scsi: ufs: rockchip,rk3576-ufshc: dt-bindings: Add new mphy reset item

[ Upstream commit bdce3a6 ]

Add the mphy reset property to the devicetree bindings for the Rockchip
RK3576 UFS host controller. The mphy reset signal is used to reset the
physical adapter. Resetting other components while leaving the mphy unreset
may occasionally prevent the UFS controller from successfully linking up
with the device.

This addresses an intermittent hardware bug where the UFS link fails to
establish under specific timing conditions with certain chips. While
difficult to reproduce initially, this issue was consistently observed in
downstream testing and requires explicit mphy reset control for full
stability.

Although this change increases the maxItems for resets and adds a new entry
(which technically alters the binding ABI), it does not break compatibility
for existing Linux systems. The driver uses
devm_reset_control_array_get_exclusive() to manage resets, allowing it to
function correctly with both older Device Trees (without the mphy entry)
and newer ones.

Fixes: d90e920 ("scsi: ufs: dt-bindings: Document Rockchip UFS host controller")
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/1773368467-109650-1-git-send-email-shawn.lin@rock-chips.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: shawn1221

Documentation/devicetree/bindings/ufs/rockchip,rk3576-ufshc.yaml

@@ -41,14 +41,15 @@ properties:
     maxItems: 1
 
   resets:
-    maxItems: 4
+    maxItems: 5
 
   reset-names:
     items:
       - const: biu
       - const: sys
       - const: ufs
       - const: grf
+      - const: mphy
 
   reset-gpios:
     maxItems: 1
@@ -98,8 +99,8 @@ examples:
             interrupts = <GIC_SPI 361 IRQ_TYPE_LEVEL_HIGH>;
             power-domains = <&power RK3576_PD_USB>;
             resets = <&cru SRST_A_UFS_BIU>, <&cru SRST_A_UFS_SYS>, <&cru SRST_A_UFS>,
-                     <&cru SRST_P_UFS_GRF>;
-            reset-names = "biu", "sys", "ufs", "grf";
+                     <&cru SRST_P_UFS_GRF>, <&cru SRST_MPHY_INIT>;
+            reset-names = "biu", "sys", "ufs", "grf", "mphy";
             reset-gpios = <&gpio4 RK_PD0 GPIO_ACTIVE_LOW>;
         };
     };