lkml.org 
[lkml]   [2021]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 05/21] ACPI: CPPC: add cppc enable register function
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

\
 
 \ /
  Last update: 2021-11-01 10:23    [W:0.197 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site