Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760734AbbKTQD7 (ORCPT ); Fri, 20 Nov 2015 11:03:59 -0500 Received: from mail.kernel.org ([198.145.29.136]:58857 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759721AbbKTQD4 (ORCPT ); Fri, 20 Nov 2015 11:03:56 -0500 Date: Fri, 20 Nov 2015 10:03:46 -0600 From: Rob Herring To: Marcus Weseloh Cc: linux-sunxi@googlegroups.com, Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Maxime Ripard , Mark Brown , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH] spi: dts: sun4i: Add support for inter-word wait cycles using the SPI Wait Clock Register Message-ID: <20151120160346.GA21921@rob-hp-laptop> References: <1447948422-4915-1-git-send-email-mweseloh42@gmail.com> <1447948422-4915-2-git-send-email-mweseloh42@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1447948422-4915-2-git-send-email-mweseloh42@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1807 Lines: 38 On Thu, Nov 19, 2015 at 04:53:42PM +0100, Marcus Weseloh wrote: > Adds support and documentation for a new slave device property > "sun4i,spi-wdelay" that allows to set the SPI Wait Clock Register per > device / transfer. The SPI hardware will wait the specified amount of > SPI clock periods (plus a constant 3 clock periods) before transmitting > the next word. > > The constant additional 3 clock periods are not documented by the vendor > and have been determined by analyzing the generated waveforms across > many different transmission speeds. > > Signed-off-by: Marcus Weseloh > --- > Documentation/devicetree/bindings/spi/spi-sun4i.txt | 11 +++++++++++ > drivers/spi/spi-sun4i.c | 7 +++++++ > 2 files changed, 18 insertions(+) > > diff --git a/Documentation/devicetree/bindings/spi/spi-sun4i.txt b/Documentation/devicetree/bindings/spi/spi-sun4i.txt > index de827f5..9c4d723 100644 > --- a/Documentation/devicetree/bindings/spi/spi-sun4i.txt > +++ b/Documentation/devicetree/bindings/spi/spi-sun4i.txt > @@ -10,6 +10,10 @@ Required properties: > - "mod": the parent module clock > - clock-names: Must contain the clock names described just above > > +Optional properties for slave devices: > +- sun4i,spi-wdelay : delay between transmission of words, specified in number > + of SPI clock periods (actual delay is wdelay + 3 clock periods) Seems like a common property to me. For a common one, it should be the actual delay and the driver needs to subtract the 3 clock periods here. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/