Re: [PATCH v2 2/2] spi: npcm-pspi: Add NPCM845 peripheral SPI support

From: Tomer Maimon <tmaimon77@gmail.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Mark Brown <broonie@kernel.org>,
	Avi Fishman <avifishman70@gmail.com>,
	Tali Perry <tali.perry1@gmail.com>, Joel Stanley <joel@jms.id.au>,
	Patrick Venture <venture@google.com>,
	Nancy Yuen <yuenn@google.com>,
	Benjamin Fair <benjaminfair@google.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	OpenBMC Maillist <openbmc@lists.ozlabs.org>,
	linux-spi@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	devicetree <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] spi: npcm-pspi: Add NPCM845 peripheral SPI support
Date: Tue, 26 Jul 2022 22:32:56 +0300	[thread overview]
Message-ID: <CAP6Zq1iHCL9Krjw-wYKrG1K_yzwj-_qNROYxhogvkDjk+gCL-g@mail.gmail.com> (raw)
In-Reply-To: <20869b88-41f3-9e9c-347e-17c3d01baa5d@linaro.org>

Hi Krzysztof,

Thanks for your explanation.

On Tue, 26 Jul 2022 at 12:47, Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> On 24/07/2022 10:44, Tomer Maimon wrote:
> > Hi Mark and Krzysztof,
> >
> > Thanks for your reply,
> >
> > On Fri, 22 Jul 2022 at 21:57, Mark Brown <broonie@kernel.org> wrote:
> >>
> >> On Fri, Jul 22, 2022 at 08:47:24PM +0200, Krzysztof Kozlowski wrote:
> >>> On 22/07/2022 20:43, Mark Brown wrote:
> >>
> >>>> ...with a fallback list required by the bindings so the driver actually
> >>>> binds.  Note that bindings are currently not in YAML format so there'd
> >>>> be even less enforcement of that than normal, and as they're currently
> >>>> written the bindings don't require fallback.
> >>
> >>> Yes, the bindings document should be rephrased but we were living like
> >>> that for few years. :)
> >>
> >> The binding document as it stands only has one compatible, there's no
> >> existing problem with it other than the YAML conversion.  If we're
> >> adding something new that requires a fallback we should be explicit
> >> about that rather than have something that's actively misleading where
> >> previously things were clear.  I don't mind if we add the compatible to
> >> the driver or document the requirement for the fallback but we should do
> >> one of the two.
> >
> > is V2 good enough? adding the compatible to the driver and the document?
> > Or should we use fallback?
> > If fallback is choosen, can you explain how I should do it?
>
> I propose to use fallback. The preferred way is to convert it to DT
> schema and then add new device support (so two commits). Other
> acceptable way is to rephrase the TXT so it clearly states desired
> compatibles - one for old device, two for new devices. There are plenty
> of examples in current sources.
Appreciate if you could clarify.
in case we use DT-schema, we dont describe the fallback like we doing
in txt document?
I mean that in the yaml file we should describe the NPCM PSPI
compatible property as follow:
  compatible:
    enum:
      - nuvoton,npcm750-pspi
      - nuvoton,npcm845-pspi

If yes, how should the user know that he needs to use fallback incase
is using nuvoton,npcm845-pspi? only from the device tree?
>
>
> Best regards,
> Krzysztof

Best regards,

Tomer