From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E65F1C433ED for ; Wed, 14 Apr 2021 17:46:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B453161090 for ; Wed, 14 Apr 2021 17:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233851AbhDNRqz (ORCPT ); Wed, 14 Apr 2021 13:46:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231582AbhDNRqz (ORCPT ); Wed, 14 Apr 2021 13:46:55 -0400 Received: from mail-yb1-xb30.google.com (mail-yb1-xb30.google.com [IPv6:2607:f8b0:4864:20::b30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97C12C061574 for ; Wed, 14 Apr 2021 10:46:33 -0700 (PDT) Received: by mail-yb1-xb30.google.com with SMTP id v72so2341822ybe.11 for ; Wed, 14 Apr 2021 10:46:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ac8RD2WukXjSqpfh7k38X0swu0LeGtgNE/nGq1NqhZk=; b=Mpmo8WUQ7E9nwFU9kE7K21n5vUwZQIupntBULLtSMZazk5A4w5pTT8kVn7wFReuqP9 ltqs6kRlZv8yf+IjJ8qiV3rGvqAB2jej7ERMJieNnVuEH+1SGE8mdNtB1hyN/nhCwR5c CzmfEcHkI2vHfjSc1u1cE9UejF5L8aHuNIkFS8k7KWzDwQCaOuDxgFn/N91weuCeh0TF EJMxkouixLYBcBce5jqfzW1fzoEnBPNBw8ST/jEanDbqYvkcTO8yHHRr7fTSUT0Wpncj RUhjF5+un/cBrectZkWI296fpy0ehcH3tVZu2d0vGznFuZ26eK0IU84SrP8nBPsh0fJ+ 56yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ac8RD2WukXjSqpfh7k38X0swu0LeGtgNE/nGq1NqhZk=; b=pCDfjSt68eNtjIsDyD1N+i9t4wMMEZ8rAwSk3yo7di1STjkYi3Z1zU3z1qaks1APDN xkFMszjYdCMkv71PnUagWO7EUXSG3ngwqXK+fOjSS8BLCcUIGvd2eWEnTc6Tk1QAYs2b Cyd2biB00tCPnSZDiurOqfp3mdx2eqLtpSrBzT4DMU75y3/MWePbRHuOmcbBk56+YCmk GZKEeIzbDrsIcU2NFLJSqscMi4Lqpq/3oR/5YB5lGXd/al2HqwnPGjtLeOITpTZzq0j3 97tfnaLLROfoD4wBLPGtnvlzj5cGhGNslpX16gjM+95b8xaIiu/jua6OwtUKsWKuTa+g MlGg== X-Gm-Message-State: AOAM532hMCjQC9aepoml/nr79wslbvO1h2I7myvCQ93To2yoyiZ7TKCb +77J2N52PmzYRdiyBjgsQr3+nW9nzUrna1ba7FVnyA== X-Google-Smtp-Source: ABdhPJz0pPK+rUAhIDOL4XNp3AJeh80jyTHZqv7aLfz61blbu6YkHLnA5fHXMyxERM1pxxugJoMb3tWUaGRARXf3KfI= X-Received: by 2002:a25:c985:: with SMTP id z127mr57011363ybf.20.1618422392561; Wed, 14 Apr 2021 10:46:32 -0700 (PDT) MIME-Version: 1.0 References: <20210407034456.516204-1-saravanak@google.com> <20210407034456.516204-3-saravanak@google.com> In-Reply-To: <20210407034456.516204-3-saravanak@google.com> From: Saravana Kannan Date: Wed, 14 Apr 2021 10:45:56 -0700 Message-ID: Subject: Re: [PATCH v1 2/2] clk: Add support for sync_state() To: Saravana Kannan Cc: Greg Kroah-Hartman , Michael Turquette , Stephen Boyd , Android Kernel Team , linux-clk , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 6, 2021 at 8:45 PM 'Saravana Kannan' via kernel-team wrote: > > Clocks can be turned on (by the hardware, bootloader, etc) upon a > reset/boot of a hardware platform. These "boot clocks" could be clocking > devices that are active before the kernel starts running. For example, > clocks needed for the interconnects, UART console, display, CPUs, DDR, > etc. > > When a boot clock is used by more than one consumer or multiple boot > clocks share a parent clock, the boot clock (or the common parent) can > be turned off when the first consumer probes. This can crash the device > or cause poor user experience. > > Fix this by explicitly enabling the boot clocks during clock > registration and then removing the enable vote when the clock provider > device gets its sync_state() callback. Since sync_state() callback comes > only when all the consumers of a device (not a specific clock) have > probed, this ensures the boot clocks are kept on at least until all > their consumers have had a chance to vote on them (in their respective > probe functions). > > Also, if a clock provider is loaded as a module and it has some boot > clocks, they get turned off only when a consumer explicitly turns them > off. So clocks that are boot clocks and are unused never get turned off > because the logic to turn off unused clocks has already run during > late_initcall_sync(). Adding sync_state() support also makes sure these > unused boot clocks are turned off once all the consumers have probed. > > Signed-off-by: Saravana Kannan Hi Stephen, Gentle reminder. -Saravana > --- > drivers/clk/clk.c | 84 +++++++++++++++++++++++++++++++++++- > include/linux/clk-provider.h | 1 + > 2 files changed, 84 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index d6301a3351f2..cd07f4d1254c 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -72,6 +72,8 @@ struct clk_core { > unsigned long flags; > bool orphan; > bool rpm_enabled; > + bool need_sync; > + bool boot_enabled; > unsigned int enable_count; > unsigned int prepare_count; > unsigned int protect_count; > @@ -1215,6 +1217,15 