From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00662C64E90 for ; Tue, 1 Dec 2020 12:45:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A08342084C for ; Tue, 1 Dec 2020 12:45:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389118AbgLAMpw (ORCPT ); Tue, 1 Dec 2020 07:45:52 -0500 Received: from retiisi.eu ([95.216.213.190]:47610 "EHLO hillosipuli.retiisi.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387954AbgLAMpv (ORCPT ); Tue, 1 Dec 2020 07:45:51 -0500 X-Greylist: delayed 21583 seconds by postgrey-1.27 at vger.kernel.org; Tue, 01 Dec 2020 07:45:50 EST Received: from valkosipuli.localdomain (unknown [IPv6:fd35:1bc8:1a6:d3d5::80:2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by hillosipuli.retiisi.eu (Postfix) with ESMTPS id 347E2634C87; Tue, 1 Dec 2020 14:44:02 +0200 (EET) Received: from sailus by valkosipuli.localdomain with local (Exim 4.92) (envelope-from ) id 1kk50k-0002qX-Ki; Tue, 01 Dec 2020 14:44:02 +0200 Date: Tue, 1 Dec 2020 14:44:02 +0200 From: Sakari Ailus To: Laurent Pinchart Cc: Dan Scally , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org, linux-media@vger.kernel.org, devel@acpica.org, rjw@rjwysocki.net, lenb@kernel.org, gregkh@linuxfoundation.org, mika.westerberg@linux.intel.com, andriy.shevchenko@linux.intel.com, linus.walleij@linaro.org, bgolaszewski@baylibre.com, wsa@kernel.org, yong.zhi@intel.com, sakari.ailus@linux.intel.com, bingbu.cao@intel.com, tian.shu.qiu@intel.com, mchehab@kernel.org, robert.moore@intel.com, erik.kaneda@intel.com, pmladek@suse.com, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, linux@rasmusvillemoes.dk, kieran.bingham+renesas@ideasonboard.com, jacopo+renesas@jmondi.org, laurent.pinchart+renesas@ideasonboard.com, jorhand@linux.microsoft.com, kitakar@gmail.com, heikki.krogerus@linux.intel.com Subject: Re: [PATCH 18/18] ipu3: Add driver for dummy INT3472 ACPI device Message-ID: <20201201124402.GU4351@valkosipuli.retiisi.org.uk> References: <20201130133129.1024662-1-djrscally@gmail.com> <20201130133129.1024662-19-djrscally@gmail.com> <20201130205203.GQ4351@valkosipuli.retiisi.org.uk> <3e8494a0-a2c0-59e7-46bb-9635c3c239dd@gmail.com> <20201201064421.GR4351@valkosipuli.retiisi.org.uk> <2a548835-78c6-8fe3-cceb-1fc000707157@gmail.com> <20201201123244.GT4351@valkosipuli.retiisi.org.uk> <20201201124032.GD4569@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201201124032.GD4569@pendragon.ideasonboard.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 01, 2020 at 02:40:32PM +0200, Laurent Pinchart wrote: > Hi Sakari, > > On Tue, Dec 01, 2020 at 02:32:44PM +0200, Sakari Ailus wrote: > > On Tue, Dec 01, 2020 at 08:08:26AM +0000, Dan Scally wrote: > > > On 01/12/2020 06:44, Sakari Ailus wrote: > > > > On Mon, Nov 30, 2020 at 11:06:03PM +0000, Dan Scally wrote: > > > >> On 30/11/2020 20:52, Sakari Ailus wrote: > > > >>>> +static const struct acpi_device_id int3472_device_id[] = { > > > >>>> + { "INT3472", 0 }, > > > >>> > > > >>> The INT3472 _HID is really allocated for the tps68470 PMIC chip. It may not > > > >>> be used by other drivers; people will want to build kernels where both of > > > >>> these ACPI table layouts are functional. > > > >>> > > > >>> Instead, I propose, that you add this as an option to the tps68470 driver > > > >>> that figures out whether the ACPI device for the tps68470 device actually > > > >>> describes something else, in a similar fashion you do with the cio2-bridge > > > >>> driver. I think it may need a separate Kconfig option albeit this and > > > >>> cio2-bridge cannot be used separately. > > > >> > > > >> It actually occurs to me that that may not work (I know I called that > > > >> out as an option we considered, but that was a while ago actually). The > > > >> reason I wasn't worried about the existing tps68470 driver binding to > > > >> these