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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 15B19C2D0E5 for ; Wed, 25 Mar 2020 20:34:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB41F20719 for ; Wed, 25 Mar 2020 20:34:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727395AbgCYUez (ORCPT ); Wed, 25 Mar 2020 16:34:55 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:39182 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727275AbgCYUez (ORCPT ); Wed, 25 Mar 2020 16:34:55 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id A8C712970B0 Subject: Re: [PATCH v2] platform: x86: Add ACPI driver for ChromeOS To: Srinivas Pandruvada , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, vbendeb@chromium.org, groeck@chromium.org, bleung@chromium.org, dtor@chromium.org, gwendal@chromium.org, andy@infradead.org, Collabora Kernel ML , Ayman Bagabas , Darren Hart , Dmitry Torokhov , Jeremy Soller , Mattias Jacobsson <2pi@mok.nu>, Mauro Carvalho Chehab , Rajat Jain , Yauhen Kharuzhy , platform-driver-x86@vger.kernel.org References: <20200322094334.1872663-1-enric.balletbo@collabora.com> <20200322111022.GA72939@kroah.com> <20200324164956.GE2518746@kroah.com> <3444110c-d6c0-16df-9b5d-12578ed442c5@collabora.com> <3166e472e0ef5c0db8da3ab7d846b47795e69057.camel@linux.intel.com> From: Enric Balletbo i Serra Message-ID: Date: Wed, 25 Mar 2020 21:34:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <3166e472e0ef5c0db8da3ab7d846b47795e69057.camel@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Srinivas, On 24/3/20 18:20, Srinivas Pandruvada wrote: > On Tue, 2020-03-24 at 18:08 +0100, Enric Balletbo i Serra wrote: >> Hi Greg, >> >> On 24/3/20 17:49, Greg Kroah-Hartman wrote: >>> On Tue, Mar 24, 2020 at 05:31:10PM +0100, Enric Balletbo i Serra >>> wrote: >>>> Hi Greg, >>>> >>>> Many thanks for your quick answer, some comments below. >>>> > [...] > >>> Are you sure they aren't already there under >>> /sys/firmware/acpi/? I >>> thought all tables and methods were exported there with no need to >>> do >>> anything special. >>> >> >> That's the first I did when I started to forward port this patch from >> chromeos >> kernel to mainline. >> >> On my system I get: >> >> /sys/firmware/acpi/tables# >> APIC DSDT FACP FACS HPET MCFG SSDT data dynamic >> >> (data and dynamic are empty directories) >> >> I quickly concluded (maybe wrong) that as there is no a MLST entry it >> was not >> exported, but maybe one of those already contains the info? Or, >> should I expect >> a MLST entry here? >> > If the data you are reading doesn't depend on any runtime variable in > ACPI tables then you can read from firmware tables as is. > > You can download acpica tools and run your method on acpi dump using > acpiexec tool. Once you can take dump, you can run on any Linux system. > > If you can get what you need from running on the dump, then you can do > by directly reading from /sys/firmware/acpi/tables/ from user space > without kernel change. Sometimes it is enough as lots of config data > tend to be static. > As I said I'm not an ACPI expert, so thanks in advance for your help. I am trying to look if I can get from userspace the value of the HWID entry exported from the driver. $ cat /sys/devices/platform/chromeos_acpi/HWID SAMUS E25-G7R-W35 Using acpiexec I get the element list of the MLST method, but I don't know how to get the HWID value. - evaluate crhw.mlst Evaluating \CRHW.MLST Evaluation of \CRHW.MLST returned object 0x55f17a7aed60, external buffer length 158 [Package] Contains 10 Elements: [String] Length 04 = "CHSW" [String] Length 04 = "FWID" [String] Length 04 = "HWID" [String] Length 04 = "FRID" [String] Length 04 = "BINF" [String] Length 04 = "GPIO" [String] Length 04 = "VBNV" [String] Length 04 = "VDAT" [String] Length 04 = "FMAP" [String] Length 04 = "MECK" Any clue? Thanks in advance, Enric > Thanks, > Srinivas > > > > > > >>> What makes these attributes "special" from any other ACPI method? >>> >> >> I can't answer this question right now. I need to investigate more I >> guess ;-) >> >> Thanks again for your answer, >> Enric >> >>>>>> +static int __init chromeos_acpi_init(void) >>>>>> +{ >>>>>> + int ret; >>>>>> + >>>>>> + chromeos_acpi.pdev = >>>>>> platform_device_register_simple("chromeos_acpi", >>>>>> + PLATFORM_DEVID_ >>>>>> NONE, NULL, 0); >>>>>> + if (IS_ERR(chromeos_acpi.pdev)) { >>>>>> + pr_err("unable to register chromeos_acpi >>>>>> platform device\n"); >>>>>> + return PTR_ERR(chromeos_acpi.pdev); >>>>>> + } >>>>> >>>>> Only use platform devices and drivers for things that are >>>>> actually >>>>> platform devices and drivers. That's not what this is, it is >>>>> an ACPI >>>>> device and driver. Don't abuse the platform interface please. >>>>> >>>> >>>> Ok. The purpose was to not break ChromeOS userspace since is >>>> looking for the >>>> attributes inside /sys/devices/platform/chromeos_acpi. Not a good >>>> reason, I >>>> know, and I assume we will need to change userspace instead, and >>>> convert this to >>>> a ACPI device and driver only, right? >>> >>> How can any userspace be looking for anything that hasn't been >>> submitted >>> before? That's nothing to worry about, we don't have to support >>> things >>> like that :) >>> >>>> I'll investigate the different places in userspace where this is >>>> used and see >>>> how difficult it is to do the changes. >>> >>> Look at /sys/firmware/acpi/ first please. >>> >>> thanks, >>> >>> greg k-h >>> > >