Re: [PATCH 1/2] dt-bindings: usb: xhci: add xhci-no-soft-retry-quirk

[Matt Eaton]

On Fri, Aug 28, 2026 at 3:53 PM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
>
> On 28/08/2026 15:18, Matt Eaton wrote:
> > On Fri, Aug 28, 2026 at 2:39 PM Krzysztof Kozlowski <krzk@xxxxxxxxxx> wrote:
> >>
> >> On 28/08/2026 14:37, Matt Eaton via B4 Relay wrote:
> >>> From: Matt Eaton <linux@xxxxxxxxxxxxxx>
> >>>
> >>> Document the xhci-no-soft-retry-quirk property, added in the
> >>> following patch.
> >>>
> >>> snps,dwc3-common.yaml refs usb-xhci.yaml for every dr_mode other than
> >>> peripheral, so a host-mode dwc3 node inherits it and dt_binding_check
> >>> accepts it there.
> >>
> >> I do not understand how this sentence is relevant. Please describe the
> >> hardware needing this.
> >
> > I came across this while porting the UniFi Travel Router (IPQ4018),
> > the stock Qualcomm kernel is 4.4.60 which predates the soft retry
> > code. The command ring hangs if you disconnect the device while it's
> > transmitting. Reproducible consistently when using USB to tether to a
> > phone.
> >
> >>>
> >>> Signed-off-by: Matt Eaton <linux@xxxxxxxxxxxxxx>
> >>> ---
> >>>  Documentation/devicetree/bindings/usb/usb-xhci.yaml | 4 ++++
> >>>  1 file changed, 4 insertions(+)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.yaml b/Documentation/devicetree/bindings/usb/usb-xhci.yaml
> >>> index 4238ae896ef6..5d67a41658f7 100644
> >>> --- a/Documentation/devicetree/bindings/usb/usb-xhci.yaml
> >>> +++ b/Documentation/devicetree/bindings/usb/usb-xhci.yaml
> >>> @@ -25,6 +25,10 @@ properties:
> >>>      description: Set if the controller has broken port disable mechanism
> >>>      type: boolean
> >>>
> >>> +  xhci-no-soft-retry-quirk:
> >>> +    description: Set if the controller cannot perform xHCI Soft Retry correctly
> >>
> >> Why isn't this implied by compatible? Looks like controller's property.
> >
> > The xhci device is created by dwc3 core as a child device, and so
> > xhci_plat_probe() is used. I think a DT property is the right
> > approach, similar to quirk-broken-port-ped, but to set
> > XHCI_NO_SOFT_RETRY.
>
> Linux driver behavior should not matter here. DT property for telling
> Linux what to do is not the right approach. As I said, it's implied by
> compatible unless you bring hardware reasons why it is not. Driver
> reasons don't matter.

Will rework without DT property. Appreciate the feedback!

Best,
Matt