devices is that it's an i2c driver, and these dummy devices don't > > > >> have an I2cSerialBusV2, so no I2C device is created by them the kernel. > > > >> > > > >> Won't that mean the tps68470 driver won't ever be probed for these devices? > > > > > > > > Oops. I missed this indeed was not an I²C driver. So please ignore the > > > > comment. > > > > > > > > So I guess this wouldn't be an actual problem. I'd still like to test this > > > > on a system with tps68470, as the rest of the set. > > > > > > On my Go2, it .probes() for the actual tps68740 (that machine has both > > > types of INT3472 device) but fails with EINVAL when it can't find the > > > CLDB buffer that these discrete type devices have. My understanding is > > > that means it's free for the actual tps68470 driver to grab the device; > > > although that's not happening because I had to blacklist that driver or > > > it stops the machine from booting at the moment - haven't gotten round > > > to investigating yet. > > > > Oh, then the problem is actually there. If it probes the tps68470 driver on > > the systems with Windows ACPI tables, then it should be that driver which > > works with the Windows ACPI tables, too. > > > > Checking for random objects such as CLDB in multiple drivers and returning > > an error based on them being there or not wouldn't be exactly neat. > > Although I'm not sure thare are options that are obviosly pretty here. I > > wouldn't two separate drivers checking for e.g. CLDB (tps68470 + this one). > > > > The tps68470 driver is an MFD driver that instantiates a number of platform > > devices. Alternatively, if you make this one a platform device, you can, in > > case the CLDB (or whatever object) is present, in the tps68470 driver > > instantiate a device for this driver instead of the rest. > > > > So I'd think what matters is that both drivers can be selected at the same > > time but the user does not need to manually select them. Both ways could > > work I guess? > > Let's make it simpler instead of creating lots of devices. Here's what > I've proposed in a different e-mail in this thread. > > > Given that INT3472 means Intel camera power management device (that's > > more or less the wording in Windows, I can double-check), would the > > following make sense ? > > > > A top-level module named intel-camera-pmic (or int3472, or ...) would > > register two drivers, a platform driver and an I2C driver, to > > accommodate for both cases ("discrete PMIC" that doesn't have an > > I2cSerialBusV2, and TPS64870 or uP6641Q that are I2C devices). The probe > > function would perform the following: > > > > - If there's no CLDB, then the device uses the Chrome OS "ACPI > > bindings", and refers to a TPS64870. The code that exists in the > > kernel today (registering GPIOs, and registering an OpRegion to > > communicate with the power management code in the DSDT) would be > > activated. > > > > - If there's a CLDB, then the device type would be retrieved from it: > > > > - If the device is a "discrete PMIC", the driver would register clocks > > and regulators controlled by GPIOs, and create clock, regulator and > > GPIO lookup entries for the sensor device that references the PMIC. > > > > - If the device is a TPS64870, the code that exists in the kernel > > today to register GPIOs would be activated, and new code would need > > to be written to register regulators and clocks. > > > > - If the device is a uP6641Q, a new driver will need to be written (I > > don't know on which devices this PMIC is used, so this can probably > > be deferred). > > > > We can split this in multiple files and/or modules. > > Could you reply to 20201130233232.GD25713@pendragon.ideasonboard.com to > avoid splitting the conversation ? Yeah... I hadn't gotten that far yet. :-) -- Sakari Ailus