From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH v2 09/18] ARM: OMAP4+: PM: Restore CPU power state to ON with clockdomain force wakeup method Date: Fri, 5 Apr 2013 14:37:01 +0530 Message-ID: <515E9435.6050007@ti.com> References: <1364205910-32392-1-git-send-email-santosh.shilimkar@ti.com> <1364205910-32392-10-git-send-email-santosh.shilimkar@ti.com> <87mwtftjvy.fsf@linaro.org> <515D8215.10705@ti.com> <87li8ynqf5.fsf@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from bear.ext.ti.com ([192.94.94.41]:55043 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751136Ab3DEJFE (ORCPT ); Fri, 5 Apr 2013 05:05:04 -0400 In-Reply-To: <87li8ynqf5.fsf@linaro.org> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Kevin Hilman Cc: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, nm@ti.com, tony@atomide.com On Thursday 04 April 2013 11:12 PM, Kevin Hilman wrote: > Santosh Shilimkar writes: > >> On Thursday 04 April 2013 02:24 AM, Kevin Hilman wrote: >>> Santosh Shilimkar writes: >>> >>>> While waking up CPU from off state using clock domain force wakeup, restore >>>> the CPU power state to ON state before putting CPU clock domain under >>>> hardware control. Otherwise CPU wakeup might fail. The change is recommended >>>> for all OMAP4+ devices though the PRCM weakness was observed on OMAP5 >>>> devices first. >>> >>> Sounds reasonable, but can you describe the "weakness" a little more? >>> >>> IOW, what exactly happens if this is not done? It sounds like the CPU >>> might immediately go back to retention, but how does that happen unless >>> it does a WFI? >>> >> Its more of lock-up inside the hardware state machine and results >> are UN-predictable. We have seen hard-locks most of the time where system >> is just frozen. The hardware gets into wrong state machine if the power >> domain state isn't restored. I will add this information to changelog. >> >>> Also, this sounds like a fix to me, and should probably be broken out >>> accordingly. >>> >> Yeah. You mean a separate patch from the series, right ? This patch >> actually can be independently added. >> >> In case you decide to apply it for the fixes branch, updated patch >> at end of the email. > > Curious which branch you applied it to? It didn't apply cleanly to > v3.9-rc5 (but did with fuzz). > Mostly applied on top of the Tony's pull request branches. > So I've now added it to my for_3.10/fixes/pm branch. > Thanks. I will pull that in to re-base other patches. Regards, Santosh From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@ti.com (Santosh Shilimkar) Date: Fri, 5 Apr 2013 14:37:01 +0530 Subject: [PATCH v2 09/18] ARM: OMAP4+: PM: Restore CPU power state to ON with clockdomain force wakeup method In-Reply-To: <87li8ynqf5.fsf@linaro.org> References: <1364205910-32392-1-git-send-email-santosh.shilimkar@ti.com> <1364205910-32392-10-git-send-email-santosh.shilimkar@ti.com> <87mwtftjvy.fsf@linaro.org> <515D8215.10705@ti.com> <87li8ynqf5.fsf@linaro.org> Message-ID: <515E9435.6050007@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 04 April 2013 11:12 PM, Kevin Hilman wrote: > Santosh Shilimkar writes: > >> On Thursday 04 April 2013 02:24 AM, Kevin Hilman wrote: >>> Santosh Shilimkar writes: >>> >>>> While waking up CPU from off state using clock domain force wakeup, restore >>>> the CPU power state to ON state before putting CPU clock domain under >>>> hardware control. Otherwise CPU wakeup might fail. The change is recommended >>>> for all OMAP4+ devices though the PRCM weakness was observed on OMAP5 >>>> devices first. >>> >>> Sounds reasonable, but can you describe the "weakness" a little more? >>> >>> IOW, what exactly happens if this is not done? It sounds like the CPU >>> might immediately go back to retention, but how does that happen unless >>> it does a WFI? >>> >> Its more of lock-up inside the hardware state machine and results >> are UN-predictable. We have seen hard-locks most of the time where system >> is just frozen. The hardware gets into wrong state machine if the power >> domain state isn't restored. I will add this information to changelog. >> >>> Also, this sounds like a fix to me, and should probably be broken out >>> accordingly. >>> >> Yeah. You mean a separate patch from the series, right ? This patch >> actually can be independently added. >> >> In case you decide to apply it for the fixes branch, updated patch >> at end of the email. > > Curious which branch you applied it to? It didn't apply cleanly to > v3.9-rc5 (but did with fuzz). > Mostly applied on top of the Tony's pull request branches. > So I've now added it to my for_3.10/fixes/pm branch. > Thanks. I will pull that in to re-base other patches. Regards, Santosh