From mboxrd@z Thu Jan 1 00:00:00 1970 From: zonque@gmail.com (Daniel Mack) Date: Mon, 29 Oct 2012 12:00:55 +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> Message-ID: <508E61E7.7090502@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 29.10.2012 11:52, Vasily Khoruzhick wrote: > On Mon, Oct 29, 2012 at 1:44 PM, Daniel Mack wrote: > >> I haven't seen any patches for DT bindings of this yet. >> >>> I still don't understand how DT handles platform-specific >>> callbacks like set_power(). And what about pm_power_off hook? >> >> They require consideration. >> >> In general, a driver should be aware of everything that affects the >> peripheral, including all the voltages and clocks it needs and also all >> extra pins like for example reset GPIOs etc. And all that properties are >> to be exported via DT as well (things that you would have normally set >> up using pdata). >> >> If drivers lack that kind of full awareness of their environment, they >> need to be augmented, because - to stick with the example of reset GPIOs >> - the driver of all parts is the only piece that knows when to driver >> that pin and how. >> >> About the hack to put the z2 to deep-sleep when it should actually power >> down, I don't know what to do. But I would say that it's the userspace >> that should be fixed here, if possible. > > 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?