linux-kernel - Re: [PATCH v8 09/21] ARM64 / ACPI: Disable ACPI if FADT revision is less than 5.1

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Date:	Wed, 04 Feb 2015 17:38:25 +0800
From:	Hanjun Guo <hanjun.guo@...aro.org>
To:	Catalin Marinas <catalin.marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
	Mark Rutland <Mark.Rutland@....com>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Will Deacon <Will.Deacon@....com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
	Sudeep Holla <Sudeep.Holla@....com>,
	"jcm@...hat.com" <jcm@...hat.com>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <Marc.Zyngier@....com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
	Robert Richter <rric@...nel.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
	"phoenix.liyi@...wei.com" <phoenix.liyi@...wei.com>,
	Timur Tabi <timur@...eaurora.org>,
	Ashwin Chaugule <ashwinc@...eaurora.org>,
	"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
	Mark Langsdorf <mlangsdo@...hat.com>,
	"wangyijing@...wei.com" <wangyijing@...wei.com>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH v8 09/21] ARM64 / ACPI: Disable ACPI if FADT revision
 is less than 5.1

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 <linux/acpi.h>
>>   #include <linux/bootmem.h>
>>   #include <linux/cpumask.h>
>> @@ -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.

Thanks
Hanjun
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