[edk2-platforms][PATCH 1/1] Platform/RaspberryPi/RPi4: Add _DSM ACPI method for 32-bit MMIO xHCI access


Pete Batard
 

With the upcoming release of Windows 11, Microsoft has introduced a new USB
Device-Specific Method (_DSM) function to enforce 64-bit xHCI registers to
be accessed through two sequential 32-bit requests. The new function (Query
controller register access type - Function 6) is documented at:
https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/usb-devic=
e-specific-method---dsm-

Support for this feature is required on the raspberry Pi 4 where there is
a bug/limitation in the xHCI stack that prevents full range 64-bit access
from working correctly. It should be noted that an equivalent for this _DSM
is not required on Linux, as 64-bit xHCI register access is already broken
down into 2x32-bit by the drivers there.

With this _DSM, and unlike what is the case for Windows 10, Windows 11 can
now be installed on the Raspberry Pi 4 without having to alter any of the
installation files, as we were able to validate using the latest Windows 11
Build 22000 Insider image.

Signed-off-by: Pete Batard <pete@akeo.ie>
Tested-by: Pete Batard <pete@akeo.ie>
---
Platform/RaspberryPi/AcpiTables/Xhci.asl | 21 ++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/Platform/RaspberryPi/AcpiTables/Xhci.asl b/Platform/RaspberryP=
i/AcpiTables/Xhci.asl
index 9b37277956d9..00b0cd29c69c 100644
--- a/Platform/RaspberryPi/AcpiTables/Xhci.asl
+++ b/Platform/RaspberryPi/AcpiTables/Xhci.asl
@@ -138,6 +138,27 @@ DefinitionBlock (__FILE__, "SSDT", 5, "RPIFDN", "RPI4X=
HCI", 2)
Debug =3D "xHCI enable"=0D
Store (0x6, CMND)=0D
}=0D
+=0D
+ /*=0D
+ * Microsoft's USB Device-Specific Methods. See:=0D
+ * https://docs.microsoft.com/en-us/windows-hardware/drivers/bring=
up/usb-device-specific-method---dsm-=0D
+ */=0D
+ Name (DSMU, ToUUID ("ce2ee385-00e6-48cb-9f05-2edb927c4899"))=0D
+=0D
+ Method (_DSM, 4, Serialized) {=0D
+ If (LEqual (Arg0, DSMU)) { // USB capabilities UU=
ID=0D
+ Switch (ToInteger (Arg2)) {=0D
+ Case (0) { // Function 0: List of=
supported functions=0D
+ Return (Buffer () { 0x41 }) // 0x41 - Functions 0 =
and 6 supported=0D
+ }=0D
+ Case (6) { // Function 6: Registe=
rAccessType=0D
+ Return (Buffer () { 0x01 }) // 0x01 - Must use 32b=
it register access=0D
+ }=0D
+ Default { } // Unsupported=0D
+ }=0D
+ }=0D
+ return (Buffer () { 0x00 }) // Return 0x00 for any=
thing unsupported=0D
+ }=0D
} // end XHC0=0D
} //end SCB0=0D
} //end scope sb=0D
--=20
2.30.2.windows.1

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