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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4B09FC43441 for ; Wed, 10 Oct 2018 11:47:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F6D12086D for ; Wed, 10 Oct 2018 11:47:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sirena.org.uk header.i=@sirena.org.uk header.b="ai8e9Zyj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F6D12086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726893AbeJJTJA (ORCPT ); Wed, 10 Oct 2018 15:09:00 -0400 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:50696 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726562AbeJJTI6 (ORCPT ); Wed, 10 Oct 2018 15:08:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ROQ22YeAzEH+f9FA3bsiBp4avpbqC1fjIQ2vUuWWnf0=; b=ai8e9ZyjSGX50WZkNc9jIr39k +fA1jCZ2xWwvMswFptr+8n9v+ymWhs101AlhjxsnZzttg6DMzrCCJNn2qbqktlQRtWw694FvCgAbq zCnM/WBiyjybezGaxzv0d11VFDjCjTWpf6MBmLiLQkBTRvfGmYeoWfaxxRY7iVWGs/fR0=; Received: from cpc102320-sgyl38-2-0-cust46.18-2.cable.virginm.net ([82.37.168.47] helo=debutante.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpa (Exim 4.89) (envelope-from ) id 1gACxH-0007je-I6; Wed, 10 Oct 2018 11:47:07 +0000 Received: by debutante.sirena.org.uk (Postfix, from userid 1000) id 9CA4C1122392; Wed, 10 Oct 2018 12:27:53 +0100 (BST) Date: Wed, 10 Oct 2018 12:27:53 +0100 From: Mark Brown To: Talel Shenhar Cc: linux-spi@vger.kernel.org, robh+dt@kernel.org, mark.rutland@arm.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, ronenk@amazon.com, barakw@amazon.com, David Woodhouse Subject: Re: [PATCH 1/2] dt-bindings: spi: dw: add cs-override property Message-ID: <20181010112753.GC6294@sirena.org.uk> References: <1539155293-21750-1-git-send-email-talel@amazon.com> <20181010101825.GA6294@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="XWOWbaMNXpFDWE00" Content-Disposition: inline In-Reply-To: X-Cookie: Phasers locked on target, Captain. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --XWOWbaMNXpFDWE00 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Oct 10, 2018 at 02:23:40PM +0300, Talel Shenhar wrote: > On 10/10/2018 01:18 PM, Mark Brown wrote: > > On Wed, Oct 10, 2018 at 10:08:12AM +0300, Talel Shenhar wrote: > >> The dw spi controller has an auto-deselect of Chip-Select, in case there is > >> no data inside the Tx FIFO. While working on platforms with Alpine chips, > > Why would we ever want to use this behaviour? It will be broken for any > > non-trivial SPI message such as those made with multiple transfers > > anyway. Why not just unconditionally control it manually? > This behavior (auto-deselect of Chip-Select) is the default behavior of dw spi controller hw. > On Alpine chip there is additional behavior added to the dw spi controller hw that allows the sw to disable this behavior. > This patch allows the dw driver to enable this hw workaround and add the needed sw manual control for it. If this is a modified IP with additional features then it should be given a new compatible string rather than having a property - it's not just configuration of the existing IP, it's a new thing and we may find there are other quirks that have to be taken care of for it. --XWOWbaMNXpFDWE00 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlu94jgACgkQJNaLcl1U h9ApoQf/bZoqz6AzEschlNCke1wLPI98oWSDZLffCSfz9cw1bkrYYqkHInTWRcH6 kDWI4TUt7/y/Vfe2KZOB5B14B05XJh5y4NB21zLNc7BQCbmY1TPNHKb4Q/ums5qp cPnz+jyFf2wUrRBsu9MZ6G5LbwameBAjy0aw1YlIzvtMHovsT1TCoAcazwCWrZoD 5oe0ZTvJ5L8ht6ML7RQl2nRBVLlTlVmmxqlZwmomnhQ+meM9TkYORREI4AmfM5V1 CUMMwpg8BB7WA5SYhvgtdd4mZIw3uVrY66Xh1gIOq+zrIOxMDwzvva0pHoWYiuPn oiwyTZEzTYPdn4p3yum2O4EvASuj7g== =hB4N -----END PGP SIGNATURE----- --XWOWbaMNXpFDWE00--