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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-851d3362cf8sm2755115b3a.4.2026.08.21.01.54.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 Aug 2026 01:54:08 -0700 (PDT) Message-ID: Date: Fri, 21 Aug 2026 16:54:05 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] cpufreq: acpi-cpufreq: fix P-state index mismatch in get_cur_freq_on_cpu() To: lirongqing , "Rafael J . Wysocki" , Viresh Kumar , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260820020715.2344-1-lirongqing@baidu.com> <20260820020715.2344-3-lirongqing@baidu.com> Content-Language: en-US Cc: zhongqiu.han@oss.qualcomm.com From: Zhongqiu Han In-Reply-To: <20260820020715.2344-3-lirongqing@baidu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODIxMDA2NCBTYWx0ZWRfX2Z3GBhFQvEU9 IaKOTjsHn8dT2CuWfgjbC9i11ee3pE+kIUgK2ku6K28hr+l2q10hLOpDj7hCIJXoUDd5AaIG+0B bMaNRCdt8jyzieQqLw51MAv5Y38ps1Mop8j1jypjms5/6y6hTluLdy4NTAFc+sriGJWFBV6lG5h MZL4FLV5YvECIBlRNRUKLXYBIy05GkqEIa4hadH4wVaPyWHBb8GLeoMckJMmWBGDL8DXVqtsoal h6dIX3X2A1urr8PeyIyaC7LfoZEsx3dHd+9uhjW84jcUVP+1wpzPryXrATAnUBlUmcNOeLQ19d3 uZX0eVfnC+zXjaWgFndXHtxHm2Bv7im5TvCO4M3ERaBGyc/gZwxG/E/uiPyK2aq7BdVwbEA3GjT pPHHW29iXfqJTnWzyNtLBrmBJFOU2F8XQDHo8QLQMvd+K8Nujcwn0Urn3rToLAfH3P+dBRB3a+V g/7Lm4yukqo3+I6heJQ== X-Proofpoint-Spam-Info: AW1haW4tMjYwODIxMDA2NCBTYWx0ZWRfX8NJ3fKeiGAtS L3FkT/6/tXO6Rxq2FVjQDvM+Lo/LLJHQtPa3vDQedowTMDVycd4Fjtd9UmcUc4cFcn8wfa+B5f2 CU+0a0GRW+EE5XFxIwab8te364f23mA= X-Proofpoint-ORIG-GUID: GUjVWTo_zYk0hUOTbdp79WOQaIV4tYnb X-Authority-Analysis: v=2.4 cv=BJyDalQG c=1 sm=1 tr=0 ts=6a881232 cx=c_pps a=m5Vt/hrsBiPMCU0y4gIsQw==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=zuLzuavZAAAA:8 a=EUspDBNiAAAA:8 a=X-4reRNKfApO1qCbSG0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=IoOABgeZipijB_acs4fv:22 X-Proofpoint-GUID: GUjVWTo_zYk0hUOTbdp79WOQaIV4tYnb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-21_02,2026-08-21_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 bulkscore=0 clxscore=1015 impostorscore=0 adultscore=0 phishscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608210064 On 8/20/2026 10:07 AM, lirongqing wrote: > From: Li RongQing > > get_cur_freq_on_cpu() uses perf->state, which is an index into > perf->states[], to index policy->freq_table[]. However, freq_table[] > is built by filtering _PSS entries with duplicate frequencies, so its To be precise for applying if needed. "However, freq_table[] is built by filtering _PSS entries with duplicate frequencies" --> "However, freq_table[] is built by filtering _PSS entries that are not lower in frequency than the previous one." > index space no longer matches perf->states[]. The original P-state > index for each remaining freq_table entry is stored in driver_data. > > Once an entry has been skipped, using perf->state as an index into > freq_table[] can therefore select the frequency of a different > P-state. > > The reported current frequency itself remains correct because it is > obtained from extract_freq(). The mismatch only affects the cached > frequency used by get_cur_freq_on_cpu() to detect a firmware frequency > change behind our back, through data->resume. Just for applying if needed， deleting "through data->resume." > > If the wrong table entry contains a frequency different from the one > the CPU is actually running at, the check falsely detects a frequency > change and sets data->resume. The next ->target() call then performs a > redundant control-register write even if the requested P-state is > already the current P-state. > > Conversely, if the wrong table entry happens to contain the frequency > to which firmware has changed the CPU, the frequency change is missed > and data->resume remains clear. A subsequent ->target() call for the > P-state that the cpufreq core believes to be current can then > short-circuit without rewriting the control register, leaving the CPU > at the firmware-selected frequency until a different P-state is > requested. > > Fix this by taking the cached frequency directly from > perf->states[perf->state].core_frequency. perf->state and > perf->states[] use the same P-state index space, and converting > core_frequency to kHz yields the same value stored in the corresponding > freq_table entry during initialization. > > Fixes: e56a727b023d ("[CPUFREQ] Make acpi-cpufreq more robust against BIOS freq changes behind our back.") > Reported-by: Zhongqiu Han > Suggested-by: Zhongqiu Han > Signed-off-by: Li RongQing Reviewed-by: Zhongqiu Han > --- > drivers/cpufreq/acpi-cpufreq.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c > index a797bb2..3313c74 100644 > --- a/drivers/cpufreq/acpi-cpufreq.c > +++ b/drivers/cpufreq/acpi-cpufreq.c > @@ -353,6 +353,7 @@ static u32 get_cur_val(const struct cpumask *mask, struct acpi_cpufreq_data *dat > > static unsigned int get_cur_freq_on_cpu(unsigned int cpu) > { > + struct acpi_processor_performance *perf; > struct acpi_cpufreq_data *data; > struct cpufreq_policy *policy; > unsigned int freq; > @@ -368,7 +369,9 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu) > if (unlikely(!data || !policy->freq_table)) > return 0; > > - cached_freq = policy->freq_table[to_perf_data(data)->state].frequency; > + perf = to_perf_data(data); > + cached_freq = perf->states[perf->state].core_frequency * 1000; > + > freq = extract_freq(policy, get_cur_val(cpumask_of(cpu), data)); > if (freq != cached_freq) { > /* -- Thx and BRs, Zhongqiu Han