Linux Power Management development
 help / color / mirror / Atom feed
From: "Gautham R. Shenoy" <gautham.shenoy@amd.com>
To: Mario Limonciello <mario.limonciello@amd.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	K Prateek Nayak <kprateek.nayak@amd.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-pm@vger.kernel.org>,
	"Gautham R. Shenoy" <gautham.shenoy@amd.com>,
	Mario Limonciello <superm1@kernel.org>
Subject: [PATCH v4 02/12] amd-pstate: Update cppc_req_cached in fast_switch case
Date: Thu, 26 Mar 2026 17:17:46 +0530	[thread overview]
Message-ID: <20260326114756.20374-3-gautham.shenoy@amd.com> (raw)
In-Reply-To: <20260326114756.20374-1-gautham.shenoy@amd.com>

The function msr_update_perf() does not cache the new value that is
written to MSR_AMD_CPPC_REQ into the variable cpudata->cppc_req_cached
when the update is happening from the fast path.

Fix that by caching the value everytime the MSR_AMD_CPPC_REQ gets
updated.

This issue was discovered by Claude Opus 4.6 with the aid of Chris
Mason's AI review-prompts
(https://github.com/masoncl/review-prompts/tree/main/kernel).

Assisted-by: Claude:claude-opus-4.6 review-prompts/linux
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Fixes: fff395796917 ("cpufreq/amd-pstate: Always write EPP value when updating perf")
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index d57969c72c9d..24cdeffbcd40 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -261,7 +261,6 @@ static int msr_update_perf(struct cpufreq_policy *policy, u8 min_perf,
 
 	if (fast_switch) {
 		wrmsrq(MSR_AMD_CPPC_REQ, value);
-		return 0;
 	} else {
 		int ret = wrmsrq_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
 
-- 
2.34.1


  parent reply	other threads:[~2026-03-26 11:48 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-26 11:47 [PATCH v4 00/12] amd-pstate: Introduce AMD CPPC Performance Priority Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 01/12] amd-pstate: Fix memory leak in amd_pstate_epp_cpu_init() Gautham R. Shenoy
2026-03-26 11:47 ` Gautham R. Shenoy [this message]
2026-03-26 11:47 ` [PATCH v4 03/12] amd-pstate: Make certain freq_attrs conditionally visible Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 04/12] x86/cpufeatures: Add AMD CPPC Performance Priority feature Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 05/12] amd-pstate: Add support for CPPC_REQ2 and FLOOR_PERF Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 06/12] amd-pstate: Add sysfs support for floor_freq and floor_count Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 07/12] amd-pstate: Introduce a tracepoint trace_amd_pstate_cppc_req2() Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 08/12] amd-pstate-ut: Add module parameter to select testcases Gautham R. Shenoy
2026-03-26 18:46   ` Mario Limonciello
2026-03-26 11:47 ` [PATCH v4 09/12] amd-pstate-ut: Add a testcase to validate the visibility of driver attributes Gautham R. Shenoy
2026-03-26 19:34   ` Mario Limonciello
2026-03-26 11:47 ` [PATCH v4 10/12] Documentation/amd-pstate: List amd_pstate_hw_prefcore sysfs file Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 11/12] Documentation/amd-pstate: List amd_pstate_prefcore_ranking " Gautham R. Shenoy
2026-03-26 11:47 ` [PATCH v4 12/12] Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count} Gautham R. Shenoy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20260326114756.20374-3-gautham.shenoy@amd.com \
    --to=gautham.shenoy@amd.com \
    --cc=kprateek.nayak@amd.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=mario.limonciello@amd.com \
    --cc=rafael@kernel.org \
    --cc=superm1@kernel.org \
    --cc=viresh.kumar@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox