From patchwork Fri Oct 18 14:12:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matt Porter X-Patchwork-Id: 3067751 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 057DCBF924 for ; Fri, 18 Oct 2013 14:13:00 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E551020397 for ; Fri, 18 Oct 2013 14:12:58 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A79922039A for ; Fri, 18 Oct 2013 14:12:57 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VXAnM-00038h-Mq; Fri, 18 Oct 2013 14:12:52 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VXAnK-0004wo-9L; Fri, 18 Oct 2013 14:12:50 +0000 Received: from mail-ie0-x22c.google.com ([2607:f8b0:4001:c03::22c]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VXAnI-0004vq-6W for linux-arm-kernel@lists.infradead.org; Fri, 18 Oct 2013 14:12:48 +0000 Received: by mail-ie0-f172.google.com with SMTP id tp5so6634500ieb.31 for ; Fri, 18 Oct 2013 07:12:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:subject:message-id:mime-version:content-type :content-disposition:user-agent; bh=rfmsqNA/0kF7UtmsbVPVmDoehNPDzCAjWEgXICw2eFg=; b=r0cpXokHVzkos7SxJcbBFUsQ6k4rJ9CYTdGJZwHWnS8FZFhiF7Nx/yp8F4dBh5netU 4eKU86CCSeuTzE+gGoBnkPb6k/KXmfINJvQljKls93GisPP993sq5XELueAo4moKkpx/ sKqr2ROBw9j/EVK1TlrSz6mUbZUfo4FHW+NdNG27GzKF780y3PF8Ln61oXOaNEroj4Gf ByM/VXn3RK8kcs1Zi1o+b2RLSY+zZcv6CuuspyNMHWl/m7GwTln55P6mbvruPdSnDn0i wMdjw1JX7g9RibVHLvDVKvcuT0UueQAygXVyp8oKO2zmus0l/fdoPvNEywGOm+1BzzfQ RU3A== X-Received: by 10.43.151.12 with SMTP id kq12mr1123048icc.55.1382105544786; Fri, 18 Oct 2013 07:12:24 -0700 (PDT) Received: from beef (cpe-98-27-254-98.neo.res.rr.com. [98.27.254.98]) by mx.google.com with ESMTPSA id p7sm1700663iga.3.2013.10.18.07.12.23 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Fri, 18 Oct 2013 07:12:24 -0700 (PDT) Date: Fri, 18 Oct 2013 10:12:21 -0400 From: Matt Porter To: Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Felipe Balbi , Kishon Vijay Abraham I , Greg Kroah-Hartman , Paul Zimmerman , Devicetree List , Linux USB List , Linux ARM Kernel List , Linux Kernel Mailing List Subject: [RFC] Does PHY UTMI data width belong to DWC2 or PHY binding? Message-ID: <20131018141221.GH2721@beef> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131018_101248_286887_7EF60C55 X-CRM114-Status: GOOD ( 12.73 ) X-Spam-Score: -1.9 (-) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This is a summary of an unresolved issue resulting from this thread: http://www.spinics.net/lists/arm-kernel/msg277700.html The BCM281xx family of SoCs contain an OTG subsystem consisting of a DWC2 HSOTG controller and an internal UTMI PHY. This is appears as follows (monospace font requirement ahead): +----------------+ +-----------------+ | | | | | | 8 | | | DWC2 |<------/----->| BCM Kona | | | UTMI | UTMI PHY | | | | | +----------------+ +-----------------+ The internal UTMI phy is connected via an 8-bit data path. There is no way to autodetect whether the data path is 8-bit or 16-bit. As such, it was determined that a DT property is necessary to reflect this. In the original patch submitted this property was offered as an additional optional dwc2 property: The open question is whether this required hardware property belongs to the DWC2 controller or the PHY itself. If the UTMI data path width is considered to be a property of the PHY then this will impact both the generic PHY framework and the PHY device node (producer) binding. The binding would need to be extended to carry the data path width property. In addition, the generic PHY framework would need to allow for this information to be gathered in some manner for use by the controller driver (PHY consumer). In the case of DWC2, the driver needs to know whether to program the phy interface for 8 or 16 bit UTMI communication. Thanks, Matt --- a/Documentation/devicetree/bindings/staging/dwc2.txt +++ b/Documentation/devicetree/bindings/staging/dwc2.txt @@ -6,10 +6,14 @@ Required properties: - reg : Should contain 1 register range (address and length) - interrupts : Should contain 1 interrupt +Optional properties: +- snps,phy-utmi-width: Must contain the UTMI data width (either 8 or 16) + Example: usb@101c0000 { compatible = "ralink,rt3050-usb, snps,dwc2"; reg = <0x101c0000 40000>; interrupts = <18>; + snps,phy-utmi-width = <8>; };