Messages in this thread | | | From | Sangbeom Kim <> | Subject | RE: [PATCH 5/5] regulator: Support AP watchdog reset operation for s5m8767a | Date | Thu, 14 Jun 2012 09:01:39 +0900 |
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Hi Mark, I'm sorry for insufficient explanation. Basically, PMIC can't know status of ap reset. Problem can be happened like below.
- AP Bootable lowest arm voltage: 0.9v - AP arm voltage table for DVFS: 0.8v, 0.9v, 1.0v - During AP works on 0.8v, watchdog reset is asserted - AP can't boot, because vdd arm is still 0.8v
Solution - Basic concept: After ap watchdog reset, GPIO configuration is changed by default value - S5M8767A has function of voltage control with gpio (8 levels with 3 gpios) - Set bootable voltage on level 0 -> can work with default gpio configuration - In the probing, Change voltage control level from level 0 to level 1 - Execute normal dvfs operation on level 1 - After watchdog reset, ap gpio is set by default value - PMIC operation mode is changed by ap reset (level1 -> level0) - AP can execute normal boot
If you have any question, email me again. Thanks, Sangbeom.
> -----Original Message----- > From: Mark Brown [mailto:broonie@opensource.wolfsonmicro.com] > Sent: Thursday, June 14, 2012 2:46 AM > To: Sangbeom Kim > Cc: 'Liam Girdwood'; linux-kernel@vger.kernel.org; sameo@linux.intel.com; sbkim01@gmail.com > Subject: Re: [PATCH 5/5] regulator: Support AP watchdog reset operation for s5m8767a > > On Wed, Jun 13, 2012 at 05:28:47PM +0900, Sangbeom Kim wrote: > > After AP watchdog reset, S5M8767A should be reset too. > > If AP is set on lowest voltage, AP can't execute boot sequence. > > This patch support watchdog reset of s5m8767. > > It's really hard to see how this patch addresses the issue above - could you explain in more > detail, please?
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