From: Conor Dooley <conor.dooley@microchip.com>
To: Vignesh Raghavendra <vigneshr@ti.com>
Cc: "Théo Lebrun" <theo.lebrun@bootlin.com>,
"Conor Dooley" <conor@kernel.org>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Rob Herring" <robh+dt@kernel.org>,
"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
"Conor Dooley" <conor+dt@kernel.org>,
"Roger Quadros" <rogerq@kernel.org>,
"Peter Chen" <peter.chen@kernel.org>,
"Pawel Laszczak" <pawell@cadence.com>,
"Nishanth Menon" <nm@ti.com>, "Tero Kristo" <kristo@kernel.org>,
"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
"Grégory Clement" <gregory.clement@bootlin.com>,
"Kevin Hilman" <khilman@kernel.org>,
"Alan Stern" <stern@rowland.harvard.edu>,
linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/8] dt-bindings: usb: ti,j721e-usb: drop useless compatible list
Date: Tue, 27 Feb 2024 08:07:02 +0000 [thread overview]
Message-ID: <20240227-radiated-fame-57a2e685f1b0@wendy> (raw)
In-Reply-To: <37ab0886-0cd1-4188-9177-8b7ef0ad9eca@ti.com>
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On Tue, Feb 27, 2024 at 09:54:30AM +0530, Vignesh Raghavendra wrote:
> On 26/02/24 20:05, Théo Lebrun wrote:
> > On Mon Feb 26, 2024 at 12:56 PM CET, Conor Dooley wrote:
> >> On Mon, Feb 26, 2024 at 11:33:06AM +0100, Théo Lebrun wrote:
> >>> Hello Conor,
> >>>
> >>> On Fri Feb 23, 2024 at 7:12 PM CET, Conor Dooley wrote:
> >>>> On Fri, Feb 23, 2024 at 05:05:25PM +0100, Théo Lebrun wrote:
> >>>>> Compatible can be A or B, not A or B or A+B. Remove last option.
> >>>>> A=ti,j721e-usb and B=ti,am64-usb.
> >>>>>
> >>>>> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> >>>>> ---
> >>>>> Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml | 9 +++------
> >>>>> 1 file changed, 3 insertions(+), 6 deletions(-)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml b/Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml
> >>>>> index 95ff9791baea..949f45eb45c2 100644
> >>>>> --- a/Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml
> >>>>> +++ b/Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml
> >>>>> @@ -11,12 +11,9 @@ maintainers:
> >>>>>
> >>>>> properties:
> >>>>> compatible:
> >>>>> - oneOf:
> >>>>> - - const: ti,j721e-usb
> >>>>> - - const: ti,am64-usb
> >>>>> - - items:
> >>>>> - - const: ti,j721e-usb
> >>>>> - - const: ti,am64-usb
> >>>>
> >>>> Correct, this makes no sense. The devices seem to be compatible though,
> >>>> so I would expect this to actually be:
> >>>> oneOf:
> >>>> - const: ti,j721e-usb
> >>>> - items:
> >>>> - const: ti,am64-usb
> >>>> - const: ti,j721e-usb
> >>>
> >>> I need your help to grasp what that change is supposed to express? Would
> >>> you mind turning it into english sentences?
> >>> A=ti,j721e-usb and B=ti,am64-usb. My understanding of your proposal is
> >>> that a device can either be compat with A or B. But B is compatible
> >>> with A so you express it as a list of items. If B is compat with A then
> >>> A is compat with B. Does the order of items matter?
> >>
> >> The two devices are compatible with each other, based on an inspection of
> >> the driver and the existing "A+B" setup. If this was a newly submitted
> >> binding, "B" would not get approved because "A+B" allows support without
> >> software changes and all that jazz.
> >>
> >> Your patch says that allowing "A", "B" and "A+B" makes no sense and you
> >> suggest removing "A+B". I am agreeing that it makes no sense to allow
> >> all 3 of these situations.
> >>
> >> What I also noticed is other problems with the binding. What should have
> >> been "A+B" is actually documented as "B+A", but that doesn't make sense
> >> when the originally supported device is "A".
This A and B stuff confused me, I should just have used the actual
compatibles. I meant
| What should have been "B+A" is actually documented as "A+B", but that
| doesn't make sense when the originally supported device is "A"
> >>
> >> Therefore my suggestion was to only allow "A" and "A+B", which is what
> >> we would (hopefully) tell you to do were you submitting the am64 support
> >> as a new patch today.
> >
> > Thank you for the in-depth explanation! It makes much more sense now,
> > especially the handling of historic stuff that ideally wouldn't have
> > been done this way but that won't be changed from now on.
> >
>
> IIRC, idea behind adding new compatible for AM64 even though register
> map is very much compatible is just being future proof as AM64 and J721e
> belong to different product groups and thus have differences wrt SoC
> level integration etc which may need SoC specific handling later on.
That is fine, I don't think anyone here is disputing a soc-specific
compatible existing for this device.
> Also, note that AM64 SoC support was added long after J721e. So ideally
> should be B+A if at all we need a fallback compatible.
Correct, I accidentally wrote "A+B", but you can see that that
conflicted with the actual example I had given above.
> I don't see any DT (now or in the past) using
>
> compatible = B,A or compatible = A,B
>
> So do we really need A+B to be supported by binding?
Given the mistake, I am going to take this as meaning should the
fallback be supported. My take is that if we are going to remove
something, it should be "ti,am64-usb" isolation that should go.
The devicetrees can be update without concerns about compatibility.
Cheers,
Conor.
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next prev parent reply other threads:[~2024-02-27 8:08 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-23 16:05 [PATCH v3 0/8] usb: cdns: fix suspend on J7200 by assuming reset-on-resume Théo Lebrun
2024-02-23 16:05 ` [PATCH v3 1/8] dt-bindings: usb: ti,j721e-usb: drop useless compatible list Théo Lebrun
2024-02-23 18:12 ` Conor Dooley
2024-02-26 10:33 ` Théo Lebrun
2024-02-26 11:56 ` Conor Dooley
2024-02-26 14:35 ` Théo Lebrun
2024-02-27 4:24 ` Vignesh Raghavendra
2024-02-27 8:07 ` Conor Dooley [this message]
2024-02-23 16:05 ` [PATCH v3 2/8] dt-bindings: usb: ti,j721e-usb: add ti,j7200-usb compatible Théo Lebrun
2024-02-23 18:13 ` Conor Dooley
2024-02-23 16:05 ` [PATCH v3 3/8] usb: cdns3-ti: move reg writes from probe into ->runtime_resume() Théo Lebrun
2024-02-23 16:05 ` [PATCH v3 4/8] usb: cdns3-ti: support reset-on-resume behavior Théo Lebrun
2024-02-24 9:08 ` Sergei Shtylyov
2024-02-26 10:13 ` Théo Lebrun
2024-02-27 16:27 ` Sergei Shtylyov
2024-02-23 16:05 ` [PATCH v3 5/8] usb: cdns3-ti: pass auxdata from match data to of_platform_populate() Théo Lebrun
2024-02-23 16:05 ` [PATCH v3 6/8] usb: cdns3: add quirk to platform data for reset-on-resume Théo Lebrun
2024-02-23 16:05 ` [PATCH v3 7/8] usb: cdns3-ti: add J7200 support with reset-on-resume behavior Théo Lebrun
2024-02-23 16:05 ` [PATCH v3 8/8] arm64: dts: ti: k3-j7200: use J7200-specific USB compatible Théo Lebrun
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