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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1FAEC433FE for ; Tue, 12 Oct 2021 12:52:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5D9260E05 for ; Tue, 12 Oct 2021 12:52:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236489AbhJLMyX (ORCPT ); Tue, 12 Oct 2021 08:54:23 -0400 Received: from mail-oi1-f178.google.com ([209.85.167.178]:43935 "EHLO mail-oi1-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236652AbhJLMyV (ORCPT ); Tue, 12 Oct 2021 08:54:21 -0400 Received: by mail-oi1-f178.google.com with SMTP id o4so28904852oia.10; Tue, 12 Oct 2021 05:52:20 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=GH/rUNldGDrQWZbHGHNnv3z7yGjMSKDvdbkj2ZpIpc4=; b=hWQcpbafOqEfhkzZUi+fyaX7CYCmIdeQdqEUayhs6BC7hdkzeTsR/hhzqkio0rpEoU tgdUQSjKI4hwtOMG77C6HoEU4sQBSgMoeKEHe4OrrQO6g5Ms/SDQMrZnPGd1cBKTU8vJ e4dglGMrolzLoTxC/enzyqJ0BS6QxwU86H+sKOaeQfmnng6t+nK3E1SMj7YQHi4Uhhck hj2yQHVHiPAKDkLHB3tSFqbdv1Wv/VgZgmHsYqJ2HCp/T6L3ESNQ2YxeT50j0G1DFduk VLoGXYc/9fkWYakp39Oa+VS7VTlZGH0yHWnvjgt7/1k8m948RPl66A/5Z6oAK82Q2i7h kV2w== X-Gm-Message-State: AOAM531ujTCIGfAbG/2K0TEj0CjdydsOcvr516pP5q+3Ud5swqHq7Y/M NPMOmJ8XKE54/8hwkXWaEQ== X-Google-Smtp-Source: ABdhPJz8As3l+5i35LUl/3j8/RYdO3uMxHOhk3l3WiuYe0C4KBDwdJpcQI1vNwr1VfPoZj4l4G6kSA== X-Received: by 2002:aca:6747:: with SMTP id b7mr3524949oiy.46.1634043139688; Tue, 12 Oct 2021 05:52:19 -0700 (PDT) Received: from robh.at.kernel.org (66-90-148-213.dyn.grandenetworks.net. [66.90.148.213]) by smtp.gmail.com with ESMTPSA id l45sm2090151ooi.30.2021.10.12.05.52.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Oct 2021 05:52:18 -0700 (PDT) Received: (nullmailer pid 2551195 invoked by uid 1000); Tue, 12 Oct 2021 12:52:17 -0000 Date: Tue, 12 Oct 2021 07:52:17 -0500 From: Rob Herring To: Alexander Stein Cc: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , Pratyush Yadav , Michael Walle , Tudor Ambarus , Alexander Stein , linux-mtd@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] dt-bindings: mtd: spi-nor: Add output-driver-strength property Message-ID: References: <20211004111529.211089-1-Alexander.Stein@tq-systems.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211004111529.211089-1-Alexander.Stein@tq-systems.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 04, 2021 at 01:15:28PM +0200, Alexander Stein wrote: > From: Alexander Stein > > This property is for optimizing output voltage impedance and is > specific to each board. > > Signed-off-by: Alexander Stein > --- > I checked Micron and Macronix datasheets. Both have similar but not > identical supported values. Also the register locations are different. > For those reasons I decided to specify the Ohms value directly and let > the device specfic driver figure out if it is supported where to write > it to. > BTW: Are the Ohm values and the corresponding register bits standardized > somewhere? > > Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml > index ed590d7c6e37..7d7f20a741b5 100644 > --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml > +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml > @@ -72,6 +72,12 @@ properties: > be used on such systems, to denote the absence of a reliable reset > mechanism. > > + output-driver-strength: > + $ref: /schemas/types.yaml#/definitions/uint32 > + description: > + Output driver strength in Ohms which optimizes the impedance at Vcc/2 > + output voltage. Use a standard unit suffix. Though, specifying 'drive strength' in ohms rather than amps is a bit strange.