Re: [PATCH 07/11] dt-bindings: spi: spi-nxp-fspi: add a new property nxp,fspi-dll-slvdly

From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
To: Han Xu <han.xu@nxp.com>, Bough Chen <haibo.chen@nxp.com>,
	"ashish.kumar@nxp.com" <ashish.kumar@nxp.com>,
	"yogeshgaur.83@gmail.com" <yogeshgaur.83@gmail.com>,
	"broonie@kernel.org" <broonie@kernel.org>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"krzysztof.kozlowski+dt@linaro.org"
	<krzysztof.kozlowski+dt@linaro.org>,
	"singh.kuldeep87k@gmail.com" <singh.kuldeep87k@gmail.com>,
	"tudor.ambarus@microchip.com" <tudor.ambarus@microchip.com>,
	"p.yadav@ti.com" <p.yadav@ti.com>,
	"michael@walle.cc" <michael@walle.cc>,
	"miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>,
	"richard@nod.at" <richard@nod.at>,
	"vigneshr@ti.com" <vigneshr@ti.com>,
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	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>
Cc: "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
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	"festevam@gmail.com" <festevam@gmail.com>,
	dl-linux-imx <linux-imx@nxp.com>,
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	<linux-arm-kernel@lists.infradead.org>,
	"zhengxunli@mxic.com.tw" <zhengxunli@mxic.com.tw>
Subject: Re: [PATCH 07/11] dt-bindings: spi: spi-nxp-fspi: add a new property nxp,fspi-dll-slvdly
Date: Tue, 5 Jul 2022 16:03:35 +0200	[thread overview]
Message-ID: <777026d0-578c-500f-7da4-0e81fc211df2@linaro.org> (raw)
In-Reply-To: <DU2PR04MB877492F346BAA10B2AA7428497819@DU2PR04MB8774.eurprd04.prod.outlook.com>

On 05/07/2022 16:00, Han Xu wrote:
>> So we probably misunderstood each other... looking at the driver it also explains
>> the confusing. You encoded here register value which is pretty often wrong
>> approach.
>>
>> This should be instead meaningful value for the user of the bindings, so usually
>> using one of property units:
>> https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com
>> %2Fdevicetree-org%2Fdt-
>> schema%2Fblob%2Fmain%2Fdtschema%2Fschemas%2Fproperty-
>> units.yaml&amp;data=05%7C01%7Chan.xu%40nxp.com%7C0ffe3d706e064f14382
>> 108da5e8a5add%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6379262
>> 45564450475%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV
>> 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=Q4
>> SfVnBN%2BQ0vYKJzRf%2FXZkCA1WGyPV9doFcb%2BLSKx4w%3D&amp;reserved=0
>>
>> I think you could use here clock cycles or clock phase, but then it has to be obvious
>> it is that unit.
> 
> Hi Krzysztof, 
> 
> Let me clarify it, in the document a term "delay cell" was used to descript this register bit. 

Which document? The bindings (I cannot find it there)? Commit msg?

> Each delay cell equals "1/32 clock phase", so the unit of delay cell is clock phase. The value user need set in DT just number to define how many delay cells needed.

Your bindings did not say this at all.

Best regards,
Krzysztof

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