scsi: ufs: Change fDeviceInit busy wait

Currently, the UFS driver busy waits for fDeviceInit to be cleared. Provide
an upper bound and sleep between attempts instead of busy waiting.

Link: https://lore.kernel.org/r/1597053747-75171-1-git-send-email-kwmad.kim@samsung.comTested-by: Kiwoong Kim <kwmad.kim@samsung.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.c

@@ -74,6 +74,9 @@
 /* Default value of wait time before gating device ref clock */
 #define UFSHCD_REF_CLK_GATING_WAIT_US 0xFF /* microsecs */
 
+/* Polling time to wait for fDeviceInit */
+#define FDEVICEINIT_COMPL_TIMEOUT 1500 /* millisecs */
+
 #define ufshcd_toggle_vreg(_dev, _vreg, _on)				\
 	({                                                              \
 		int _ret;                                               \
@@ -4175,9 +4178,9 @@ EXPORT_SYMBOL_GPL(ufshcd_config_pwr_mode);
  */
 static int ufshcd_complete_dev_init(struct ufs_hba *hba)
 {
-	int i;
 	int err;
 	bool flag_res = true;
+	ktime_t timeout;
 
 	err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_SET_FLAG,
 		QUERY_FLAG_IDN_FDEVICEINIT, 0, NULL);
@@ -4188,20 +4191,26 @@ static int ufshcd_complete_dev_init(struct ufs_hba *hba)
 		goto out;
 	}
 
-	/* poll for max. 1000 iterations for fDeviceInit flag to clear */
-	for (i = 0; i < 1000 && !err && flag_res; i++)
-		err = ufshcd_query_flag_retry(hba, UPIU_QUERY_OPCODE_READ_FLAG,
-			QUERY_FLAG_IDN_FDEVICEINIT, 0, &flag_res);
+	/* Poll fDeviceInit flag to be cleared */
+	timeout = ktime_add_ms(ktime_get(), FDEVICEINIT_COMPL_TIMEOUT);
+	do {
+		err = ufshcd_query_flag(hba, UPIU_QUERY_OPCODE_READ_FLAG,
+					QUERY_FLAG_IDN_FDEVICEINIT, 0, &flag_res);
+		if (!flag_res)
+			break;
+		usleep_range(5000, 10000);
+	} while (ktime_before(ktime_get(), timeout));
 
-	if (err)
+	if (err) {
 		dev_err(hba->dev,
-			"%s reading fDeviceInit flag failed with error %d\n",
-			__func__, err);
-	else if (flag_res)
+				"%s reading fDeviceInit flag failed with error %d\n",
+				__func__, err);
+	} else if (flag_res) {
 		dev_err(hba->dev,
-			"%s fDeviceInit was not cleared by the device\n",
-			__func__);
-
+				"%s fDeviceInit was not cleared by the device\n",
+				__func__);
+		err = -EBUSY;
+	}
 out:
 	return err;
 }