Hi,
On 4/29/20 4:21 PM, Andy Shevchenko wrote:
On Wed, Apr 29, 2020 at 12:46:51PM +0200, Hans de Goede wrote:
On Cherry Trail devices there are 2 possible ACPI OpRegions for accessing GPIOs. The standard GeneralPurposeIo OpRegion and the Cherry Trail specific UserDefined 0x9X OpRegions.
Having 2 different types of OpRegions leads to potential issues with checks for OpRegion availability, or in other words checks if _REG has been called for the OpRegion which the ACPI code wants to use.
The ACPICA core does not call _REG on an ACPI node which does not define an OpRegion matching the type being registered; and the reference design DSDT, from which most Cherry Trail DSDTs are derived, does not define GeneralPurposeIo, nor UserDefined(0x93) OpRegions for the GPO2 (UID 3) device, because no pins were assigned ACPI controlled functions in the reference design.
Together this leads to the perfect storm, at least on the Cherry Trail based Medion Akayo E1239T. This design does use a GPO2 pin from its ACPI code and has added the Cherry Trail specific UserDefined(0x93) opregion to its GPO2 ACPI node to access this pin.
But it uses a has _REG been called availability check for the standard GeneralPurposeIo OpRegion. This clearly is a bug in the DSDT, but this does work under Windows. This issue leads to the intel_vbtn driver reporting the device always being in tablet-mode at boot, even if it is in laptop mode. Which in turn causes userspace to ignore touchpad events. So iow this issues causes the touchpad to not work at boot.
Since the bug in the DSDT stems from the confusion of having 2 different OpRegion types for accessing GPIOs on Cherry Trail devices, I believe that this is best fixed inside the cherryview pinctrl driver.
This commit adds a workaround to the cherryview pinctrl driver so that the DSDT's expectations of _REG always getting called for the GeneralPurposeIo OpRegion are met.
s/cherryview/Cherryview/g
Fixed for v2.
...
- if (acpi_has_method(adev->handle, "_REG")) {
And this check si redundant, you may call it as is (you didn't check for error anyway), see also below.
Good point, also dropped for v2.
struct acpi_object_list input;union acpi_object params[2];input.count = 2;input.pointer = params;params[0].type = ACPI_TYPE_INTEGER;params[0].integer.value = ACPI_ADR_SPACE_GPIO;params[1].type = ACPI_TYPE_INTEGER;params[1].integer.value = 1;acpi_evaluate_object(adev->handle, "_REG", &input, NULL);- }
Can you consider to unify this with one in drivers/pci/hotplug/acpiphp_glue.c, so we will have some helper function at the end? (perhaps as separate changes to make less burden on backporting this one)
I think that for backporting it is best to keep this patch as is (with your other comments addresed). Also this way this can hopefully be merged for a 5.7-rc# candidate.
I will do a follow up series adding a helper and moving both cases over to the helper.
Regards,
Hans