scsi: ufs: add retries for hibern8 enter

If hibern8 enter command fails then UFS link state may be unknown which
may result into timeout of all the commands issued after failure.

This change does 2 things (for pre-defined number of retry counts) after
hibern8 enter failure:

1. Recovers the UFS link to active state

2. If link is recovered to active state, tries to put the UFS link in
   hibern8 enter again until retry count expires.
Reviewed-by: Gilad Broner <gbroner@codeaurora.org>
Reviewed-by: Dolev Raviv <draviv@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.c

@@ -74,6 +74,9 @@
 /* maximum number of link-startup retries */
 #define DME_LINKSTARTUP_RETRIES 3
 
+/* Maximum retries for Hibern8 enter */
+#define UIC_HIBERN8_ENTER_RETRIES 3
+
 /* maximum number of reset retries before giving up */
 #define MAX_HOST_RESET_RETRIES 5
 
@@ -2387,13 +2390,32 @@ static int ufshcd_uic_change_pwr_mode(struct ufs_hba *hba, u8 mode)
 	return ret;
 }
 
-static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
+static int __ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
 {
+	int ret;
 	struct uic_command uic_cmd = {0};
 
 	uic_cmd.command = UIC_CMD_DME_HIBER_ENTER;
+	ret = ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
+
+	if (ret)
+		dev_err(hba->dev, "%s: hibern8 enter failed. ret = %d\n",
+			__func__, ret);
+
+	return ret;
+}
+
+static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba)
+{
+	int ret = 0, retries;
 
-	return ufshcd_uic_pwr_ctrl(hba, &uic_cmd);
+	for (retries = UIC_HIBERN8_ENTER_RETRIES; retries > 0; retries--) {
+		ret = __ufshcd_uic_hibern8_enter(hba);
+		if (!ret || ret == -ENOLINK)
+			goto out;
+	}
+out:
+	return ret;
 }
 
 static int ufshcd_uic_hibern8_exit(struct ufs_hba *hba)