[PATCH 1/3] dt-bindings: usb: mtk-xhci: add a property for Gen1 isoc-in transfer issue

[Chunfeng Yun]

For Gen1 isoc-in endpoint on controller before about SSUSB IPM v1.6.0, it
still send out unexpected ACK after receiving a short packet in burst
transfer, this will cause an exception on connected device, specially for
a 4k camera.
Add a quirk property "mediatek,rxfifo-depth" to work around this hardware
issue;
The side-effect is that may cause performance drop about 10%, including
bulk transfer.

Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
---
 .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml     | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
index e9644e333d78..b8ed68574ba4 100644
--- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
+++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
@@ -124,6 +124,16 @@ properties:
       defined in the xHCI spec on MTK's controller.
     default: 5000
 
+  mediatek,rxfifo-depth:
+    description:
+      It is a quirk flag used to work around Gen1 isoc-in endpoint transfer
+      issue that still send out unexpected ACK after device finish the burst
+      transfer with a short packet and cause an exception, specially on a 4K
+      camera device, it happens on controller before about IPM v1.6.0; the
+      side-effect is that may cause performance drop about 10%, include bulk
+      transfer.
+    type: boolean
+
   # the following properties are only used for case 1
   wakeup-source:
     description: enable USB remote wakeup, see power/wakeup-source.txt
-- 
2.25.1