Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753190AbbKJN6U (ORCPT ); Tue, 10 Nov 2015 08:58:20 -0500 Received: from mail-wm0-f44.google.com ([74.125.82.44]:33772 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752484AbbKJN6S (ORCPT ); Tue, 10 Nov 2015 08:58:18 -0500 Message-ID: <5641F7F5.2040901@baylibre.com> Date: Tue, 10 Nov 2015 14:58:13 +0100 From: Axel Haslam User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Zhaoyang Huang CC: Kevin Hilman , Ulf Hansson , Lina Iyer , geert@glider.be, k.kozlowski.k@gmail.com, rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, bcousson@baylibre.com, mturquette@baylibre.com, Axel Haslam Subject: Re: [PATCH v10 3/6] PM / Domains: make governor select deepest state References: <1445347589-5626-1-git-send-email-ahaslam@baylibre.com> <1445347589-5626-4-git-send-email-ahaslam@baylibre.com> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3828 Lines: 99 Hi Zhaoyang, >> @@ -209,14 +186,52 @@ static bool default_power_down_ok(struct dev_pm_domain *pd) >> * The difference between the computed minimum subdomain or device off >> * time and the time needed to turn the domain on is the maximum >> * theoretical time this domain can spend in the "off" state. >> - * Use the only available state, until multiple state support is added >> - * to the governor. >> */ >> genpd->max_off_time_ns = min_off_time_ns - >> - genpd->states[0].power_on_latency_ns; >> + genpd->states[state].power_on_latency_ns; >> return true; >> } > [question]: Does it mean that the sleep level is just decided by > comparing the pre-configure on_off time with the gpd_timing_data? How > about the next timer event which affect the sleep depth on cpuidle > framework? There are a couple of patches on the list ill try to summarize what i understand, Lina, Marc please correct me if im wrong! I did this patches thinking generally about devices in a power domain and not so much about a cpu. So these patches are not aimed at replacing cpuidle, but were meant for power domains that may have intermediate states, for example some logic may be implemented with retention flip-flops. There is the proposal by Lina [1] to add cpus clusters to powerdomins and by Marc[2] that tie cluster idle states to the powerdomain handler. but i think the effort here is to complement cpuidle rather than to replace it. regards Axel 1. https://lwn.net/Articles/653579/ 2. https://lwn.net/Articles/658461/ >> >> +static bool default_power_down_ok(struct dev_pm_domain *pd) >> +{ >> + struct generic_pm_domain *genpd = pd_to_genpd(pd); >> + unsigned int last_state_idx = genpd->state_count - 1; >> + struct gpd_link *link; >> + bool retval = false; >> + unsigned int i; >> + >> + /* >> + * if there was no change on max_off_time, we can return the >> + * cached value and we dont need to find a new target_state >> + */ >> + if (!genpd->max_off_time_changed) >> + return genpd->cached_power_down_ok; >> + >> + /* >> + * We have to invalidate the cached results for the masters, so >> + * use the observation that default_power_down_ok() is not >> + * going to be called for any master until this instance >> + * returns. >> + */ >> + list_for_each_entry(link, &genpd->slave_links, slave_node) >> + link->master->max_off_time_changed = true; >> + >> + genpd->max_off_time_ns = -1; >> + genpd->max_off_time_changed = false; >> + >> + /* find a state to power down to, starting from the deepest */ >> + for (i = 0; i < genpd->state_count; i++) { >> + if (power_down_ok_for_state(pd, last_state_idx - i)) { >> + genpd->state_idx = last_state_idx - i; >> + retval = true; >> + break; >> + } >> + } >> + >> + genpd->cached_power_down_ok = retval; >> + return retval; >> +} >> + >> static bool always_on_power_down_ok(struct dev_pm_domain *domain) >> { >> return false; > [question]How the TICK_NOHZ treated if we substitute cpuidle framework > with this one? >> -- >> 2.4.5 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-pm" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/