On Wednesday, May 13, 2015 01:07:36 PM Al Stone wrote: > On 05/13/2015 10:25 AM, Adam Goode wrote: > > The Macmini7,1 addresses SystemCMOS memory in _INI methods. Currently, > > this fails since _INI is called before the acpi_cmos_rtc_space_handler > > is registered. > > > > I proposed registering a default handler on the ACPICA list, but was > > told that because the device has a _HID it should require a device > > driver. > > > > So, is it possible to register a device driver before _INI is called? > > Otherwise, Thunderbolt doesn't get initialized properly on this > > hardware. > > I take it from the question that the _INI methods are using the predefined > SystemCMOS OperationRegion, correct? Are the _INI methods invoking _REG > before trying to access that region? Looking at the spec, the _INI methods > must first call _REG to see if SystemCMOS is available for use (see section > 6.5.1), and there is no requirement that SystemCMOS must be available for > use by _INI (see 6.5.4). So, if I think about this from the spec point of > view, it sounds like the _INI methods are non-compliant. From the kernel > perspective, the SystemCMOS region is created at a reasonable time and is > available when it is required to be. > > It seems to me that the correct answer is that there should indeed be a device > driver connected to the _HID, but that it gets invoked just like any other > driver, and has as part of its probe an invocation of some method to access > the necessary items in the SystemCMOS (maybe add the method in an SSDT loaded > at run-time?). One could also hack around this by moving where in the kernel > the SystemCMOS region gets created to some place before the _INI functions are > invoked, but that feels klunky to me to handle firmware that may not be correct. There may be another way: Add a DMI quirk for the affected Apple system to acpi_cmos_rtc.c that would install the address space handler early (ie. before _INI is executed) and make acpi_install_cmos_rtc_space_handler() return immediately if the address space handler is already installed. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
