Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751632AbbHOEvy (ORCPT ); Sat, 15 Aug 2015 00:51:54 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:36700 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750806AbbHOEvx (ORCPT ); Sat, 15 Aug 2015 00:51:53 -0400 Message-ID: <55CEC567.109@wwwdotorg.org> Date: Fri, 14 Aug 2015 22:51:51 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: Eric Anholt CC: dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Lee Jones , devicetree@vger.kernel.org Subject: Re: [PATCH 6/7] ARM: bcm2835: Add the DDC I2C controller to the device tree. References: <1439427380-2436-1-git-send-email-eric@anholt.net> <1439427380-2436-7-git-send-email-eric@anholt.net> In-Reply-To: <1439427380-2436-7-git-send-email-eric@anholt.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 33 On 08/12/2015 06:56 PM, Eric Anholt wrote: > We need to use it for getting video modes over HDMI. > diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi > + i2c2: i2c@7e805000 { > + compatible = "brcm,bcm2835-i2c"; > + reg = <0x7e805000 0x1000>; > + interrupts = <2 21>; > + clocks = <&clk_i2c>; > + #address-cells = <1>; > + #size-cells = <0>; > + }; In an SoC .dtsi file, you'd typically write: status = "disabled"; ... in all nodes that represent IO controllers that interface to external HW, so that board DT files can/must explicitly choose to enable the device if it's actually in use on the board. Some systems might not have HDMI and hence might not hook up the HDMI_SCL/SDA pads. BCM2835-ARM-Peripherals.pdf states "Note that the BSC2 master is used dedicated with the HDMI interface and should not be accessed by user programs.". Does this imply the Linux kernel shouldn't be touching this I2C controller; that the VC4 firmware might also be attempting to use it? I wonder how any such sharing of the HW would work. -- 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/