[PATCH v2 1/3] scsi: ufs: core: Remove redundant host_lock calls around UTMRLDBR.

[Avri Altman <avri.altman@xxxxxxx>]

There is no need to serialize single read/write calls to the host
controller registers. Remove the redundant host_lock calls that protect
access to the task management doorbell register: UTMRLDBR.

Signed-off-by: Avri Altman <avri.altman@xxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9e6d008f4ea4..29f1cd3375bd 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1245,11 +1245,13 @@ static bool ufshcd_is_devfreq_scaling_required(struct ufs_hba *hba,
 static u32 ufshcd_pending_cmds(struct ufs_hba *hba)
 {
 	const struct scsi_device *sdev;
+	unsigned long flags;
 	u32 pending = 0;
 
-	lockdep_assert_held(hba->host->host_lock);
+	spin_lock_irqsave(hba->host->host_lock, flags);
 	__shost_for_each_device(sdev, hba->host)
 		pending += sbitmap_weight(&sdev->budget_map);
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
 
 	return pending;
 }
@@ -1263,7 +1265,6 @@ static u32 ufshcd_pending_cmds(struct ufs_hba *hba)
 static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 					u64 wait_timeout_us)
 {
-	unsigned long flags;
 	int ret = 0;
 	u32 tm_doorbell;
 	u32 tr_pending;
@@ -1271,7 +1272,6 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 	ktime_t start;
 
 	ufshcd_hold(hba);
-	spin_lock_irqsave(hba->host->host_lock, flags);
 	/*
 	 * Wait for all the outstanding tasks/transfer requests.
 	 * Verify by checking the doorbell registers are clear.
@@ -1292,7 +1292,6 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 			break;
 		}
 
-		spin_unlock_irqrestore(hba->host->host_lock, flags);
 		io_schedule_timeout(msecs_to_jiffies(20));
 		if (ktime_to_us(ktime_sub(ktime_get(), start)) >
 		    wait_timeout_us) {
@@ -1304,7 +1303,6 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 			 */
 			do_last_check = true;
 		}
-		spin_lock_irqsave(hba->host->host_lock, flags);
 	} while (tm_doorbell || tr_pending);
 
 	if (timeout) {
@@ -1314,7 +1312,6 @@ static int ufshcd_wait_for_doorbell_clr(struct ufs_hba *hba,
 		ret = -EBUSY;
 	}
 out:
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	ufshcd_release(hba);
 	return ret;
 }
@@ -6877,13 +6874,13 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba, u32 intr_status)
  */
 static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
 {
-	unsigned long flags, pending, issued;
+	unsigned long flags;
+	unsigned long pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
+	unsigned long issued = hba->outstanding_tasks & ~pending;
 	irqreturn_t ret = IRQ_NONE;
 	int tag;
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
-	pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
-	issued = hba->outstanding_tasks & ~pending;
 	for_each_set_bit(tag, &issued, hba->nutmrs) {
 		struct request *req = hba->tmf_rqs[tag];
 		struct completion *c = req->end_io_data;
@@ -7065,12 +7062,13 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba,
 	memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
 	ufshcd_vops_setup_task_mgmt(hba, task_tag, tm_function);
 
-	/* send command to the controller */
 	__set_bit(task_tag, &hba->outstanding_tasks);
-	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TASK_REQ_DOOR_BELL);
 
 	spin_unlock_irqrestore(host->host_lock, flags);
 
+	/* send command to the controller */
+	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TASK_REQ_DOOR_BELL);
+
 	ufshcd_add_tm_upiu_trace(hba, task_tag, UFS_TM_SEND);
 
 	/* wait until the task management command is completed */
-- 
2.25.1