From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751247AbdBABOu (ORCPT ); Tue, 31 Jan 2017 20:14:50 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:37730 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750969AbdBABOr (ORCPT ); Tue, 31 Jan 2017 20:14:47 -0500 Date: Wed, 1 Feb 2017 01:13:49 +0000 From: Russell King - ARM Linux To: Steve Longerbeam Cc: Philipp Zabel , robh+dt@kernel.org, mark.rutland@arm.com, shawnguo@kernel.org, kernel@pengutronix.de, fabio.estevam@nxp.com, mchehab@kernel.org, hverkuil@xs4all.nl, nick@shmanahar.org, markus.heiser@darmarIT.de, laurent.pinchart+renesas@ideasonboard.com, bparrot@ti.com, geert@linux-m68k.org, arnd@arndb.de, sudipm.mukherjee@gmail.com, minghsiu.tsai@mediatek.com, tiffany.lin@mediatek.com, jean-christophe.trotin@st.com, horms+renesas@verge.net.au, niklas.soderlund+renesas@ragnatech.se, robert.jarzmik@free.fr, songjun.wu@microchip.com, andrew-ct.chen@mediatek.com, gregkh@linuxfoundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org, devel@driverdev.osuosl.org, Steve Longerbeam Subject: Re: [PATCH v3 21/24] media: imx: Add MIPI CSI-2 Receiver subdev driver Message-ID: <20170201011349.GJ27312@n2100.armlinux.org.uk> References: <1483755102-24785-1-git-send-email-steve_longerbeam@mentor.com> <1483755102-24785-22-git-send-email-steve_longerbeam@mentor.com> <20170131000125.GO27312@n2100.armlinux.org.uk> <1485856160.2932.10.camel@pengutronix.de> <6e77aefa-4f22-60e9-7cc0-55c3a2de3124@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6e77aefa-4f22-60e9-7cc0-55c3a2de3124@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 Hi Steve, On Tue, Jan 31, 2017 at 05:02:40PM -0800, Steve Longerbeam wrote: > But this also puts a requirement on MIPI sensors that s_power(ON) > should only place the D_PHY in LP-11, and _not_ start the clock lane. > But perhaps that is correct behavior anyway. If the CSI2 DPHY is held in reset state, it shouldn't matter what the sensor does. In the case of IMX219, it needs a full setup of the device, including enabling it to stream (so it starts the clock lane etc) in order to get it into LP-11 state. Merely disabling the XCLR signal leaves the lanes grounded. I do seem to remember reading in one of the MIPI specs that this is rather expected behaviour, though I can't point at a paragraph this late in the night. So, the only way to satisfy these requirements is this order: - assert PHY reset signals (so blocking any activity on the CSI lanes) - initialise the sensor (including allowing it to start streaming and then stopping the stream - at that point, the lanes will be in LP-11.) - deassert the resets as per the iMX6 documentation and follow the remaining procedure. I'll look at your other points tomorrow. Thanks. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.