On Fri, Nov 29, 2013 at 02:35:37AM +0100, Andreas Noever wrote:> > There are still a number of limitations: > (1) The system must be booted with acpi_osi=Darwin. Otherwise ACPI will cut > power to the controller. > (2) After suspend the controller is gone. I think that ACPI thinks that we > are > Windows and cuts power, even with acpi_osi=Darwin.
There's a few ACPI methods involved here. The first is DTLK, which is called by the firmware on resume. It'll cut power to the chip. So, you need to be able to power it back up. However, you only want to power it up if there's a device connected. The XRIL method will return 1 if there's a device connected and 0 otherwise. If there's a device connected, call XRPE with an argument of 1 to power it back up. That works fine if there's no hotplugging involved, but there is so things get a little more complicated. Apple provide an out of band mechanism for receiving notifications on the device. Call the _GPE method and install a gpe handler for the value that you get back. This will be called on every device plug or unplug (possibly just plug? It's been a while since I tested). Call XRIL to confirm that there's a device attached and then call XRPE to power it up. At least, that's my recollection. There's also the SXIO, SXIL, SXLV and SXFP methods that provide some kind of power management, but I'm not sure how those fit in. If you want to confirm that you're supposed to be using these methods, call _DSM on the device with a UUID of C6B7B5A0-1813-1C44-B0C9-FE695EAF949B (see DTGP in the DSDT), arg1 of 1, arg2 of 0. If it's an Apple you'll get back return value of 1 and a buffer containing the string "power-save". If it's not an Apple, or if the device doesn't support power saving, you'll get back a zero or an error that the method wasn't found. -- Matthew Garrett | mj...@srcf.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
