From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Turquette Subject: Re: [PATCH v2] twl4030 reboot workaround Date: Fri, 30 Jul 2010 13:39:20 -0500 Message-ID: <4C531C58.4020803@ti.com> References: <20100729061608.GG12063@edollo> <1280385678-4366-1-git-send-email-ext-mikko.rapeli@nokia.com> <5A47E75E594F054BAF48C5E4FC4B92AB0323D40C6F@dbde02.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:44667 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933327Ab0G3Sj3 (ORCPT ); Fri, 30 Jul 2010 14:39:29 -0400 In-Reply-To: <5A47E75E594F054BAF48C5E4FC4B92AB0323D40C6F@dbde02.ent.ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Gopinath, Thara" Cc: Mike Rapoport , Mikko Rapeli , "linux-omap@vger.kernel.org" , "sameo@linux.intel.com" Gopinath, Thara wrote: > >>> -----Original Message----- >>> From: linux-omap-owner@vger.kernel.org [mailto:linux-omap-owner@vger.kernel.org] On Behalf Of Mike >>> Rapoport >>> Sent: Friday, July 30, 2010 12:41 AM >>> To: Mikko Rapeli >>> Cc: linux-omap@vger.kernel.org; Turquette, Mike; sameo@linux.intel.com >>> Subject: Re: [PATCH v2] twl4030 reboot workaround >>> >>> Hi >>> >>> On Thu, Jul 29, 2010 at 9:41 AM, Mikko Rapeli >>> wrote: >>>> From: Mikko Rapeli >>>> >>>> Original patch: http://marc.info/?l=linux-omap&m=126522625032441&w=2 >>>> >>>> "Removes TWL4030 sleep script prior to rebooting, only on OMAP3. This is >>>> necessary since DPLL3 reset causes SYS_OFFMODE pin to go low, resulting >>>> in the sleep script being executed on TWL4030. This usually results in >>>> VDD1 & VDD2 voltage collapse while ROM code is executing, followed by an >>>> MPU Watch Dog reset or worse, an irrecoverable hang." >>> I had a similar issue when my system hanged on hard reset when there >>> was a TWL sleep script installed. >>> The workaround I've found was to install the sleep script immediately >>> before entering the suspend state and remove the script on the resume >>> path. >>> If you think that such approach is appropriate I can send a patch. > > How do you hit the off state(Vdd's at 0 V) in the idle path then? Or do you do this every > time in the idle thread also? I do not think it is appropriate to add/remove the sleep script before/after every OFF mode case. The script should be programmed once and left alone EXCEPT in the case of warm reset. If there are other corner cases where SYS_OFFMODE goes low, then we should cover those with similar fixes to the warm reset fix, but in general I think the policy should be to leave the scripts alone once programmed Dynamically programming/removing the scripts around OFF transitions increases software overhead for those transitions even more which is very undesirable. Mike > Regards > Thara