From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: Re: [PATCH v2] twl4030 reboot workaround Date: Sun, 01 Aug 2010 09:31:55 +0300 Message-ID: <4C5514DB.9020508@compulab.co.il> References: <20100729061608.GG12063@edollo> <1280385678-4366-1-git-send-email-ext-mikko.rapeli@nokia.com> <5A47E75E594F054BAF48C5E4FC4B92AB0323D40C6F@dbde02.ent.ti.com> <4C531C58.4020803@ti.com> <5A47E75E594F054BAF48C5E4FC4B92AB0323D40F1B@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 compulab.co.il ([67.18.134.219]:41535 "EHLO compulab.co.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751368Ab0HAGcs (ORCPT ); Sun, 1 Aug 2010 02:32:48 -0400 In-Reply-To: <5A47E75E594F054BAF48C5E4FC4B92AB0323D40F1B@dbde02.ent.ti.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Gopinath, Thara" Cc: "Turquette, Mike" , Mikko Rapeli , "linux-omap@vger.kernel.org" , "sameo@linux.intel.com" , Mike Rapoport Gopinath, Thara wrote: > >>> -----Original Message----- >>> From: Turquette, Mike >>> Sent: Saturday, July 31, 2010 12:09 AM >>> To: Gopinath, Thara >>> Cc: Mike Rapoport; Mikko Rapeli; linux-omap@vger.kernel.org; sameo@linux.intel.com >>> Subject: Re: [PATCH v2] twl4030 reboot workaround >>> >>> 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. > > This was exactly my concern. The latency increase due to the dynamic addition and > removal of sleep scripts around off transitions might not be justifiable. Maybe Mike > does not want to hit 0V for Vdd's in the idle thread in which case it can be acceptable to > dynamically add the script in the system suspend path and remove it in the resume path. > Else I also do not think this approach is acceptable. I've missed the idle case indeed and I agree that dynamic addition and removal of sleep scripts is not an acceptable solution. > Regards > Thara > > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Sincerely yours, Mike.