Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933866AbcKDF1x (ORCPT ); Fri, 4 Nov 2016 01:27:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41633 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933389AbcKDF1u (ORCPT ); Fri, 4 Nov 2016 01:27:50 -0400 From: Akshay Adiga To: rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Akshay Adiga Subject: [PATCH 2/2] cpufreq: powernv: Use PMSR to verify global and local pstate Date: Fri, 4 Nov 2016 10:57:35 +0530 X-Mailer: git-send-email 2.5.5 In-Reply-To: <1478237255-4258-1-git-send-email-akshay.adiga@linux.vnet.ibm.com> References: <1478237255-4258-1-git-send-email-akshay.adiga@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16110405-0048-0000-0000-000001D22858 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16110405-0049-0000-0000-000046E16ABA Message-Id: <1478237255-4258-2-git-send-email-akshay.adiga@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-04_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1611040102 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3186 Lines: 84 As fast_switch may get called in interrupt disable mode, it does not update the global_pstate_info data structure. Hence the global_pstate_info has stale data whenever pstate is updated through fast_swtich(). So the gpstate_timer can fire after a fast_switch() call has update the pstates to a different value. Hence the timer handler cannot rely on the cached values of local and global pstate and needs to read it from the PMSR. Signed-off-by: Akshay Adiga --- drivers/cpufreq/powernv-cpufreq.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index 09a0496..57713b5 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -592,7 +592,8 @@ void gpstate_timer_handler(unsigned long data) { struct cpufreq_policy *policy = (struct cpufreq_policy *)data; struct global_pstate_info *gpstates = policy->driver_data; - int gpstate_idx; + int gpstate_idx, lpstate_idx; + unsigned long val; unsigned int time_diff = jiffies_to_msecs(jiffies) - gpstates->last_sampled_time; struct powernv_smp_call_data freq_data; @@ -600,21 +601,36 @@ void gpstate_timer_handler(unsigned long data) if (!spin_trylock(&gpstates->gpstate_lock)) return; + /* + * If PMCR was last updated was using fast_swtich then + * We may have wrong in gpstate->last_lpstate_idx + * value. Hence, read from PMCR to get correct data. + */ + val = get_pmspr(SPRN_PMCR); + freq_data.gpstate_id = (val >> (56)) & 0xFF; + freq_data.pstate_id = (val >> (48)) & 0xFF; + if (freq_data.gpstate_id == freq_data.pstate_id) { + reset_gpstates(policy); + spin_unlock(&gpstates->gpstate_lock); + return; + } + gpstates->last_sampled_time += time_diff; gpstates->elapsed_time += time_diff; - freq_data.pstate_id = idx_to_pstate(gpstates->last_lpstate_idx); - if ((gpstates->last_gpstate_idx == gpstates->last_lpstate_idx) || - (gpstates->elapsed_time > MAX_RAMP_DOWN_TIME)) { + if (gpstates->elapsed_time > MAX_RAMP_DOWN_TIME) { gpstate_idx = pstate_to_idx(freq_data.pstate_id); reset_gpstates(policy); gpstates->highest_lpstate_idx = gpstate_idx; } else { + lpstate_idx = pstate_to_idx(freq_data.pstate_id); gpstate_idx = calc_global_pstate(gpstates->elapsed_time, gpstates->highest_lpstate_idx, - gpstates->last_lpstate_idx); + lpstate_idx); } - + freq_data.gpstate_id = idx_to_pstate(gpstate_idx); + gpstates->last_gpstate_idx = gpstate_idx; + gpstates->last_lpstate_idx = lpstate_idx; /* * If local pstate is equal to global pstate, rampdown is over * So timer is not required to be queued. @@ -622,10 +638,6 @@ void gpstate_timer_handler(unsigned long data) if (gpstate_idx != gpstates->last_lpstate_idx) queue_gpstate_timer(gpstates); - freq_data.gpstate_id = idx_to_pstate(gpstate_idx); - gpstates->last_gpstate_idx = pstate_to_idx(freq_data.gpstate_id); - gpstates->last_lpstate_idx = pstate_to_idx(freq_data.pstate_id); - spin_unlock(&gpstates->gpstate_lock); /* Timer may get migrated to a different cpu on cpu hot unplug */ -- 2.7.4