scsi: ufs: ufs-mediatek: support linkoff state during suspend

If system suspend or runtime suspend mode is configured as linkoff state,
phy can be powered off and reference clock can be gated in MediaTek
Chipsets.

At the same time, remove redundant reference clock control in suspend and
resume callbacks because such control can be well-handled in setup_clocks
callback.

Link: https://lore.kernel.org/r/20200129105251.12466-3-stanley.chu@mediatek.comReviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -167,7 +167,7 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
 
 	switch (status) {
 	case PRE_CHANGE:
-		if (!on) {
+		if (!on && !ufshcd_is_link_active(hba)) {
 			ufs_mtk_setup_ref_clk(hba, on);
 			ret = phy_power_off(host->mphy);
 		}
@@ -437,10 +437,11 @@ static int ufs_mtk_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 		err = ufs_mtk_link_set_lpm(hba);
 		if (err)
 			return -EAGAIN;
-		phy_power_off(host->mphy);
-		ufs_mtk_setup_ref_clk(hba, false);
 	}
 
+	if (!ufshcd_is_link_active(hba))
+		phy_power_off(host->mphy);
+
 	return 0;
 }
 
@@ -449,9 +450,10 @@ static int ufs_mtk_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
 	int err;
 
-	if (ufshcd_is_link_hibern8(hba)) {
-		ufs_mtk_setup_ref_clk(hba, true);
+	if (!ufshcd_is_link_active(hba))
 		phy_power_on(host->mphy);
+
+	if (ufshcd_is_link_hibern8(hba)) {
 		err = ufs_mtk_link_set_hpm(hba);
 		if (err)
 			return err;