Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756855AbbBEJp4 (ORCPT ); Thu, 5 Feb 2015 04:45:56 -0500 Received: from mail-pd0-f176.google.com ([209.85.192.176]:44490 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755355AbbBEJpv (ORCPT ); Thu, 5 Feb 2015 04:45:51 -0500 Message-ID: <54D33BC0.4050305@linaro.org> Date: Thu, 05 Feb 2015 17:45:36 +0800 From: Hanjun Guo User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Lorenzo Pieralisi CC: Catalin Marinas , "Rafael J. Wysocki" , Olof Johansson , Arnd Bergmann , Mark Rutland , "grant.likely@linaro.org" , Will Deacon , "graeme.gregory@linaro.org" , Sudeep Holla , "jcm@redhat.com" , Jason Cooper , Marc Zyngier , Bjorn Helgaas , Daniel Lezcano , Mark Brown , Rob Herring , Robert Richter , Randy Dunlap , Charles Garcia-Tobin , "phoenix.liyi@huawei.com" , Timur Tabi , Ashwin Chaugule , "suravee.suthikulpanit@amd.com" , Mark Langsdorf , "wangyijing@huawei.com" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" Subject: Re: [PATCH v8 09/21] ARM64 / ACPI: Disable ACPI if FADT revision is less than 5.1 References: <1422881149-8177-1-git-send-email-hanjun.guo@linaro.org> <1422881149-8177-10-git-send-email-hanjun.guo@linaro.org> <20150203172047.GA13339@e104818-lin.cambridge.arm.com> <54D1E891.80405@linaro.org> <20150204130626.GE22035@red-moon> In-Reply-To: <20150204130626.GE22035@red-moon> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4040 Lines: 105 On 2015年02月04日 21:06, Lorenzo Pieralisi wrote: > On Wed, Feb 04, 2015 at 09:38:25AM +0000, Hanjun Guo wrote: >> On 2015年02月04日 01:20, Catalin Marinas wrote: >>> On Mon, Feb 02, 2015 at 12:45:37PM +0000, Hanjun Guo wrote: >>>> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c >>>> index afe10b4..b9f64ec 100644 >>>> --- a/arch/arm64/kernel/acpi.c >>>> +++ b/arch/arm64/kernel/acpi.c >>>> @@ -13,6 +13,8 @@ >>>> * published by the Free Software Foundation. >>>> */ >>>> >>>> +#define pr_fmt(fmt) "ACPI: " fmt >>>> + >>>> #include >>>> #include >>>> #include >>>> @@ -49,10 +51,32 @@ void __init __acpi_unmap_table(char *map, unsigned long size) >>>> early_memunmap(map, size); >>>> } >>>> >>>> +static int __init acpi_parse_fadt(struct acpi_table_header *table) >>>> +{ >>>> + struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table; >>>> + >>>> + /* >>>> + * Revision in table header is the FADT Major revision, and there >>>> + * is a minor revision of FADT which was introduced by ACPI 5.1, >>>> + * we only deal with ACPI 5.1 or newer revision to get GIC and SMP >>>> + * boot protocol configuration data, or we will disable ACPI. >>>> + */ >>>> + if (table->revision > 5 || >>>> + (table->revision == 5 && fadt->minor_revision >= 1)) >>>> + return 0; >>>> + >>>> + pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n", >>>> + table->revision, fadt->minor_revision); >>>> + disable_acpi(); >>>> + >>>> + return -EINVAL; >>>> +} >>>> + >>>> /* >>>> * acpi_boot_table_init() called from setup_arch(), always. >>>> * 1. find RSDP and get its address, and then find XSDT >>>> * 2. extract all tables and checksums them all >>>> + * 3. check ACPI FADT revision >>>> * >>>> * We can parse ACPI boot-time tables such as MADT after >>>> * this function is called. >>>> @@ -64,8 +88,16 @@ void __init acpi_boot_table_init(void) >>>> return; >>>> >>>> /* Initialize the ACPI boot-time table parser. */ >>>> - if (acpi_table_init()) >>>> + if (acpi_table_init()) { >>>> + disable_acpi(); >>>> + return; >>>> + } >>>> + >>>> + if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) { >>>> + /* disable ACPI if no FADT is found */ >>>> disable_acpi(); >>>> + pr_err("Can't find FADT\n"); >>>> + } >>>> } >>> >>> It looks fine to call disable_acpi() here but a bit weird to call it >>> again in acpi_parse_fadt(). I guess that's because acpi_table_parse() >>> ignores the return value of the handler() call. I think it's better to >>> fix the core code (can be an additional patch on top of this series). >> >> I checked all the code calling acpi_table_parse() and I found that it >> will be no functional change if we return the value of handler(), but >> I need Rafael's confirm on it. > > Are you sure ? All calls to acpi_table_parse() that checks the return > value are affected. I guess that depends on what an error return from > the handler means, from acpi_table_parse(): > > * Return 0 if table found, -errno if not. Yes, you are right. What I mean for the "no functional change" because of most handler passed to acpi_table_parse() just return 0, I didn't describe it clearly, my bad. In ARM64 case, I find that we can not disable ACPI even if we return error for the handler, for example, we return -EOPNOTSUPP when there is no PSCI support, we can go on with cpu0 boot only. > > So, if table is found but parsing fails that acpi_table_parse() > signature should be changed if the handler barfs with an error and > it is propagated. Still, I share Catalin's comment. Sorry, I don't understand the last sentence, do you mean you agree with Catalin to return the result of handler()? Thanks Hanjun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/