From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 053D128B7F0; Wed, 9 Jul 2025 10:16:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752056187; cv=none; b=Pxe+sj1t562CFYYtLK5CszYVgpd5ILRIG7AwOPEBVPRlvF8xbV4CtYLHkdvteNmetpaxxBLY+OFPLLILhTViQIO+HohnCnXGFJhNIOk4Ru79JKlXYz1ISaEBj8fktOSXb4/NnF7DoETXGfnbZzvhqyQRuC9zLA28F+l1Ja7HlzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752056187; c=relaxed/simple; bh=WU1rxoEN5qTryIgIVLvNxwFkuceff06Lwe4kPoXlgC4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YPasveM9+c2ToHg8Lc/m2l5ki4Pu5Aru/UDORSKXPLXaEJfJj963AFoD1weEwvi1DKYSbek9ozDbT/XVd5T9Fyr1Y3Ad1Xl5jNld3xwLSigDpufPzXmC7TNLrIpjLQhHuBTLfjAzICCiNZIjXWk50ePI51UzmUGp2u7IrEkCP3g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lyFDM1De; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lyFDM1De" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60D75C4CEEF; Wed, 9 Jul 2025 10:16:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752056186; bh=WU1rxoEN5qTryIgIVLvNxwFkuceff06Lwe4kPoXlgC4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lyFDM1DeGTIjOy6NpG5MKSX/cYOs/Xta57Tb8MAbFiOLsGgokVrlsI9crvwa3xBqT 1MvGcz5Qm+jRZBKbaCvrgT41ifM3rTCmOriWm+DR7RF1Wvtu9pKOBG1K8yRTdME69X 1c56b7DmtTiBkO5V7QYo33rwxxI6PPMF1EXV0JUCBJBUDCzDBRn0dFGXqN0Rh+6262 C/RGmn7TrUiSH1cClo8uhJ1kMO5XyeVhrRppwLI0EqUcT92EwB5hpfHs0cgEe5cAZ6 arQQohbHvRPr5DhP8gt1+usi0wS3TKVm3WiL2clx/WIYS4gQq0L1wtHsqvxiQLcKyj Rq3ADv0iEO7vQ== Message-ID: <1c7fdeca-d531-4f90-9e4c-4d8bfac67fae@kernel.org> Date: Wed, 9 Jul 2025 12:16:21 +0200 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] dt-bindings: phy: qcom,snps-eusb2-repeater: Document qcom,tune-res-fsdif To: Luca Weiss Cc: Vinod Koul , Kishon Vijay Abraham I , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Abel Vesa , ~postmarketos/upstreaming@lists.sr.ht, phone-devel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250625-sm7635-eusb-repeater-v1-0-19d85541eb4c@fairphone.com> <20250625-sm7635-eusb-repeater-v1-1-19d85541eb4c@fairphone.com> <20250708-unicorn-of-ancient-excellence-e8945c@krzk-bin> <20250708-stoic-slim-bison-ac55ee@krzk-bin> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 09/07/2025 11:40, Luca Weiss wrote: > Hi Krzysztof, > > On Tue Jul 8, 2025 at 10:31 AM CEST, Luca Weiss wrote: >> On Tue Jul 8, 2025 at 10:21 AM CEST, Krzysztof Kozlowski wrote: >>> On Tue, Jul 08, 2025 at 10:13:24AM +0200, Krzysztof Kozlowski wrote: >>>> On Wed, Jun 25, 2025 at 11:14:56AM +0200, Luca Weiss wrote: >>>>> Document the FS Differential TX Output Resistance Tuning value found on >>>>> the eUSB2 repeater on Qualcomm PMICs. >>>>> >>>>> Signed-off-by: Luca Weiss >>>>> --- >>>>> Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml | 6 ++++++ >>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml b/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> index 27f064a71c9fb8cb60e8333fb285f0510a4af94f..6bfd11657e2992735998063b3ca390e04a03930d 100644 >>>>> --- a/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> +++ b/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> @@ -52,6 +52,12 @@ properties: >>>>> minimum: 0 >>>>> maximum: 7 >>>>> >>>>> + qcom,tune-res-fsdif: >>>>> + $ref: /schemas/types.yaml#/definitions/uint8 >>>>> + description: FS Differential TX Output Resistance Tuning >>>> >>>> Resistance is in Ohms, tuning could be in dB, so I wonder what are the >>>> actual units here. Neither commit msg nor this description helps me to >>>> understand that. >>> >>> I checked and the values are in Ohms. >> >> Yes it's Ohms but not 0x00 = 0 ohms, and it's also an offset in ohms >> from the nominal value according to the Hardware Register Description I >> have, e.g. 0x7 = -12.1ohm