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From:   Perry Yuan <Perry.Yuan@amd.com>
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        <linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Perry Yuan <Perry.Yuan@amd.com>
Subject: [PATCH v2 4/5] Documentation: amd-pstate: add driver working mode introduction
Date:   Thu, 17 Nov 2022 15:19:09 +0800
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Introduce the `amd_pstate` driver new working mode with
`amd_pstate=3Dpassive` added to kernel command line.
If there is no passive mode enabled by user, amd_pstate driver will be
disabled by default for now.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: Wyes Karny <wyes.karny@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
 Documentation/admin-guide/pm/amd-pstate.rst | 30 +++++++++------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/ad=
min-guide/pm/amd-pstate.rst
index 8f3d30c5a0d8..06e23538f79c 100644
--- a/Documentation/admin-guide/pm/amd-pstate.rst
+++ b/Documentation/admin-guide/pm/amd-pstate.rst
@@ -283,23 +283,19 @@ efficiency frequency management method on AMD process=
ors.
 Kernel Module Options for ``amd-pstate``
 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=20
-.. _shared_mem:
-
-``shared_mem``
-Use a module param (shared_mem) to enable related processors manually with
-**amd_pstate.shared_mem=3D1**.
-Due to the performance issue on the processors with `Shared Memory Support
-<perf_cap_>`_, we disable it presently and will re-enable this by default
-once we address performance issue with this solution.
-
-To check whether the current processor is using `Full MSR Support <perf_ca=
p_>`_
-or `Shared Memory Support <perf_cap_>`_ : ::
-
-  ray@hr-test1:~$ lscpu | grep cppc
-  Flags:                           fpu vme de pse tsc msr pae mce cx8 apic=
 sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mm=
xext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpui=
d extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 s=
se4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm =
extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt =
tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp=
_l3 hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2=
 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsa=
vec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero=
 irperf xsaveerptr rdpru wbnoinvd cppc arat npt lbrv svm_lock nrip_save tsc=
_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_=
vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid overflo=
w_recov succor smca fsrm
-
-If the CPU flags have ``cppc``, then this processor supports `Full MSR Sup=
port
-<perf_cap_>`_. Otherwise, it supports `Shared Memory Support <perf_cap_>`_.
+Passive Mode
+------------
+
+``amd_pstate=3Dpassive``
+
+It will be enabled if the ``amd_pstate=3Dpassive`` is passed to the kernel=
 in the command line.
+In this mode, ``amd_pstate`` driver software specifies a desired QoS targe=
t in the CPPC
+performance scale as a relative number. This can be expressed as percentag=
e of nominal
+performance (infrastructure max). Below the nominal sustained performance =
level,
+desired performance expresses the average performance level of the process=
or subject
+to the Performance Reduction Tolerance register. Above the nominal perform=
ance level,
+processor must provide at least nominal performance requested and go highe=
r if current
+operating conditions allow.
=20
=20
 ``cpupower`` tool support for ``amd-pstate``
--=20
2.25.1