Re: [PATCH 20/20] arch: dts: Fix DWC USB3 DT nodes name

From: Maxime Ripard <maxime@cerno.tech>
To: Felipe Balbi <balbi@kernel.org>
Cc: "Andrew Lunn" <andrew@lunn.ch>,
	linux-usb@vger.kernel.org,
	"Neil Armstrong" <narmstrong@baylibre.com>,
	"Tony Lindgren" <tony@atomide.com>,
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	"Gregory Clement" <gregory.clement@bootlin.com>,
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	linux-snps-arc@lists.infradead.org,
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	"Alexey Malahov" <Alexey.Malahov@baikalelectronics.ru>,
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	linuxppc-dev@lists.ozlabs.org,
	"Patrice Chotard" <patrice.chotard@st.com>,
	"Serge Semin" <fancer.lancer@gmail.com>,
	"Li Yang" <leoyang.li@nxp.com>,
	"Serge Semin" <Sergey.Semin@baikalelectronics.ru>,
	"Manu Gautam" <mgautam@codeaurora.org>,
	"Benoît Cousson" <bcousson@baylibre.com>,
	"Shawn Guo" <shawnguo@kernel.org>,
	"Pavel Parkhomenko" <Pavel.Parkhomenko@baikalelectronics.ru>
Subject: Re: [PATCH 20/20] arch: dts: Fix DWC USB3 DT nodes name
Date: Thu, 15 Oct 2020 16:04:54 +0200	[thread overview]
Message-ID: <20201015140454.mctkhgkhegwdnfxk@gilmour.lan> (raw)
In-Reply-To: <875z7blrqu.fsf@kernel.org>

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On Thu, Oct 15, 2020 at 01:15:37PM +0300, Felipe Balbi wrote:
> Serge Semin <Sergey.Semin@baikalelectronics.ru> writes:
> 
> > On Wed, Oct 14, 2020 at 05:09:37PM +0300, Felipe Balbi wrote:
> >> 
> >> Hi Serge,
> >> 
> >> Serge Semin <Sergey.Semin@baikalelectronics.ru> writes:
> >> > In accordance with the DWC USB3 bindings the corresponding node name is
> >> > suppose to comply with Generic USB HCD DT schema, which requires the USB
> >> 
> >
> >> DWC3 is not a simple HDC, though.
> >
> > Yeah, strictly speaking it is equipped with a lot of vendor-specific stuff,
> > which are tuned by the DWC USB3 driver in the kernel. But after that the
> > controller is registered as xhci-hcd device so it's serviced by the xHCI driver,
> 
> in Dual-role or host-only builds, that's correct. We can also have
> peripheral-only builds (both SW or HW versions) which means xhci isn't
> even in the picture.

It doesn't really matter though, or at least it does for what the new
name might be, but the old one currently used is still pretty bad.

The DT spec says that the node name is the class of the device. "usb" as
the HCD binding mandates is one, but the current nodes currently have
completely different names from one DT to another - which is already an
issue - and most of them have dwc3 or some variant of it, which doesn't
really qualify for a class name.

Maxime

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