> -----Original Message----- > From: Duran, Leo [mailto:leo.duran@xxxxxxx] > Sent: Wednesday, September 18, 2013 8:53 PM > To: Moore, Robert; 'Hanjun Guo' > Cc: Box, David E; 'linaro-kernel@xxxxxxxxxxxxxxxx'; 'patches@xxxxxxxxxx'; > 'linaro-acpi@xxxxxxxxxxxxxxxx'; 'Rafael J. Wysocki'; 'linux- > acpi@xxxxxxxxxxxxxxx'; Zheng, Lv; 'Len Brown' > Subject: RE: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware to > prevent accessing PM registers > > Ummh... > > > -----Original Message----- > > From: linaro-acpi-bounces@xxxxxxxxxxxxxxxx [mailto:linaro-acpi- > > bounces@xxxxxxxxxxxxxxxx] On Behalf Of Moore, Robert > > Sent: Wednesday, September 18, 2013 9:38 PM > > To: 'Hanjun Guo' > > Cc: Box, David E; 'linaro-kernel@xxxxxxxxxxxxxxxx'; > > 'patches@xxxxxxxxxx'; 'linaro-acpi@xxxxxxxxxxxxxxxx'; 'Rafael J. > > Wysocki'; 'linux-acpi@xxxxxxxxxxxxxxx'; Zheng, Lv; 'Len Brown' > > Subject: Re: [Linaro-acpi] [PATCH] ACPICA / hwreg: Use > > acpi_gbl_reduced_hardware to prevent accessing PM registers > > > > While we are at it, here is the *complete* list of ACPICA interfaces > > that are meaningless on a hardware-reduced platform. > > Events are supported by hw-reduced ACPI 5.0, just in a different (non- > legacy) way: GPIO-signaled events. > So I'm wondering if perhaps a bit of refactoring is in order, rather than > complete removal of all those functions? > Leo > GPIO events are drastically different than any other ACPI events. The model that ACPICA is using for these is that the native GPIO driver loads on detection of a GPIO _HID during the device detection namespace walk. Then: Text from the ACPI specification below. Comments in parentheses are mine: OSPM (GPIO driver) handles GPIO-signaled events as follows: * The GPIO interrupt is handled by OSPM (GPIO driver) because it is listed in the _AEI object under a GPIO controller. * When the event fires, OSPM (GPIO driver) handles the interrupt according to its mode and invokes the _EVT method (via AcpiEvaluateObject), passing it the pin number of the event. * From this point on, handling is exactly like that for GPEs. The _EVT method does a Notify() on the appropriate device, (AcpiInstallNotifyHandler) and OS-specific mechanisms are used to notify the driver of the event. None of the ACPICA interfaces below are required for this sequence of events. Bob > > If we are going to dynamically disable some of these interfaces, we > > will need to disable all of them -- for completeness. So, this is > > actually not a trivial change. > > > > I'll let the linux experts chime in on this one. > > Bob > > > > > > AcpiInstallSciHandler > > AcpiRemoveSciHandler > > AcpiInstallGlobalEventHandler > > AcpiInstallFixedEventHandler > > AcpiRemoveFixedEventHandler > > AcpiInstallGpeHandler > > AcpiRemoveGpeHandler > > AcpiAcquireGlobalLock > > AcpiReleaseGlobalLock > > AcpiEnable > > AcpiDisable > > AcpiEnableEvent > > AcpiDisableEvent > > AcpiClearEvent > > AcpiGetEventStatus > > AcpiUpdateAllGpes > > AcpiEnableGpe > > AcpiDisableGpe > > AcpiSetGpe > > AcpiSetupGpeForWake > > AcpiSetGpeWakeMask > > AcpiClearGpe > > AcpiGetGpeStatus > > AcpiFinishGpe > > AcpiDisableAllGpes > > AcpiEnableAllRuntimeGpes > > AcpiInstallGpeBlock > > AcpiRemoveGpeBlock > > AcpiGetGpeDevice > > AcpiGetTimerResolution > > AcpiGetTimer > > AcpiGetTimerDuration > > AcpiReadBitRegister > > AcpiWriteBitRegister > > AcpiSetFirmwareWakingVector > > AcpiSetFirmwareWakingVector64 > > AcpiEnterSleepStateS4bios > > > > > > > > > > > > > > > > > -----Original Message----- > > > From: Moore, Robert > > > Sent: Wednesday, September 18, 2013 8:09 AM > > > To: Hanjun Guo > > > Cc: 'Rafael J. Wysocki'; 'Len Brown'; Box, David E; Zheng, Lv; > > 'linux- > > > acpi@xxxxxxxxxxxxxxx'; 'patches@xxxxxxxxxx'; 'linaro- > > > kernel@xxxxxxxxxxxxxxxx'; 'linaro-acpi@xxxxxxxxxxxxxxxx' > > > Subject: RE: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware > > > to prevent accessing PM registers > > > > > > > > > > > > > -----Original Message----- > > > > From: Hanjun Guo [mailto:hanjun.guo@xxxxxxxxxx] > > > > Sent: Wednesday, September 18, 2013 2:32 AM > > > > To: Moore, Robert > > > > Cc: 'Rafael J. Wysocki'; 'Len Brown'; Box, David E; Zheng, Lv; > > 'linux- > > > > acpi@xxxxxxxxxxxxxxx'; 'patches@xxxxxxxxxx'; 'linaro- > > > > kernel@xxxxxxxxxxxxxxxx'; 'linaro-acpi@xxxxxxxxxxxxxxxx' > > > > Subject: Re: [PATCH] ACPICA / hwreg: Use acpi_gbl_reduced_hardware > > to > > > > prevent accessing PM registers > > > > > > > > On 2013-9-17 1:26, Moore, Robert wrote: > > > > > + #define ACPI_REDUCED_HARDWARE TRUE > > > > > > > > > > The intent of this feature is of course, to remove all code that > > is > > > > > not > > > > needed -- specifically for hardware-reduced machines where the > > > > size > > of > > > > the kernel is important. > > > > > > > > > > On a larger machine, the hardware-reduced flag should be > > sufficient. > > > > However, I would think that the host OS would look at this flag > > > > and realize that it should not be doing certain ACPI > > > > hardware-related things up front, rather than later when it finds > > > > out that a write > > to > > > > some ACPI hardware fails because the hardware isn't there. > > > > > > > > Do you mean we should change the ACPI device driver instead of > > > > changing the ACPICA code? that would be a hard job, because > > hardware > > > > ACPI is used everywhere. > > > > > > > > > > > > > I don't really know the answer to this, but something tells me that > > bad > > > things may happen when a driver expects the ACPI hardware to be > > there, and > > > it finds out that it isn't, simply by calling one of the ACPI > > hardware > > > interfaces. > > > > > > Or, we could word it this way: if a driver is expecting the ACPI > > hardware > > > to exist, and we are running on a hardware-reduced platform, why is > > the > > > driver being loaded in the first place? > > > > > > BTW, hardware-reduced is not restricted to ARM platforms. > > > > > > > > > > > > > > > > Thanks > > > > Hanjun > > > > > > > > > > > > > > This is not to say that it is probably a good thing to return an > > > > > error > > > > from the ACPI hardware code in the hardware-reduced case. > > > > > > > > > > Bob > > > > > > > > > > > > > > > _______________________________________________ > > Linaro-acpi mailing list > > Linaro-acpi@xxxxxxxxxxxxxxxx > > http://lists.linaro.org/mailman/listinfo/linaro-acpi > -- 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
