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Message-ID: <53F3346D.7080404@linaro.org>
Date: Tue, 19 Aug 2014 19:26:37 +0800
From: Hanjun Guo <hanjun.guo@...aro.org>
To: Sudeep Holla <sudeep.holla@....com>,
Mark Rutland <Mark.Rutland@....com>
CC: Catalin Marinas <Catalin.Marinas@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
"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@...nel.org>, Rob Herring <robh@...nel.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>,
"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
Tomasz Nowicki <tomasz.nowicki@...aro.org>
Subject: Re: [PATCH v2 08/18] ARM64 / ACPI: Get the enable method for SMP
initialization in ACPI way
On 2014-8-19 2:34, Sudeep Holla wrote:
> On 04/08/14 16:28, Hanjun Guo wrote:
[...]
>> /* Basic configuration for ACPI */
>> #ifdef CONFIG_ACPI
>> +/*
>> + * 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);
>> +
[...]
>> +/* Protocol to bring up secondary CPUs */
>> +enum acpi_smp_boot_protocol smp_boot_protocol(void)
>> +{
>> + if (acpi_psci_present())
>> + return ACPI_SMP_BOOT_PSCI;
>> + else
>> + return ACPI_SMP_BOOT_PARKING_PROTOCOL;
>> +}
>> +
>
> Which do you need this here ? Can't you use acpi_psci_present directly
> in acpi_get_cpu_boot_method ?
My intent was to make the code scalable if we introduce another (or more)
boot protocol in ACPI, does it make sense to you?
>
>> static int __init acpi_parse_fadt(struct acpi_table_header *table)
>> {
>> struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
>> diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
>> index d62d12f..05bc314 100644
>> --- a/arch/arm64/kernel/cpu_ops.c
>> +++ b/arch/arm64/kernel/cpu_ops.c
>> @@ -16,11 +16,13 @@
>> * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> */
>>
>> -#include <asm/cpu_ops.h>
>> -#include <asm/smp_plat.h>
>> #include <linux/errno.h>
>> #include <linux/of.h>
>> #include <linux/string.h>
>> +#include <linux/acpi.h>
>> +
>> +#include <asm/cpu_ops.h>
>> +#include <asm/smp_plat.h>
>>
>> extern const struct cpu_operations smp_spin_table_ops;
>> extern const struct cpu_operations cpu_psci_ops;
>> @@ -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;
>> + }
>
> Use acpi_psci_present as mentioned above.
>
>> +}
>> +#else
>> +static inline char * __init acpi_get_cpu_boot_method(void) { return NULL; }
>> +#endif
>> +
>> /*
>> - * 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);
>> + }
>> +
>> return -EOPNOTSUPP;
>> }
>>
>> @@ -78,7 +119,14 @@ int __init cpu_read_ops(struct device_node *dn, int cpu)
>>
>> void __init cpu_read_bootcpu_ops(void)
>> {
>> - struct device_node *dn = of_get_cpu_node(0, NULL);
>> + struct device_node *dn;
>> +
>> + if (!acpi_disabled) {
>> + cpu_read_ops(NULL, 0);
>> + return;
>> + }
>> +
>
> Again not good to mix ACPI in DT functions forcing you to pass
> device_node ptr as NULL, better to separate this.
I separate them in the first version, and combine tham as Geoff suggested
for scalable reasons.
> Once you gather all
> this !acpi_disabled case, you can create appropriate abstractions to be
> used in setup.c
>
> E.g. here you check !acpi_disabled and pass NULL for DT node to
> cpu_read_ops and hence again you check for !acpi_disabled in
> cpu_read_ops. So you need first identify all these checks and put in one
> place to understand well how you can refactor existing code to avoid
> these multiple checks.
I will remove the multiple acpi_disabled checks and refactor the code.
Thanks
Hanjun
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