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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 500BDC43218 for ; Fri, 26 Apr 2019 08:04:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B7A9206BA for ; Fri, 26 Apr 2019 08:04:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725985AbfDZIEy (ORCPT ); Fri, 26 Apr 2019 04:04:54 -0400 Received: from foss.arm.com ([217.140.101.70]:34962 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725854AbfDZIEy (ORCPT ); Fri, 26 Apr 2019 04:04:54 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6D7C2A78; Fri, 26 Apr 2019 01:04:53 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 37B133F246; Fri, 26 Apr 2019 01:04:51 -0700 (PDT) Date: Fri, 26 Apr 2019 09:04:45 +0100 From: Will Deacon To: Jeremy Linton Cc: linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, rjw@rjwysocki.net, lenb@kernel.org, mark.rutland@arm.com, sudeep.holla@arm.com, james.morse@arm.com, lorenzo.pieralisi@arm.com, linuxarm@huawei.com Subject: Re: [PATCH 4/4] perf: arm_spe: Enable ACPI/Platform automatic module loading Message-ID: <20190426080445.GA28144@fuggles.cambridge.arm.com> References: <20190326223938.5365-1-jeremy.linton@arm.com> <20190326223938.5365-5-jeremy.linton@arm.com> <20190404170423.GC28932@fuggles.cambridge.arm.com> <065cc8ae-f2c0-e493-b0a6-5c7340db37f5@arm.com> <20190416135055.GA3313@fuggles.cambridge.arm.com> <1345818a-3a4a-e919-2168-e2950cee07b6@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1345818a-3a4a-e919-2168-e2950cee07b6@arm.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 25, 2019 at 07:58:28PM -0500, Jeremy Linton wrote: > On 4/16/19 8:50 AM, Will Deacon wrote: > > On Thu, Apr 04, 2019 at 12:24:38PM -0500, Jeremy Linton wrote: > > > On 4/4/19 12:04 PM, Will Deacon wrote: > > > > On Tue, Mar 26, 2019 at 05:39:38PM -0500, Jeremy Linton wrote: > > > > > Lets add the MODULE_TABLE and platform id_table entries so that > > > > > the SPE driver can attach to the ACPI platform device created by > > > > > the core pmu code. > > > > > > > > > > Signed-off-by: Jeremy Linton > > > > > Reviewed-by: Sudeep Holla > > > > > --- > > > > > drivers/perf/arm_spe_pmu.c | 11 +++++++++-- > > > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > > > > > index 7cb766dafe85..ffa2c76c08bb 100644 > > > > > --- a/drivers/perf/arm_spe_pmu.c > > > > > +++ b/drivers/perf/arm_spe_pmu.c > > > > > @@ -1176,7 +1176,13 @@ static const struct of_device_id arm_spe_pmu_of_match[] = { > > > > > }; > > > > > MODULE_DEVICE_TABLE(of, arm_spe_pmu_of_match); > > > > > -static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev) > > > > > +static const struct platform_device_id arm_spe_match[] = { > > > > > + { "arm,spe-v1", 0}, > > > > > > > > It would be nice if we could avoid duplicating this string from the ACPI > > > > parsing code. > > > > > > Ok sure, I just need to find a good common place for it. > > There doesn't appear to be a good common place for this, so maybe arm_pmu.h, > which can then be included in the spe driver is the right thing. I'm fine with that. > > > > > + { } > > > > > +}; > > > > > +MODULE_DEVICE_TABLE(platform, arm_spe_match); > > > > > + > > > > > +static int arm_spe_pmu_device_probe(struct platform_device *pdev) > > > > > { > > > > > int ret; > > > > > struct arm_spe_pmu *spe_pmu; > > > > > @@ -1236,11 +1242,12 @@ static int arm_spe_pmu_device_remove(struct platform_device *pdev) > > > > > } > > > > > static struct platform_driver arm_spe_pmu_driver = { > > > > > + .id_table = arm_spe_match, > > > > > .driver = { > > > > > .name = DRVNAME, > > > > > .of_match_table = of_match_ptr(arm_spe_pmu_of_match), > > > > > > > > Hmm, so some other drivers don't hook .id_table like you do, but instead > > > > hook .acpi_match_table in the driver structure. Is that not better? > > > > > > This isn't actually an ACPI device, (aka not defined in the namespace), so > > > its missing much of the ACPI functionality. I think that also means its > > > needs to be declared this way. > > > > Looking at platform_match(), I'd really like to avoid having both an > > .id_table and an .of_match_table field. > > > > > > acpi_of_match_device() will actually use the .of_match_table, but it relies > > on ACPI_COMPANION returning a valid acpi_device. If we don't have one of > > Right, via the fwnode it can cause an acpi DSDT defined device with a _DSD > "compatible" property to match an entry in the of_match_table compatible > string. I don't think this is us... > > > those, perhaps we can use the .id_table exclusively and drop the > > .of_match_table instead? > > This definitely made me do my homework, the following is AFAIK: FWIW: I'm also feeling my way here! > Its possible to match on just a .id_table, but this requires matching the OF > device name against the id_table name rather than against the OF compatible > string (*). This doesn't seem like a good idea, despite platform_device_id > entries being significantly smaller than the of_device_id ones. Plus, I > think we end up with two duplicate tables because we still need the > MODULE_TABLE(of,xxx) to assure that userspace can associate the modalias > with the module. Well spotted, I didn't notice that the compatible string isn't used for matching in that case. > OTOH, it seems possible to match on module name directly ('arm_spe_pmu'), > but this limits us to only a single device type for all ACPI device > variations unless we put platform checks in the module itself (ick!). I > suspect in the future if a spe.v2 were to come out this would be a problem > unless a separate module were created. Then there is the fact this still > needs a platform_device_id table, as the modalias will read > "platform:arm_spe_pmu". Which will cause people to question why its not just > assigned and matched against the .id_table. Ok, fair enough and sorry for the wild goose chase. Looks like we'll stick with what you had, as the alternatives all seen considerably worse. Will