Re: [RFC 1/2] dt-bindings: usb: dwc3: Add support for multiport related properties

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On 5/23/2022 5:55 PM, Rob Herring wrote:
On Thu, May 19, 2022 at 06:04:54PM +0530, Harsh Agarwal wrote:
Added support for multiport, mport, num-ssphy and num-hsphy
properties. These properties are used to support devices having
a multiport controller.

Signed-off-by: Harsh Agarwal <quic_harshq@xxxxxxxxxxx>
---
  .../devicetree/bindings/usb/snps,dwc3.yaml         | 55 ++++++++++++++++++++++
  1 file changed, 55 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
index f4471f8..39c61483 100644
--- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
+++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
@@ -341,6 +341,35 @@ properties:
        This port is used with the 'usb-role-switch' property  to connect the
        dwc3 to type C connector.
+ multiport:
+    description:
+      If a single USB controller supports multiple ports, then it's referred to as
+      a multiport controller. Each port of the multiport controller can support
+      either High Speed or Super Speed or both and have their own PHY phandles. Each
+      port is represented by "mport" node and all the "mport" nodes are grouped
+      together inside the "multiport" node where individual "mport" node defines the
+      PHYs supported by that port.
+    required:
+      - mport
+
+  num-hsphy:
+    description: Total number of HS-PHYs defined by the multiport controller.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  num-ssphy:
+    description: Total number of SS-PHYs defined by the multiport controller.
+    $ref: /schemas/types.yaml#/definitions/uint32
These seem redundant. Can't you count ports/phys?

Counting ports will not suffice as there could be devices which has different numbers of HS and SS PHYs. Consider a case like a Quadport multiport controller where we have the 1st & 2nd port supporting SS and 3rd & 4th port supporting HS only. So we would need the proper number
of HS and SS PHYs.
Currently in the RFC v2 we are calculating the exact number of PHYS supported by each port
by counting the phandles we have defined.


+
+  mport:
+    description: Each mport node represents one port of the multiport controller.
+    patternProperties: "^mport@[0-9a-f]+$"
Think about how the USB device binding fits into this. A hub vs.
multiple root ports doesn't seem much different.
A hub will have multiple ports but only one HS and SS PHYs at the root port supporting it. With Multiport Controller, each port will have its own PHY [whether HS only or both HS & SS]

Rob



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