from the default >> >> I can try and create bindings using these Ohm offset values, I didn't >> worry about it too much since the other tuning values in these bindings >> are also just register values, presumably from before Konrad had access >> to the docs. > > I've taken some more looks, and checked how similar tuning is handled in > qcom,usb-snps-femto-v2.yaml and phy-qcom-snps-femto-v2.c, and changing up > the concept of tuning in the eUSB2-repeater bindings+driver is not a > trivial task. > > Since this is adding just one more property in-line with the already > supported properties in the bindings+driver, can we get this in as-is, > and deprecate all 4 qcom,tune-* properties later with a replacement that > describes the values better? This is a new property, so other existing properties do not matter here. We cannot take new code which you already think should be deprecated. register-like values are acceptable for vendor properties, but that does not make them usually more readable. The question is whether this should be more readable for hardware engineers or anyone writing/validating DTS. Is the actual resistance important or no one ever cares because you paste whatever qcom told you and you do not know what should be actually there? I can imagine the first - that some document explains you should have resistance of foo because of bar, which would mean the property should be more readable. But I can also imagine the second. Make your claim in commit msg. > We have enough people at Qualcomm by now that should be able to do that, > and have the required resources to answer any potential questions. They are busy sending vendor/downstream tree patches... Best regards, Krzysztof 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D2209C83F03 for ; Wed, 9 Jul 2025 12:05:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=HpPPqgLNsroSd2vWPSFRndVf2gtSvUG+bP29IWAMfBo=; b=VMlqM5NkrjSV1a /GEN4jAMo3hFrJtRYZrX8WbbGPIQ3Mur/SPhlyihKo3N9+VowVomb4jOpDTuxPuZJCpK9Law3PN1S LRIGVQGTI+ONNPlHTqtDuozSdpVWBGKacgrattNFToPqJ33ZpO81ypoamUzLv0dIdTfKrG8P4ZHiG 7Uvve7nCXyuOus2inPwpfqRvjmK7/J3r5kB250x6d6FIS7QA8yf+WCd9L4xnt1UWOwFqKeWxsbRds V1IuL1lFG+d2GhbnBZJtDDP4VJ477THqU1xQFABFRu7dM2l91dJHum4Bx0gLUki3jl8XxSbNLVERj 9ZCm/TvVKE3+ZJQmn5nA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uZTYK-00000008a7C-21V0; Wed, 09 Jul 2025 12:05:32 +0000 Received: from nyc.source.kernel.org ([2604:1380:45d1:ec00::3]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uZRqm-00000008HR0-27eD for linux-phy@lists.infradead.org; Wed, 09 Jul 2025 10:16:29 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id CD34BA5400D; Wed, 9 Jul 2025 10:16:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60D75C4CEEF; Wed, 9 Jul 2025 10:16:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752056186; bh=WU1rxoEN5qTryIgIVLvNxwFkuceff06Lwe4kPoXlgC4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lyFDM1DeGTIjOy6NpG5MKSX/cYOs/Xta57Tb8MAbFiOLsGgokVrlsI9crvwa3xBqT 1MvGcz5Qm+jRZBKbaCvrgT41ifM3rTCmOriWm+DR7RF1Wvtu9pKOBG1K8yRTdME69X 1c56b7DmtTiBkO5V7QYo33rwxxI6PPMF1EXV0JUCBJBUDCzDBRn0dFGXqN0Rh+6262 C/RGmn7TrUiSH1cClo8uhJ1kMO5XyeVhrRppwLI0EqUcT92EwB5hpfHs0cgEe5cAZ6 arQQohbHvRPr5DhP8gt1+usi0wS3TKVm3WiL2clx/WIYS4gQq0L1wtHsqvxiQLcKyj Rq3ADv0iEO7vQ== Message-ID: <1c7fdeca-d531-4f90-9e4c-4d8bfac67fae@kernel.org> Date: Wed, 9 Jul 2025 12:16:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] dt-bindings: phy: qcom,snps-eusb2-repeater: Document qcom,tune-res-fsdif To: Luca Weiss Cc: Vinod Koul , Kishon Vijay Abraham I , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Abel Vesa , ~postmarketos/upstreaming@lists.sr.ht, phone-devel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250625-sm7635-eusb-repeater-v1-0-19d85541eb4c@fairphone.com> <20250625-sm7635-eusb-repeater-v1-1-19d85541eb4c@fairphone.com> <20250708-unicorn-of-ancient-excellence-e8945c@krzk-bin> <20250708-stoic-slim-bison-ac55ee@krzk-bin> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org On 09/07/2025 11:40, Luca Weiss wrote: > Hi Krzysztof, > > On Tue Jul 8, 2025 at 10:31 AM CEST, Luca Weiss wrote: >> On Tue Jul 8, 2025 at 10:21 AM CEST, Krzysztof Kozlowski wrote: >>> On Tue, Jul 08, 2025 at 10:13:24AM +0200, Krzysztof Kozlowski wrote: >>>> On Wed, Jun 25, 2025 at 11:14:56AM +0200, Luca Weiss wrote: >>>>> Document the FS Differential TX Output Resistance Tuning value found on >>>>> the eUSB2 repeater on Qualcomm PMICs. >>>>> >>>>> Signed-off-by: Luca Weiss >>>>> --- >>>>> Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml | 6 ++++++ >>>>> 1 file changed, 6 insertions(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml b/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> index 27f064a71c9fb8cb60e8333fb285f0510a4af94f..6bfd11657e2992735998063b3ca390e04a03930d 100644 >>>>> --- a/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> +++ b/Documentation/devicetree/bindings/phy/qcom,snps-eusb2-repeater.yaml >>>>> @@ -52,6 +52,12 @@ properties: >>>>> minimum: 0 >>>>> maximum: 7 >>>>> >>>>> + qcom,tune-res-fsdif: >>>>> + $ref: /schemas/types.yaml#/definitions/uint8 >>>>> + description: FS Differential TX Output Resistance Tuning >>>> >>>> Resistance is in Ohms, tuning could be in dB, so I wonder what are the >>>> actual units here. Neither commit msg nor this description helps me to >>>> understand that. >>> >>> I checked and the values are in Ohms. >> >> Yes it's Ohms but not 0x00 = 0 ohms, and it's also an offset in ohms >> from the nominal value according to the Hardware Register Description I >> have, e.g. 0x7 = -12.1ohm from the default >> >> I can try and create bindings using these Ohm offset values, I didn't >> worry about it too much since the other tuning values in these bindings >> are also just register values, presumably from before Konrad had access >> to the docs. > > I've taken some more looks, and checked how similar tuning is handled in > qcom,usb-snps-femto-v2.yaml and phy-qcom-snps-femto-v2.c, and changing up > the concept of tuning in the eUSB2-repeater bindings+driver is not a > trivial task. > > Since this is adding just one more property in-line with the already > supported properties in the bindings+driver, can we get this in as-is, > and deprecate all 4 qcom,tune-* properties later with a replacement that > describes the values better? This is a new property, so other existing properties do not matter here. We cannot take new code which you already think should be deprecated. register-like values are acceptable for vendor properties, but that does not make them usually more readable. The question is whether this should be more readable for hardware engineers or anyone writing/validating DTS. Is the actual resistance important or no one ever cares because you paste whatever qcom told you and you do not know what should be actually there? I can imagine the first - that some document explains you should have resistance of foo because of bar, which would mean the property should be more readable. But I can also imagine the second. Make your claim in commit msg. > We have enough people at Qualcomm by now that should be able to do that, > and have the required resources to answer any potential questions. They are busy sending vendor/downstream tree patches... Best regards, Krzysztof -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy