From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Linton Subject: Re: [PATCH 4/4] perf: arm_spe: Enable ACPI/Platform automatic module loading Date: Thu, 25 Apr 2019 19:58:28 -0500 Message-ID: <1345818a-3a4a-e919-2168-e2950cee07b6@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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190416135055.GA3313@fuggles.cambridge.arm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon 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 List-Id: linux-acpi@vger.kernel.org Hi, 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. >> >>> >>>> + { } >>>> +}; >>>> +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: 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. 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. *(interestingly trivia: There doesn't appear to be a single arm64 module which matches on a MODULE_TABLE OF name. They only match type or compatible. Out of the 3534 modules on my machine only three do any OF table type matching, ipmi_si and two drivers for freescale networking fsl_pq_mdio and gianfar_driver. In those cases, i'm not even sure its actually necessary.) 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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 49030C43218 for ; Fri, 26 Apr 2019 00:58:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 27346206BA for ; Fri, 26 Apr 2019 00:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730467AbfDZA6f (ORCPT ); Thu, 25 Apr 2019 20:58:35 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:57104 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbfDZA6f (ORCPT ); Thu, 25 Apr 2019 20:58:35 -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 69AA680D; Thu, 25 Apr 2019 17:58:34 -0700 (PDT) Received: from [192.168.100.241] (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AD0313F246; Thu, 25 Apr 2019 17:58:33 -0700 (PDT) Subject: Re: [PATCH 4/4] perf: arm_spe: Enable ACPI/Platform automatic module loading To: Will Deacon 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 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> From: Jeremy Linton Message-ID: <1345818a-3a4a-e919-2168-e2950cee07b6@arm.com> Date: Thu, 25 Apr 2019 19:58:28 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190416135055.GA3313@fuggles.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Message-ID: <20190426005828.rFG1sq7JnBBd-F2LJdl5h0qF2lmsfJa-NVZKC2_6oxE@z> Hi, 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. >> >>> >>>> + { } >>>> +}; >>>> +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: 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. 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. *(interestingly trivia: There doesn't appear to be a single arm64 module which matches on a MODULE_TABLE OF name. They only match type or compatible. Out of the 3534 modules on my machine only three do any OF table type matching, ipmi_si and two drivers for freescale networking fsl_pq_mdio and gianfar_driver. In those cases, i'm not even sure its actually necessary.)