From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933740AbdBQLHX (ORCPT ); Fri, 17 Feb 2017 06:07:23 -0500 Received: from pandora.armlinux.org.uk ([78.32.30.218]:55554 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932491AbdBQLHU (ORCPT ); Fri, 17 Feb 2017 06:07:20 -0500 Date: Fri, 17 Feb 2017 11:06:16 +0000 From: Russell King - ARM Linux To: Philipp Zabel Cc: Steve Longerbeam , 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, shuah@kernel.org, sakari.ailus@linux.intel.com, pavel@ucw.cz, 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 v4 23/36] media: imx: Add MIPI CSI-2 Receiver subdev driver Message-ID: <20170217110616.GD21222@n2100.armlinux.org.uk> References: <1487211578-11360-1-git-send-email-steve_longerbeam@mentor.com> <1487211578-11360-24-git-send-email-steve_longerbeam@mentor.com> <1487328479.3107.21.camel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1487328479.3107.21.camel@pengutronix.de> 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 On Fri, Feb 17, 2017 at 11:47:59AM +0100, Philipp Zabel wrote: > On Wed, 2017-02-15 at 18:19 -0800, Steve Longerbeam wrote: > > +static void csi2_dphy_init(struct csi2_dev *csi2) > > +{ > > + /* > > + * FIXME: 0x14 is derived from a fixed D-PHY reference > > + * clock from the HSI_TX PLL, and a fixed target lane max > > + * bandwidth of 300 Mbps. This value should be derived > > If the table in https://community.nxp.com/docs/DOC-94312 is correct, > this should be 850 Mbps. Where does this 300 Mbps value come from? I thought you had some code to compute the correct value, although I guess we've lost the ability to know how fast the sensor is going to drive the link. Note that the IMX219 currently drives the data lanes at 912Mbps almost exclusively, as I've yet to finish working out how to derive the PLL parameters. (I have something that works, but it currently takes on the order of 100k iterations to derive the parameters. gcd() doesn't help you in this instance.) -- 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.