linux-kernel - Re: [PATCH 06/19] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init

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Date:	Thu, 31 Jul 2014 11:53:14 +0800
From:	Hanjun Guo <hanjun.guo@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Mark Rutland <Mark.Rutland@....com>
CC:	"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
	Arnd Bergmann <arnd@...db.de>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Will Deacon <Will.Deacon@....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@...aro.org>,
	Robert Richter <rric@...nel.org>,
	Lv Zheng <lv.zheng@...el.com>,
	Robert Moore <robert.moore@...el.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Liviu Dudau <Liviu.Dudau@....com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Charles Garcia-Tobin <Charles.Garcia-Tobin@....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>
Subject: Re: [PATCH 06/19] ARM64 / ACPI: Parse FADT table to get PSCI flags
 for PSCI init

On 2014-7-30 0:40, Sudeep Holla wrote:
[...]
>>
>> +/* 1 to indicate PSCI is implemented */
>> +int acpi_psci_present;
>> +
>> +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
>> +int acpi_psci_use_hvc;
>> +
> 
> These can be boolean but can be removed IMO, see below.
> 
>>   /*
>>    * __acpi_map_table() will be called before page_init(), so early_ioremap()
>>    * or early_memremap() should be called here to for ACPI table mapping.
>> @@ -54,6 +62,33 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
>>       early_iounmap(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 version,
>> +     * and there is a minor version of FADT which was introduced
>> +     * by ACPI 5.1, we only deal with ACPI 5.1 or higher version
>> +     * to get arm boot flags, or we will disable ACPI.
>> +     */
>> +    if (table->revision < 5 || fadt->minor_version < 1) {
>> +        pr_info("FADT version is %d.%d, no PSCI support, should be 5.1 or
>> higher\n",
>> +            table->revision, fadt->minor_version);
>> +        acpi_psci_present = 0;
>> +        disable_acpi();
>> +        return -EINVAL;
>> +    }
>> +
>> +    if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT)
>> +        acpi_psci_present = 1;
>> +
>> +    if (acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
>> +        acpi_psci_use_hvc = 1;
>> +
> 
> Why not make this macros instead of global variables as I suggested in
> previous version. acpi_gbl_FADT is already global and you can avoid
> creating new one especially they are just used on boot/init.

Ok, it makes sense to me, I will update it in next version.

Thanks
Hanjun

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