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 1C65EC001DE for ; Tue, 8 Aug 2023 16:06:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231759AbjHHQGp (ORCPT ); Tue, 8 Aug 2023 12:06:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231426AbjHHQFe (ORCPT ); Tue, 8 Aug 2023 12:05:34 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C49FE30C7; Tue, 8 Aug 2023 08:45:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5E0F86259F; Tue, 8 Aug 2023 14:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D866C433C7; Tue, 8 Aug 2023 14:28:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691504894; bh=qMriDtXrpLpfOWzb5+F5aOCYEZhH3+5fP0nhoxADdxA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tV/68gEXuyvM/3aR/Qp/99bWWBgEJWNV2ioFTuNK7maHxoA1B+jr4legADPGIpFmC TdlpfRfEciPYC863Fr1g9haSn9B6FuQ3YFQQcWcYtAr3XM1PDaDLeJYHG3t47A4Chw UePvtRvh7fol4x07yLv8vsqeQn8LoyKEuJWEzMceYnNDdk/UBRmeCnS3r3upT33N7F wef4uKoHfk0fO2u7TR874aKZ8TochZneW8BekRHnLwTLS+D9DmohjHcNFHmugnARaT Cmqda5nh8N4n+7M0qOsDiPlx8rWolfpIt/xBVePqjkzPi25YffJO9H1VE4N+DFwxnH oZQs+tSbh3JXA== Date: Tue, 8 Aug 2023 15:28:10 +0100 From: Conor Dooley To: Guenter Roeck Cc: Naresh Solanki , Jean Delvare , krzysztof.kozlowski+dt@linaro.org, Rob Herring , Conor Dooley , linux-hwmon@vger.kernel.org, Patrick Rudolph , Rob Herring , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/3] dt-bindings: hwmon: Add Infineon TDA38640 Message-ID: <20230808-esquire-epidemic-f9bd74ffde25@spud> References: <20230802193155.2170935-1-Naresh.Solanki@9elements.com> <20230808-stand-cheddar-b76b0b7509a0@spud> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="XfJu5TZS5xk5xqji" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --XfJu5TZS5xk5xqji Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 08, 2023 at 07:10:08AM -0700, Guenter Roeck wrote: > On 8/8/23 04:46, Conor Dooley wrote: > > On Wed, Aug 02, 2023 at 09:31:51PM +0200, Naresh Solanki wrote: > > > From: Patrick Rudolph > > >=20 > > > The TDA38640 chip has different output control mechanisms depending on > > > its mode of operation. When the chip is in SVID mode, only > > > hardware-based output control is supported via ENABLE pin. However, w= hen > > > it operates in PMBus mode, software control works perfectly. > > >=20 > > > To enable software control as a workaround in SVID mode, add the DT > > > property 'infineon,en-svid-control'. This property will enable the > > > workaround, which utilizes ENABLE pin polarity flipping for output wh= en > > > the chip is in SVID mode. > >=20 > > Why do you need a custom property for this? How come it is not possible > > to determine what bus you are on? > >=20 >=20 > That is not the point. Yes, it can be detected if the control method is > PMBus or SVID. However, in SVID mode, SVID is supposed to control the > output, not PMBUs. This is bypassed by controlling the polarity of the > (physical) output enable signal. We do _not_ want this enabled automatica= lly > in SVID mode. Its side effects on random boards using this chip are unkno= wn. > Thus, this needs a property which specifically enables this functionality > for users who _really_ need to use it and (hopefully) know what they are > doing. Hmm, reading this it makes a lot more sense why this is a property - I guess I just struggled to understand the commit message here, particularly what the benefit of using the workaround is. I'm still having difficulty parsing the commit & property text though - its unclear to me when you would need to use it - so I will stay out of the way & let Rob or Krzysztof handle things. --XfJu5TZS5xk5xqji Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZNJQ+gAKCRB4tDGHoIJi 0rsaAP4p4HX4bMrdis5l4TikUX588o40cMUso+iMzqcRc+4sBQEAiZOIdiIzqofV HE+wZrIM/ImGNTwKIwWUHO0dKzccKg8= =+V64 -----END PGP SIGNATURE----- --XfJu5TZS5xk5xqji--