Rob Herring wrote:

On Wed, Jul 22, 2020 at 07:12:39PM -0700, Thinh Nguyen wrote:

quoted

According to USB 3.2 spec, a super-speed-plus device can operate at
gen2x2, gen2x1, or gen1x2. Introduce "num-lanes" and
"lane-speed-mantissa-gbps" properties for devices operating in
super-speed-plus. If the USB controller device supports multiple lanes
at different transfer rate, the user can specify the HW capability via
these properties.

Signed-off-by: Thinh Nguyen <redacted>
---
Changes in v2:
- Make "num-lanes" and "lane-speed-mantissa-gbps" common USB properties

  Documentation/devicetree/bindings/usb/generic.txt | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
index ba472e7aefc9..a8253da684af 100644
--- a/Documentation/devicetree/bindings/usb/generic.txt
+++ b/Documentation/devicetree/bindings/usb/generic.txt

@@ -7,6 +7,17 @@ Optional properties:
  			"low-speed". In case this isn't passed via DT, USB
  			controllers should default to their maximum HW
  			capability.
+ - num-lanes: tells USB controllers that we want to work up to a certain number
+			of lanes. Valid arguments are 1 or 2. Apply if the
+			maximum-speed is super-speed-plus. In case this isn't
+			passed via DT, the USB controllers should default to
+			their maximum HW capability.
+ - lane-speed-mantissa-gbps: tells USB controllers that we want the symmetric
+			lanes to operate up to a certain rate in Gbps. Valid
+			inputs are 5 or 10 (i.e. Gen 1/Gen 2 transfer rate).
+			Apply if the maximum-speed is super-speed-plus. In case
+			this isn't passed via DT, the USB controllers should
+			default to their maximum HW capability.

This still leaves 'maximum-speed = "super-speed-plus"' ambiguous. Fix
that please.

To put it another way, we already have one way to define USB speeds.
Don't define a new and different way that only covers a fraction of the
possibilities.

Then, we can just do away with the "num-lanes" property, and change it 
to something like this as you suggested?

diff --git a/Documentation/devicetree/bindings/usb/generic.txt 

b/Documentation/devicetree/bindings/usb/generic.txt
index ba472e7aefc9..8541b9571f2f 100644

--- a/Documentation/devicetree/bindings/usb/generic.txt
+++ b/Documentation/devicetree/bindings/usb/generic.txt

@@ -3,10 +3,13 @@ Generic USB Properties
  Optional properties:
   - maximum-speed: tells USB controllers we want to work up to a certain
                         speed. Valid arguments are "super-speed-plus",
-                       "super-speed", "high-speed", "full-speed" and
-                       "low-speed". In case this isn't passed via DT, USB
-                       controllers should default to their maximum HW
-                       capability.
+                       "super-speed-plus-gen2x2", 

"super-speed-plus-gen2x1",
+                       "super-speed-plus-gen1x2", "super-speed", 
"high-speed",
+                       "full-speed" and "low-speed". In case this isn't 
passed
+                       via DT, USB controllers should default to their 
maximum
+                       HW capability. Similarly, if the argument is
+                       "super-speed-plus", USB controllers should 
default to
+                       their maximum transfer rate and number of lanes.
   - dr_mode: tells Dual-Role USB controllers that we want to work on a
                         particular mode. Valid arguments are "host",
                         "peripheral" and "otg". In case this attribute 
isn't


Is that ok?

BR,
Thinh