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Message-ID: <53F33EDC.3090203@linaro.org>
Date: Tue, 19 Aug 2014 20:11:08 +0800
From: Hanjun Guo <hanjun.guo@...aro.org>
To: Geoff Levand <geoff@...radead.org>
CC: Catalin Marinas <catalin.marinas@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Mark Rutland <mark.rutland@....com>,
linaro-acpi@...ts.linaro.org, Liviu Dudau <Liviu.Dudau@....com>,
Lv Zheng <lv.zheng@...el.com>, Rob Herring <robh@...nel.org>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Robert Moore <robert.moore@...el.com>,
linux-acpi@...r.kernel.org, Grant Likely <grant.likely@...aro.org>,
Charles.Garcia-Tobin@....com, Robert Richter <rric@...nel.org>,
Jason Cooper <jason@...edaemon.net>,
Arnd Bergmann <arnd@...db.de>,
Marc Zyngier <marc.zyngier@....com>,
Will Deacon <will.deacon@....com>,
Tomasz Nowicki <tomasz.nowicki@...aro.org>,
Mark Brown <broonie@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
linux-arm-kernel@...ts.infradead.org,
Graeme Gregory <graeme.gregory@...aro.org>,
Randy Dunlap <rdunlap@...radead.org>,
linux-kernel@...r.kernel.org, Sudeep Holla <Sudeep.Holla@....com>,
Olof Johansson <olof@...om.net>
Subject: Re: [PATCH v2 08/18] ARM64 / ACPI: Get the enable method for SMP
initialization in ACPI way
On 2014-8-19 2:56, Geoff Levand wrote:
> Hi Hanjun,
Hi Geoff,
>
> On Mon, 2014-08-04 at 23:28 +0800, Hanjun Guo wrote:
>> --- a/arch/arm64/include/asm/acpi.h
>> +++ b/arch/arm64/include/asm/acpi.h
>> @@ -14,6 +14,27 @@
>>
>> /* Basic configuration for ACPI */
>> #ifdef CONFIG_ACPI
>
> By having this preprocessor conditional in the header leads
> to a proliferation of preprocessor conditionals since any
> code that includes this header will also need to have
> preprocessor conditionals. Another down side of having
> this is that this code will not get a build test for
> builds with CONFIG_ACPI=n.
I will move some definitions out of preprocessor conditional and
introduce some stub function when CONFIG_ACPI is disabled, then
I think I can remove all the preprocessor conditionals in .c file.
>
>> +/*
>> + * ACPI 5.1 only has two explicit methods to
>> + * boot up SMP, PSCI and Parking protocol,
>> + * but the Parking protocol is only defined
>> + * for ARMv7 now, so make PSCI as the only
>> + * way for the SMP boot protocol before some
>> + * updates for the ACPI spec or the Parking
>> + * protocol spec.
>> + *
>> + * This enum is intend to make the boot method
>> + * scalable when above updates are happended,
>> + * which NOT means to support all of them.
>> + */
>> +enum acpi_smp_boot_protocol {
>> + ACPI_SMP_BOOT_PSCI,
>> + ACPI_SMP_BOOT_PARKING_PROTOCOL,
>> + ACPI_SMP_BOOT_PROTOCOL_MAX
>> +};
>> +
>> +enum acpi_smp_boot_protocol smp_boot_protocol(void);
>
> The name smp_boot_protocol() seems like it would be a generic
> routine, but it is acpi specific. Maybe:
>
> enum acpi_boot_protocol_type {...};
>
> enum acpi_boot_protocol_type acpi_boot_protocol(void);
Agreed.
>
>> --- a/arch/arm64/kernel/cpu_ops.c
>> +++ b/arch/arm64/kernel/cpu_ops.c
>> @@ -49,12 +51,44 @@ static const struct cpu_operations * __init cpu_get_ops(const char *name)
>> return NULL;
>> }
>>
>> +#ifdef CONFIG_ACPI
>> +/*
>> + * Get a cpu's boot method in the ACPI way.
>> + */
>> +static char * __init acpi_get_cpu_boot_method(void)
>> +{
>> + /*
>> + * For ACPI 5.1, only two kind of methods are provided,
>> + * Parking protocol and PSCI, but Parking protocol is
>> + * specified for ARMv7 only, so make PSCI as the only method
>> + * for SMP initialization before the ACPI spec or Parking
>> + * protocol spec is updated.
>> + */
>> + switch (smp_boot_protocol()) {
>> + case ACPI_SMP_BOOT_PSCI:
>> + return "psci";
>> + case ACPI_SMP_BOOT_PARKING_PROTOCOL:
>> + default:
>> + return NULL;
>> + }
>> +}
>> +#else
>> +static inline char * __init acpi_get_cpu_boot_method(void) { return NULL; }
>> +#endif
>
> Since this is inside a C source file, the inline keyword
> isn't needed since the optimizer will inline regardless.
>
> With that said, I think it would be cleaner to have this
> as:
>
> static char * __init acpi_get_cpu_boot_method(void)
> {
> #ifdef CONFIG_ACPI
> return NULL;
> #else
> ...
> #endif
> }
>
> Or better to make smp_boot_protocol() callable regardless
> of CONFIG_ACPI and then no preprocessor conditionals at all
> would be needed.
>
>> +
>> /*
>> - * Read a cpu's enable method from the device tree and record it in cpu_ops.
>> + * Read a cpu's enable method and record it in cpu_ops.
>> */
>> int __init cpu_read_ops(struct device_node *dn, int cpu)
>> {
>> - const char *enable_method = of_get_property(dn, "enable-method", NULL);
>> + const char *enable_method;
>> +
>> + if (!acpi_disabled) {
>> + enable_method = acpi_get_cpu_boot_method();
>> + goto get_ops;
>> + }
>> +
>> + enable_method = of_get_property(dn, "enable-method", NULL);
>> if (!enable_method) {
>> /*
>> * The boot CPU may not have an enable method (e.g. when
>> @@ -66,10 +100,17 @@ int __init cpu_read_ops(struct device_node *dn, int cpu)
>> return -ENOENT;
>> }
>>
>> +get_ops:
>> cpu_ops[cpu] = cpu_get_ops(enable_method);
>> if (!cpu_ops[cpu]) {
>> - pr_warn("%s: unsupported enable-method property: %s\n",
>> - dn->full_name, enable_method);
>> + if (acpi_disabled) {
>> + pr_warn("%s: unsupported enable-method property: %s\n",
>> + dn->full_name, enable_method);
>> + } else {
>> + pr_warn("CPU %d: boot protocol unsupported or unknown\n",
>> + cpu);
>> + }
>> +
>
> Can't we have this more integrated, maybe something like this?
>
> enable_method = acpi_disabled ? of_get_property(dn, "enable-method", NULL)
> : acpi_get_cpu_boot_method();
I like this :)
> message = acpi_disabled ? dn->full_name : "";
>
> ...
>
> pr_warn("CPU %d: %s unsupported enable-method property: %s\n",
> cpu, message, enable_method)
In ACPI, there is no enable-method property, it is a term from, so I think the
message printed can be separated.
Thanks
Hanjun
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