From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rajendra Nayak Subject: Re: [PATCH 4/8] OMAP2+: PM: idle clkdms only if already in idle Date: Fri, 10 Jun 2011 16:52:18 +0530 Message-ID: <4DF1FE6A.3010202@ti.com> References: <1307616853-28395-1-git-send-email-rnayak@ti.com> <1307616853-28395-2-git-send-email-rnayak@ti.com> <1307616853-28395-3-git-send-email-rnayak@ti.com> <1307616853-28395-4-git-send-email-rnayak@ti.com> <1307616853-28395-5-git-send-email-rnayak@ti.com> <20110610001556.GA9159@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from na3sys009aog111.obsmtp.com ([74.125.149.205]:32870 "EHLO na3sys009aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754621Ab1FJLW2 (ORCPT ); Fri, 10 Jun 2011 07:22:28 -0400 Received: by mail-gx0-f179.google.com with SMTP id 1so2096751gxk.10 for ; Fri, 10 Jun 2011 04:22:27 -0700 (PDT) In-Reply-To: <20110610001556.GA9159@google.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Todd Poynor Cc: linux-omap@vger.kernel.org, paul@pwsan.com, khilman@ti.com, b-cousson@ti.com, santosh.shilimkar@ti.com, linux-arm-kernel@lists.infradead.org On 6/10/2011 5:45 AM, Todd Poynor wrote: >> + int hwsup = 0; >> > >> > if (pwrdm == NULL || IS_ERR(pwrdm)) >> > return -EINVAL; >> > @@ -127,6 +128,7 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u32 state) >> > (pwrdm->flags& PWRDM_HAS_LOWPOWERSTATECHANGE)) { >> > sleep_switch = LOWPOWERSTATE_SWITCH; >> > } else { >> > + hwsup = clkdm_is_idle(pwrdm->pwrdm_clkdms[0]); >> > clkdm_wakeup(pwrdm->pwrdm_clkdms[0]); >> > pwrdm_wait_transition(pwrdm); >> > sleep_switch = FORCEWAKEUP_SWITCH; >> > @@ -142,7 +144,7 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u32 state) >> > >> > switch (sleep_switch) { >> > case FORCEWAKEUP_SWITCH: >> > - if (pwrdm->pwrdm_clkdms[0]->flags& CLKDM_CAN_ENABLE_AUTO) >> > + if (hwsup) >> > clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]); >> > else >> > clkdm_sleep(pwrdm->pwrdm_clkdms[0]); > Is concurrency protection needed here? Not sure if it's expected that > multiple threads would simultaneously manage the state of the same power > domain, or that the associated clock domain would change state > concurrently. Yeah, maybe there is a need for a per-clkdm lock to prevent these concurrency issues. This race between omap_set_pwrdm_state and clk_enable/disable all programming clkdm state was one possibility for a race (even without this series), but with this series to move the clkdm handling into hwmod there are certainly more possibilities (across concurrent omap_hwmod_enable/idle) because the hwmod framework uses per-hwmod lock while the clock framework used a global lock. Thanks for bringing this up. Paul/Benoit any thoughts on if a per-clkdm lock seems reasonable? I just did a quick patch to add per-clkdm locking, it also has a couple instances of arch-specific clkdm calls making calls back to generic clkdm framework fixed, which otherwise would result in recursive locking. ---- From: Rajendra Nayak Date: Fri, 10 Jun 2011 15:42:25 +0530 Subject: [PATCH] OMAP: clockdomain: Add per clkdm lock to prevent concurrent state programming Since the clkdm state programming is now done from within the hwmod framework (which uses a per-hwmod lock) instead of the being done from the clock framework (which used a global lock), there is now a need to have per-clkdm locking to prevent races between different hwmods/modules belonging to the same clock domain concurrently programming the clkdm state. Signed-off-by: Rajendra Nayak --- arch/arm/mach-omap2/clockdomain.c | 42 ++++++++++++++++++++++++++-- arch/arm/mach-omap2/clockdomain.h | 2 + arch/arm/mach-omap2/clockdomain2xxx_3xxx.c | 6 ++- arch/arm/mach-omap2/clockdomain44xx.c | 7 ++-- 4 files changed, 49 insertions(+), 8 deletions(-) diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c index b98a972..374e669 100644 --- a/arch/arm/mach-omap2/clockdomain.c +++ b/arch/arm/mach-omap2/clockdomain.c @@ -92,6 +92,8 @@ static int _clkdm_register(struct clockdomain *clkdm) pwrdm_add_clkdm(pwrdm, clkdm); + spin_lock_init(&clkdm->lock); + pr_debug("clockdomain: registered %s\n", clkdm->name); return 0; @@ -690,6 +692,9 @@ int clkdm_clear_all_sleepdeps(struct clockdomain *clkdm) */ int clkdm_sleep(struct clockdomain *clkdm) { + int ret; + unsigned long flags; + if (!clkdm) return -EINVAL; @@ -704,7 +709,10 @@ int clkdm_sleep(struct clockdomain *clkdm) pr_debug("clockdomain: forcing sleep on %s\n", clkdm->name); - return arch_clkdm->clkdm_sleep(clkdm); + spin_lock_irqsave(&clkdm->lock, flags); + ret = arch_clkdm->clkdm_sleep(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); + return ret; } /** @@ -718,6 +726,9 @@ int clkdm_sleep(struct clockdomain *clkdm) */ int clkdm_wakeup(struct clockdomain *clkdm) { + int ret; + unsigned long flags; + if (!clkdm) return -EINVAL; @@ -732,7 +743,10 @@ int clkdm_wakeup(struct clockdomain *clkdm) pr_debug("clockdomain: forcing wakeup on %s\n", clkdm->name); - return arch_clkdm->clkdm_wakeup(clkdm); + spin_lock_irqsave(&clkdm->lock, flags); + ret = arch_clkdm->clkdm_wakeup(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); + return ret; } /** @@ -747,6 +761,8 @@ int clkdm_wakeup(struct clockdomain *clkdm) */ void clkdm_allow_idle(struct clockdomain *clkdm) { + unsigned long flags; + if (!clkdm) return; @@ -762,8 +778,10 @@ void clkdm_allow_idle(struct clockdomain *clkdm) pr_debug("clockdomain: enabling automatic idle transitions for %s\n", clkdm->name); + spin_lock_irqsave(&clkdm->lock, flags); arch_clkdm->clkdm_allow_idle(clkdm); pwrdm_clkdm_state_switch(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); } /** @@ -777,6 +795,8 @@ void clkdm_allow_idle(struct clockdomain *clkdm) */ void clkdm_deny_idle(struct clockdomain *clkdm) { + unsigned long flags; + if (!clkdm) return; @@ -792,7 +812,9 @@ void clkdm_deny_idle(struct clockdomain *clkdm) pr_debug("clockdomain: disabling automatic idle transitions for %s\n", clkdm->name); + spin_lock_irqsave(&clkdm->lock, flags); arch_clkdm->clkdm_deny_idle(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); } /** @@ -805,6 +827,9 @@ void clkdm_deny_idle(struct clockdomain *clkdm) */ int clkdm_is_idle(struct clockdomain *clkdm) { + int ret; + unsigned long flags; + if (!clkdm) return -EINVAL; @@ -813,7 +838,10 @@ int clkdm_is_idle(struct clockdomain *clkdm) pr_debug("clockdomain: reading idle state for %s\n", clkdm->name); - return arch_clkdm->clkdm_is_idle(clkdm); + spin_lock_irqsave(&clkdm->lock, flags); + ret = arch_clkdm->clkdm_is_idle(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); + return