[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID:
<SEYPR01MB4221C23C14DB53299E2E2F12D7DE2@SEYPR01MB4221.apcprd01.prod.exchangelabs.com>
Date: Thu, 4 Jul 2024 08:25:10 +0000
From: Haylen Chu <heylenay@...look.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Conor Dooley <conor@...nel.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Zhang Rui <rui.zhang@...el.com>, Lukasz Luba <lukasz.luba@....com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Chen Wang <unicorn_wang@...look.com>,
Inochi Amaoto <inochiama@...look.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Jisheng Zhang <jszhang@...nel.org>, linux-pm@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v3 1/3] dt-bindings: thermal: sophgo,cv1800-thermal: Add
Sophgo CV1800 thermal
On Tue, Jul 02, 2024 at 05:09:35PM +0200, Krzysztof Kozlowski wrote:
> >> +
> >> +properties:
> >> + compatible:
> >> + enum:
> >> + - sophgo,cv1800-thermal
> >> +
> >> + reg:
> >> + maxItems: 1
> >> +
> >> + clocks:
> >> + description: The thermal sensor clock
> >> +
> >> + interrupts:
> >> + maxItems: 1
> >> +
> >> + accumulation-period:
> >> + $ref: /schemas/types.yaml#/definitions/uint32
> >> + description: Accumulation period for a sample
> >> + enum:
> >> + - 512
> >> + - 1024
> >> + - 2048
> >> + - 4096
> >> + default: 2048
> >> +
> >> + chop-period:
>
> period in what sort of units? Sounds like time to me, so this would
> require proper unit suffix.
In clock ticks.
When setting to 1024, a time of sample takes (1024 + 2 + 64) clock
ticks. The clock runs at (25MHz / divider) and the divider is
configurable.
> >
> >> + description: Period between samples. Should be greater than 524us.
> >
> > The constraint here should be "minimum: 524". What's the upper limit?
> >
> >> + default: 1000000
> >
> > Rob/Krzysztof, could you comment on the suitability of the three custom
> > properties here? I know if this was an IIO device, these kinds of things
> > would be controllable from userspace, and not in the binding. I
> > mentioned this on the previous version, but I'm not really sure if
> > thermal devices are somehow different:
> > https://lore.kernel.org/all/SEYPR01MB4221A739D0645EF0255336EBD7CE2@SEYPR01MB4221.apcprd01.prod.exchangelabs.com/
> >
>
> Why would different boards have different values here? Does it affect
> accuracy? If so, how much?
>
> I doubt there are any boards with different values, thus it sounds like
> unnecessary tuning parameter.
Theses values affect accuracy in a minor way (about 1 Celsius degree in
my test) and could be shared between CV18xx/SG20xx SoCs as they have the
same design.
In the first revision, fixed values are used, and I was asked to add
support for all possible configuration[1]. Now I think this introduces
extra unnecessary complexity and should be avoided, since this is a
simple thermal sensor, tuning seems to be useless.
I suggest renaming "sample-cycle-us" to "sample-rate-hz" and dropping
other parameters for simplicity.
Best regards,
Haylen Chu
[1]: https://lore.kernel.org/all/IA1PR20MB49533177BEFC431FC16D1AB8BBF32@IA1PR20MB4953.namprd20.prod.outlook.com/
Powered by blists - more mailing lists