From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: rjw@rjwysocki.net, lenb@kernel.org, viresh.kumar@linaro.org
Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org, pprakash@codeaurora.org,
wangxiongfeng2@huawei.com, srinivas.pandruvada@linux.intel.com
Subject: [PATCH v2 1/2] ACPI / CPPC: Fix processing for guaranteed performance
Date: Mon, 25 Mar 2019 09:04:39 -0700 [thread overview]
Message-ID: <20190325160440.7575-2-srinivas.pandruvada@linux.intel.com> (raw)
In-Reply-To: <20190325160440.7575-1-srinivas.pandruvada@linux.intel.com>
As per ACPI specification "Guaranteed Performance Register" is a "Buffer"
field. It can't be "Integer" field. So treat "Integer" type as invalid and
ignore "Guaranteed Performance Register".
Also save one cpc_read() call, when "Guaranteed Performance Register" is
not present, which means register defined as:
"Register(SystemMemory, 0, 0, 0, 0)".
Fixes: 29523f095397 ("ACPI / CPPC: Add support for guaranteed performance")
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 4.20+ <stable@vger.kernel.org> # 4.20+
---
drivers/acpi/cppc_acpi.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 1b207fca1420..d4244e7d0e38 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1150,8 +1150,13 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
cpc_read(cpunum, nominal_reg, &nom);
perf_caps->nominal_perf = nom;
- cpc_read(cpunum, guaranteed_reg, &guaranteed);
- perf_caps->guaranteed_perf = guaranteed;
+ if (guaranteed_reg->type != ACPI_TYPE_BUFFER ||
+ IS_NULL_REG(&guaranteed_reg->cpc_entry.reg)) {
+ perf_caps->guaranteed_perf = 0;
+ } else {
+ cpc_read(cpunum, guaranteed_reg, &guaranteed);
+ perf_caps->guaranteed_perf = guaranteed;
+ }
cpc_read(cpunum, lowest_non_linear_reg, &min_nonlinear);
perf_caps->lowest_nonlinear_perf = min_nonlinear;
--
2.17.2
next prev parent reply other threads:[~2019-03-25 16:04 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 16:04 [PATCH v2 0/2] Correct the processing for base_frequency Srinivas Pandruvada
2019-03-25 16:04 ` Srinivas Pandruvada [this message]
2019-03-25 16:04 ` [PATCH v2 2/2] cpufreq: intel_pstate: Also use cppc nominal_perf " Srinivas Pandruvada
2019-03-26 11:38 ` [PATCH v2 0/2] Correct the processing " Rafael J. Wysocki
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