ret; } @@ -835,6 +863,8 @@ int clkdm_is_idle(struct clockdomain *clkdm) */ int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) { + unsigned long flags; + /* * XXX Rewrite this code to maintain a list of enabled * downstream clocks for debugging purposes? @@ -859,9 +889,11 @@ int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) pr_debug("clockdomain: clkdm %s: clk %s now enabled\n", clkdm->name, clk->name); + spin_lock_irqsave(&clkdm->lock, flags); arch_clkdm->clkdm_clk_enable(clkdm); pwrdm_wait_transition(clkdm->pwrdm.ptr); pwrdm_clkdm_state_switch(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); return 0; } @@ -882,6 +914,8 @@ int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) */ int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) { + unsigned long flags; + /* * XXX Rewrite this code to maintain a list of enabled * downstream clocks for debugging purposes? @@ -908,8 +942,10 @@ int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) pr_debug("clockdomain: clkdm %s: clk %s now disabled\n", clkdm->name, clk->name); + spin_lock_irqsave(&clkdm->lock, flags); arch_clkdm->clkdm_clk_disable(clkdm); pwrdm_clkdm_state_switch(clkdm); + spin_unlock_irqrestore(&clkdm->lock, flags); return 0; } diff --git a/arch/arm/mach-omap2/clockdomain.h b/arch/arm/mach-omap2/clockdomain.h index 085ed82..9fd4eb5 100644 --- a/arch/arm/mach-omap2/clockdomain.h +++ b/arch/arm/mach-omap2/clockdomain.h @@ -17,6 +17,7 @@ #define __ARCH_ARM_MACH_OMAP2_CLOCKDOMAIN_H #include +#include #include "powerdomain.h" #include @@ -122,6 +123,7 @@ struct clockdomain { const struct omap_chip_id omap_chip; atomic_t usecount; struct list_head node; + spinlock_t lock; }; /** diff --git a/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c b/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c index e0c393f..f841ac8 100644 --- a/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c +++ b/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c @@ -193,7 +193,8 @@ static int omap2_clkdm_clk_enable(struct clockdomain *clkdm) _clkdm_add_autodeps(clkdm); _enable_hwsup(clkdm); } else { - clkdm_wakeup(clkdm); + if (clkdm->flags & CLKDM_CAN_FORCE_WAKEUP) + omap2_clkdm_wakeup(clkdm); } return 0; @@ -215,7 +216,8 @@ static int omap2_clkdm_clk_disable(struct clockdomain *clkdm) _clkdm_del_autodeps(clkdm); _enable_hwsup(clkdm); } else { - clkdm_sleep(clkdm); + if (clkdm->flags & CLKDM_CAN_FORCE_SLEEP) + omap2_clkdm_sleep(clkdm); } return 0; diff --git a/arch/arm/mach-omap2/clockdomain44xx.c b/arch/arm/mach-omap2/clockdomain44xx.c index e4b8e06..911770b 100644 --- a/arch/arm/mach-omap2/clockdomain44xx.c +++ b/arch/arm/mach-omap2/clockdomain44xx.c @@ -101,7 +101,8 @@ static int omap4_clkdm_is_idle(struct clockdomain *clkdm) static int omap4_clkdm_clk_enable(struct clockdomain *clkdm) { - clkdm_wakeup(clkdm); + if (clkdm->flags & CLKDM_CAN_FORCE_WAKEUP) + return omap4_clkdm_wakeup(clkdm); return 0; } @@ -112,8 +113,8 @@ static int omap4_clkdm_clk_disable(struct clockdomain *clkdm) hwsup = omap4_cminst_is_clkdm_in_hwsup(clkdm->prcm_partition, clkdm->cm_inst, clkdm->clkdm_offs); - if (!hwsup) - clkdm_sleep(clkdm); + if (!hwsup && (clkdm->flags & CLKDM_CAN_FORCE_SLEEP)) + omap4_clkdm_sleep(clkdm); return 0; } -- 1.7.0.4