Messages in this thread | | | Date | Mon, 1 Nov 2021 17:20:00 +0800 | From | Huang Rui <> | Subject | Re: [PATCH v3 05/21] ACPI: CPPC: add cppc enable register function |
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On Fri, Oct 29, 2021 at 10:15:35PM +0800, Limonciello, Mario wrote: > On 10/29/2021 08:02, Huang Rui wrote: > > From: Jinzhou Su <Jinzhou.Su@amd.com> > > > > Add a new function to enable CPPC feature. This function > > will write Continuous Performance Control package > > EnableRegister field on the processor. > > > > CPPC EnableRegister register described in section 8.4.7.1 of ACPI 6.4: > > This element is optional. If supported, contains a resource descriptor > > with a single Register() descriptor that describes a register to which > > OSPM writes a One to enable CPPC on this processor. Before this register > > is set, the processor will be controlled by legacy mechanisms (ACPI > > Pstates, firmware, etc.). > > > > This register will be used for AMD processors to enable amd-pstate > > function instead of legacy ACPI P-States. > > > > Signed-off-by: Jinzhou Su <Jinzhou.Su@amd.com> > > Signed-off-by: Huang Rui <ray.huang@amd.com> > > --- > > drivers/acpi/cppc_acpi.c | 45 ++++++++++++++++++++++++++++++++++++++++ > > include/acpi/cppc_acpi.h | 5 +++++ > > 2 files changed, 50 insertions(+) > > > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > > index c9169c221209..2d2297ef5bf9 100644 > > --- a/drivers/acpi/cppc_acpi.c > > +++ b/drivers/acpi/cppc_acpi.c > > @@ -1275,6 +1275,51 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) > > } > > EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs); > > > > +/** > > + * cppc_set_enable - Set to enable CPPC on the processor by writing the > > + * Continuous Performance Control package EnableRegister feild. > > s/feild/field/ > > > + * @cpu: CPU for which to enable CPPC register. > > + * @enable: 0 - disable, 1 - enable CPPC feature on the processor. > > + * > > + * Return: 0 for success, -ERRNO or -EIO otherwise. > > + */ > > +int cppc_set_enable(int cpu, bool enable) > > +{ > > + int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu); > > + struct cpc_register_resource *enable_reg; > > + struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu); > > + struct cppc_pcc_data *pcc_ss_data = NULL; > > + int ret = -EINVAL; > > + > > + if (!cpc_desc) { > > + pr_debug("No CPC descriptor for CPU:%d\n", cpu); > > + return -EINVAL; > > + } > > Can this actually happen or is just an extra safety check? > Don't you block running based on acpi_cpc_valid? >
It's a helper function in cppc lib, is this possible called on other driver might not be protected by acpi_cpc_valid in future?
Thanks, Ray
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