From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2EAEC77B75 for ; Tue, 18 Apr 2023 09:44:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230002AbjDRJoE (ORCPT ); Tue, 18 Apr 2023 05:44:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229597AbjDRJnl (ORCPT ); Tue, 18 Apr 2023 05:43:41 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 938D159E8 for ; Tue, 18 Apr 2023 02:43:32 -0700 (PDT) Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1pohry-0000pw-4o; Tue, 18 Apr 2023 11:43:26 +0200 Message-ID: <67d283f3-d0db-5fc0-79e9-e7531d591aab@pengutronix.de> Date: Tue, 18 Apr 2023 11:42:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 1/2] dt-bindings: phy: imx8mq-usb: add phy tuning properties Content-Language: en-US, de-DE From: Johannes Zink To: Rob Herring Cc: kishon@kernel.org, devicetree@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org, festevam@gmail.com, s.hauer@pengutronix.de, vkoul@kernel.org, haibo.chen@nxp.com, linux-kernel@vger.kernel.org, Krzysztof Kozlowski , linux-imx@nxp.com, kernel@pengutronix.de, linux-phy@lists.infradead.org, shawnguo@kernel.org, linux-arm-kernel@lists.infradead.org, jun.li@nxp.com References: <20230405112118.1256151-1-j.zink@pengutronix.de> <20230405112118.1256151-2-j.zink@pengutronix.de> <5398cbe0-c681-5dd7-0b3e-3a586cc4915f@linaro.org> <3f7257ee36dc44f162a87281c8279fd5bad91dea.camel@pengutronix.de> <95b4afd4-c93e-628b-fd22-6fcbc1d1234e@linaro.org> <20230412133921.GA2017891-robh@kernel.org> <6953b608-973f-c603-f852-edf7ba183e64@pengutronix.de> In-Reply-To: <6953b608-973f-c603-f852-edf7ba183e64@pengutronix.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2a0a:edc0:0:900:1d::77 X-SA-Exim-Mail-From: j.zink@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: devicetree@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi Rob, hi Krzysztof, On 4/12/23 16:32, Johannes Zink wrote: > Hi Rob, > > On 4/12/23 15:39, Rob Herring wrote: >> On Tue, Apr 11, 2023 at 04:22:37PM +0200, Johannes Zink wrote: >>> Hi Krzystof, >>> >>> thank you for your explanations. As I'm still quite new to writing >>> bindings, I still have some questions: >>> >>> On Fri, 2023-04-07 at 11:03 +0200, Krzysztof Kozlowski wrote: >>>> On 05/04/2023 14:14, Johannes Zink wrote: >>>>> Hi Krysztof, >>>>> >>>>> thanks for your review, please find my questions below. >>>>> >>>>> On Wed, 2023-04-05 at 13:51 +0200, Krzysztof Kozlowski wrote: >>>>>> [snip] >>>>>>>         A phandle to the regulator for USB VBUS. >>>>>>> +  fsl,phy-tx-vref-tune: >>>>>>> +    description: >>>>>>> +      HS DC Voltage level adjustment >>>>>> >>>>>> "Level" in what units? >>>>>> >>>>> >>>>> The datasheet just shows percent, ranging from -6 to +24%, in 2% >>>>> increments. What unit would you suggest? >>>> >>>> percent >>>> https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml >>> >>> I am still a bit confused how to use this properly. How can I restrict >>> the values to multiples of 2 in order to avoid illegal values? >>> >>> At the moment the only thing I could come up with is something like >>> >>> fsl,phy-tx-vref-tune-percent: >>>    description: | >>>      Adjusts the high-speed DC level voltage >>>    $ref: /schemas/types.yaml#/definitions/int32 >> >> Note that with standard unit suffixes, you don't need a type. >> >>>    minimum: -6 >>>    maximum: 24 >>>    default: 0 >>> >>> Does something like this work? I am not quite sure if I am on the right >>> track here, especially as this requires a signed int, of which I have >>> not seen many examples so far. >> >> We'd have to change the type for -percent to signed. That's possible, >> but for vendor specific properties there's not much advantage to use >> standard units instead of just using the register values directly. >> > > I don't have any objections to that, this is pretty much what I sent in > my v1 patch <20230405112118.1256151-2-j.zink@pengutronix.de>, but > Krzysztof requested to change the vendor specific properties to use > property-units. > > Would something along the lines of the st,trim-hs-current on > Documentation/devicetree/bindings/phy/phy-stm32-usbphyc.yaml be > acceptable (i.e. use an enum and annotate the meaning of the values in > the description)? > > I will, nevertheless, try to make the descriptions a bit more verbose in > my v2 (wherever the datasheet gives me proper informations), as > Krzysztof requested. gentle ping - any opinions on this? Shall I just send a V2 along the lines of the phy-stm32-usbphy.c? Best regards Johannes > > Best regards > Johannes > >> Rob >> > -- Pengutronix e.K. | Johannes Zink | Steuerwalder Str. 21 | https://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686| Fax: +49-5121-206917-5555 |