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core) > hlist_for_each_entry(child, &core->children, child_node) > clk_unprepare_unused_subtree(child); > > + /* > + * Orphan clocks might still not have their state held if one of their > + * ancestors hasn't been registered yet. We don't want to turn off > + * these orphan clocks now as they will be turned off later when their > + * device gets a sync_state() call. > + */ > + if (dev_has_sync_state(core->dev)) > + return; > + > if (core->prepare_count) > return; > > @@ -1246,6 +1257,15 @@ static void __init clk_disable_unused_subtree(struct clk_core *core) > hlist_for_each_entry(child, &core->children, child_node) > clk_disable_unused_subtree(child); > > + /* > + * Orphan clocks might still not have their state held if one of their > + * ancestors hasn't been registered yet. We don't want to turn off > + * these orphan clocks now as they will be turned off later when their > + * device gets a sync_state() call. > + */ > + if (dev_has_sync_state(core->dev)) > + return; > + > if (core->flags & CLK_OPS_PARENT_ENABLE) > clk_core_prepare_enable(core->parent); > > @@ -1319,6 +1339,38 @@ static int __init clk_disable_unused(void) > } > late_initcall_sync(clk_disable_unused); > > +static void clk_unprepare_disable_dev_subtree(struct clk_core *core, > + struct device *dev) > +{ > + struct clk_core *child; > + > + lockdep_assert_held(&prepare_lock); > + > + hlist_for_each_entry(child, &core->children, child_node) > + clk_unprepare_disable_dev_subtree(child, dev); > + > + if (core->dev != dev || !core->need_sync) > + return; > + > + clk_core_disable_unprepare(core); > +} > + > +void clk_sync_state(struct device *dev) > +{ > + struct clk_core *core; > + > + clk_prepare_lock(); > + > + hlist_for_each_entry(core, &clk_root_list, child_node) > + clk_unprepare_disable_dev_subtree(core, dev); > + > + hlist_for_each_entry(core, &clk_orphan_list, child_node) > + clk_unprepare_disable_dev_subtree(core, dev); > + > + clk_prepare_unlock(); > +} > +EXPORT_SYMBOL_GPL(clk_sync_state); > + > static int clk_core_determine_round_nolock(struct clk_core *core, > struct clk_rate_request *req) > { > @@ -1725,6 +1777,30 @@ int clk_hw_get_parent_index(struct clk_hw *hw) > } > EXPORT_SYMBOL_GPL(clk_hw_get_parent_index); > > +static void clk_core_hold_state(struct clk_core *core) > +{ > + if (core->need_sync || !core->boot_enabled) > + return; > + > + if (core->orphan || !dev_has_sync_state(core->dev)) > + return; > + > + core->need_sync = !clk_core_prepare_enable(core); > +} > + > +static void __clk_core_update_orphan_hold_state(struct clk_core *core) > +{ > + struct clk_core *child; > + > + if (core->orphan) > + return; > + > + clk_core_hold_state(core); > + > + hlist_for_each_entry(child, &core->children, child_node) > + __clk_core_update_orphan_hold_state(child); > +} > + > /* > * Update the orphan status of @core and all its children. > */ > @@ -3392,6 +3468,7 @@ static void clk_core_reparent_orphans_nolock(void) > __clk_set_parent_after(orphan, parent, NULL); > __clk_recalc_accuracies(orphan); > __clk_recalc_rates(orphan, 0); > + __clk_core_update_orphan_hold_state(orphan); > } > } > } > @@ -3550,6 +3627,8 @@ static int __clk_core_init(struct clk_core *core) > rate = 0; > core->rate = core->req_rate = rate; > > + core->boot_enabled = clk_core_is_enabled(core); > + > /* > * Enable CLK_IS_CRITICAL clocks so newly added critical clocks > * don't get accidentally disabled when walking the orphan tree and > @@ -3572,6 +3651,7 @@ static int __clk_core_init(struct clk_core *core) > } > } > > + clk_core_hold_state(core); > clk_core_reparent_orphans_nolock(); > > > @@ -3837,8 +3917,10 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw) > core->rpm_enabled = true; > core->dev = dev; > core->of_node = np; > - if (dev && dev->driver) > + if (dev && dev->driver) { > core->owner = dev->driver->owner; > + dev_set_drv_sync_state(dev, clk_sync_state); > + } > core->hw = hw; > core->flags = init->flags; > core->num_parents = init->num_parents; > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > index 58f6fe866ae9..429c413dadce 100644 > --- a/include/linux/clk-provider.h > +++ b/include/linux/clk-provider.h > @@ -1112,6 +1112,7 @@ void devm_clk_unregister(struct device *dev, struct clk *clk); > > void clk_hw_unregister(struct clk_hw *hw); > void devm_clk_hw_unregister(struct device *dev, struct clk_hw *hw); > +void clk_sync_state(struct device *dev); > > /* helper functions */ > const char *__clk_get_name(const struct clk *clk); > -- > 2.31.1.295.g9ea45b61b8-goog > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >