Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752233AbcKGHj3 (ORCPT ); Mon, 7 Nov 2016 02:39:29 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:36286 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbcKGHj1 (ORCPT ); Mon, 7 Nov 2016 02:39:27 -0500 From: Akshay Adiga To: rjw@rjwysocki.net, ego@linux.vnet.ibm.com, shilpa.bhat@linux.vnet.ibm.com, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Akshay Adiga Subject: [PATCH v2 2/2] cpufreq: powernv: Use PMCR to verify global and local pstate Date: Mon, 7 Nov 2016 13:09:09 +0530 X-Mailer: git-send-email 2.5.5 In-Reply-To: <1478504349-14796-1-git-send-email-akshay.adiga@linux.vnet.ibm.com> References: <1478504349-14796-1-git-send-email-akshay.adiga@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16110707-0052-0000-0000-000001E4B5DE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16110707-0053-0000-0000-00000725CE29 Message-Id: <1478504349-14796-2-git-send-email-akshay.adiga@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-07_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-1611070145 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3889 Lines: 105 As fast_switch() may get called with interrupt disable mode, we cannot hold a mutex to update the global_pstate_info. So currently, fast_switch() does not update the global_pstate_info and it will end up with stale data whenever pstate is updated through fast_switch(). As the gpstate_timer can fire after fast_switch() has updated the pstates, the timer handler cannot rely on the cached values of local and global pstate and needs to read it from the PMCR. Only gpstate_timer_handler() is affected by the stale cached pstate data beacause either fast_switch() or target_index() routines will be called for a given govenor, but gpstate_timer can fire after the governor has changed to schedutil. Signed-off-by: Akshay Adiga --- Changes from v1 : - Corrected Commit message - Type cast pstate values read from PMCR to type s8 - Added Macros to get local and global pstates from PMCR drivers/cpufreq/powernv-cpufreq.c | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c index 4a4380d..bf4bc585 100644 --- a/drivers/cpufreq/powernv-cpufreq.c +++ b/drivers/cpufreq/powernv-cpufreq.c @@ -42,6 +42,8 @@ #define PMSR_PSAFE_ENABLE (1UL << 30) #define PMSR_SPR_EM_DISABLE (1UL << 31) #define PMSR_MAX(x) ((x >> 32) & 0xFF) +#define PMCR_LPSTATE(x) (((x) >> 48) & 0xFF) +#define PMCR_GPSTATE(x) (((x) >> 56) & 0xFF) #define MAX_RAMP_DOWN_TIME 5120 /* @@ -592,7 +594,8 @@ 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 +603,36 @@ 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 = (s8)PMCR_GPSTATE(val); + freq_data.pstate_id = (s8)PMCR_LPSTATE(val); + 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 +640,6 @@ 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 */ -- 2.5.5