return: queue depth on success; negative upon error.
  *
- * MAC - Max. Active Command of the Host Controller (HC)
- * HC wouldn't send more than this commands to the device.
- * Calculates and adjusts the queue depth based on the depth
- * supported by the HC and ufs device.
+ * MAC = Maximum number of Active Commands supported by the Host Controller.
  */
-int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
+int ufshcd_get_hba_mac(struct ufs_hba *hba)
 {
 	int mac;
 
@@ -160,14 +158,6 @@ int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
 	if (mac < 0)
 		goto err;
 
-	WARN_ON_ONCE(!hba->dev_info.bqueuedepth);
-	/*
-	 * max. value of bqueuedepth = 256, mac is host dependent.
-	 * It is mandatory for UFS device to define bQueueDepth if
-	 * shared queuing architecture is enabled.
-	 */
-	return min_t(int, mac, hba->dev_info.bqueuedepth);
-
 err:
 	dev_err(hba->dev, "Failed to get mac, err=%d\n", mac);
 	return mac;
diff --git a/drivers/ufs/core/ufshcd-priv.h b/drivers/ufs/core/ufshcd-priv.h
index d0a2c963a27d..ec1bb818bc73 100644
--- a/drivers/ufs/core/ufshcd-priv.h
+++ b/drivers/ufs/core/ufshcd-priv.h
@@ -65,7 +65,7 @@ void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
 			  struct cq_entry *cqe);
 int ufshcd_mcq_init(struct ufs_hba *hba);
 void ufshcd_mcq_disable(struct ufs_hba *hba);
-int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba);
+int ufshcd_get_hba_mac(struct ufs_hba *hba);
 int ufshcd_mcq_memory_alloc(struct ufs_hba *hba);
 struct ufs_hw_queue *ufshcd_mcq_req_to_hwq(struct ufs_hba *hba,
 					   struct request *req);
diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 67607f2d10a2..419f05efd566 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8438,10 +8438,11 @@ static void ufs_init_rtc(struct ufs_hba *hba, u8 *desc_buf)
 
 static int ufs_get_device_desc(struct ufs_hba *hba)
 {
+	struct ufs_dev_info *dev_info = &hba->dev_info;
+	struct Scsi_Host *shost = hba->host;
 	int err;
 	u8 model_index;
 	u8 *desc_buf;
-	struct ufs_dev_info *dev_info = &hba->dev_info;
 
 	desc_buf = kzalloc(QUERY_DESC_MAX_SIZE, GFP_KERNEL);
 	if (!desc_buf) {
@@ -8469,6 +8470,18 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
 				      desc_buf[DEVICE_DESC_PARAM_SPEC_VER + 1];
 	dev_info->bqueuedepth = desc_buf[DEVICE_DESC_PARAM_Q_DPTH];
 
+	/*
+	 * According to the UFS standard, the UFS device queue depth
+	 * (bQueueDepth) must be in the range 1..255 if the shared queueing
+	 * architecture is supported. bQueueDepth is zero if the shared queueing
+	 * architecture is not supported.
+	 */
+	if (dev_info->bqueuedepth)
+		shost->cmd_per_lun = min(hba->nutrs, dev_info->bqueuedepth) -
+				     UFSHCD_NUM_RESERVED;
+	else
+		shost->cmd_per_lun = shost->can_queue;
+
 	dev_info->rtt_cap = desc_buf[DEVICE_DESC_PARAM_RTT_CAP];
 
 	dev_info->hid_sup = get_unaligned_be32(desc_buf +
@@ -8875,7 +8888,7 @@ static int ufshcd_alloc_mcq(struct ufs_hba *hba)
 	int ret;
 	int old_nutrs = hba->nutrs;
 
-	ret = ufshcd_mcq_decide_queue_depth(hba);
+	ret = ufshcd_get_hba_mac(hba);
 	if (ret < 0)
 		return ret;