Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966506AbcKXUFe (ORCPT ); Thu, 24 Nov 2016 15:05:34 -0500 Received: from mail.blih.net ([212.83.177.182]:48607 "EHLO mail.blih.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753026AbcKXUFW (ORCPT ); Thu, 24 Nov 2016 15:05:22 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=bidouilliste.com; h=date :from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-type:content-transfer-encoding; q=dns; s= mail; b=m+JjKeNyXbONaamXcwTK3U/DDvCFiF8Hi7xuO4bxxJkqof5+d23FsuKK wzjxvhmMZ81A6r2ZXnt75mEXqdfTM3eqs74CHTJJh4JwKAWs4DAmXmWbpnZxWFUe t7QNv+u4OcbKpzdiJAjEsskvlSL72sfMt0x/Xl9kCDriusI4w/k= Date: Thu, 24 Nov 2016 21:05:09 +0100 From: Emmanuel Vadot To: Maxime Ripard Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux@armlinux.org.uk, linux-kernel@vger.kernel.org, wens@csie.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ARM: dts: sunxi: Add num-cs for A20 spi nodes Message-Id: <20161124210509.be743aae84c26c6c2e666c6e@bidouilliste.com> In-Reply-To: <20161124195517.qrq7briu3pwjnp4n@lukather> References: <20161122170616.29557-1-manu@bidouilliste.com> <20161124195517.qrq7briu3pwjnp4n@lukather> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.29; amd64-portbld-freebsd12.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 926 Lines: 32 On Thu, 24 Nov 2016 20:55:17 +0100 Maxime Ripard wrote: > On Tue, Nov 22, 2016 at 06:06:16PM +0100, Emmanuel Vadot wrote: > > The spi0 controller on the A20 have up to 4 CS (Chip Select) while the > > others three only have 1. > > Add the num-cs property to each node. > > > > Signed-off-by: Emmanuel Vadot > > I don't think we have any code that uses it at the moment. What is the > rationale behind this patch? > > Thanks! > Maxime > > -- > Maxime Ripard, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com Hi Maxime, If num-cs isn't present nothing prevent to start a transfer with a non-valid CS pin, resulting in an error. num-cs are default property especially made for this and a SPI driver should try to get the property at probe/attach time. Cheers, -- Emmanuel Vadot