From mboxrd@z Thu Jan 1 00:00:00 1970 From: grinberg@compulab.co.il (Igor Grinberg) Date: Sun, 15 Aug 2010 12:13:52 +0300 Subject: [Openpxa-users] Colibri PXA320 Power management question In-Reply-To: References: <201008140853.03174.marek.vasut@gmail.com> Message-ID: <4C67AFD0.4020304@compulab.co.il> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/15/10 05:06, Eric Miao wrote: > On Sat, Aug 14, 2010 at 2:53 PM, Marek Vasut wrote: > >> Dne ?t 12. srpna 2010 12:02:17 Yuri Ludkevich napsal(a): >> >>> Hi there :) >>> >>> I have a question about power management of Colibri PXA320 module: >>> I found that bits PVE and FVE in PVCR register are disabled, >>> so at frequency change voltage will not change. >>> >>> If I turn on PVE and FVE with pxaregs tool - voltage changes just fine. >>> Where are suitable place in the kernel for PVCR initialization? >>> >> I believe kernel should handle all that. Eric CCed. >> >> > Yep. Some of the design doesn't use the built-in power I2C at all, > they use some non-standard I2C power management IC. So this > should be handled in kernel indeed. The currently problem is that > we don't yet have a clean framework, some platforms are writing > directly to these registers to configure, which should be avoided. > If I recall correctly, the pxa3xx built-in power I2C control is designed for use with 100% compatible PMIC chip and if for some reason the hardware has another PMIC, which is not 100% compatible, then the built-in control can do more harm then good. I think we need a good and configurable DVFS driver to take care of all the power management stuff. > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- Regards, Igor.