From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: Neil Armstrong <neil.armstrong@linaro.org>,
Chen-Yu Tsai <wenst@chromium.org>
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Felipe Balbi" <balbi@kernel.org>,
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"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
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Subject: Re: [PATCH 2/2] dt-bindings: usb: snps,dwc3: Fix downstream port numbering
Date: Wed, 14 Oct 2026 18:36:06 +0200 [thread overview]
Message-ID: <b4c0761b-34f2-42ad-97e7-ab34ae776281@oss.qualcomm.com> (raw)
In-Reply-To: <03375a31-0ac6-47a4-b0dc-6327080e1622@linaro.org>
On 10/14/26 11:44 AM, Neil Armstrong wrote:
> On 10/14/26 11:29, Chen-Yu Tsai wrote:
>> On Wed, Oct 14, 2026 at 5:28 PM Neil Armstrong
>> <neil.armstrong@linaro.org> wrote:
>>>
>>> On 10/14/26 10:20, Chen-Yu Tsai wrote:
>>>> The DWC3 controller can operate in host mode. It does so with a XHCI
>>>> compliant host controller. The XHCI has two downstream ports, one for
>>>> HS and one for SS. USB downstream ports start from 1, not 0.
[...]
>> IMHO having consistent numbering across controller types would be
>> better. This avoids making the USB core and hub code deal with more
>> exceptions, and also easier to understand and write device trees.
>
> I was in the impression the port number not necessarily reflects
> an actual physical numbering, and can be a logical number we would
> then map in the kernel.
>
> I don't see any issue here having base 0 for the bindings and then
> converting it to base 1 for the XHCI port numbering.
I thought base1 comes from the USB spec and not just XHCI?
Konrad
prev parent reply other threads:[~2026-10-14 16:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 8:20 [PATCH 0/2] dt-bindings: usb: downstream host ports for hcd and dwc3 Chen-Yu Tsai
2026-10-14 8:20 ` [PATCH 1/2] dt-bindings: usb: hcd: Add downstream USB ports Chen-Yu Tsai
2026-10-14 8:20 ` [PATCH 2/2] dt-bindings: usb: snps,dwc3: Fix downstream port numbering Chen-Yu Tsai
2026-10-14 8:28 ` Neil Armstrong
2026-10-14 9:29 ` Chen-Yu Tsai
2026-10-14 9:44 ` Neil Armstrong
2026-10-14 10:14 ` Chen-Yu Tsai
2026-10-14 12:15 ` Neil Armstrong
2026-10-14 16:36 ` Konrad Dybcio [this message]
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