From mboxrd@z Thu Jan 1 00:00:00 1970 From: zonque@gmail.com (Daniel Mack) Date: Mon, 29 Oct 2012 12:14:34 +0100 Subject: [PATCH 2/5] ARM: PXA: Zipit Z2: Add USB host and device support In-Reply-To: References: <1351438555-4668-1-git-send-email-anarsoul@gmail.com> <1351438555-4668-2-git-send-email-anarsoul@gmail.com> <201210282259.46491.marex@denx.de> <508E4F7F.7010607@gmail.com> <508E5DFB.3060002@gmail.com> <508E61E7.7090502@gmail.com> Message-ID: <508E651A.5070009@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 29.10.2012 12:12, Vasily Khoruzhick wrote: > On Mon, Oct 29, 2012 at 2:00 PM, Daniel Mack wrote: > >>> Well, there's an issue - Z2 does not preserve memory contents in deep sleep >>> (but it does in sleep), so userspace can't be fixed here unfortunatelly. >>> There's no another possibility to turn Z2 off, and plain sleep is too >>> power hungry. >>> So the only way to keep Z2 in low-power mode is fake power off, which just puts >>> Z2 in deep sleep. >> >> Why can't the userspace trigger a deep sleep then instead of powering >> off? Which details do I lack? > > How? echo mem >/sys/power/state puts system into non-deep sleep. Anyway, kernel > is not ready for fake power off instead of suspend (we can't resume > from deep sleep, > memory content is not preserved), so there can be some data loss. > Adding some sysfs file to control sleep type does not look like a good > idea to me. > > Btw, how other DT-capable boards handle power off? No idea. I never actually used that kind of power state.