Messages in this thread | | | Subject | Re: [RFC PATCH v2 10/11] irqchip: mbigen: Add ACPI support | From | Hanjun Guo <> | Date | Mon, 19 Sep 2016 17:28:33 +0800 |
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Hi Marc,
On 2016/9/15 16:49, Marc Zyngier wrote: > On 14/09/16 15:21, Hanjun Guo wrote: >> From: Hanjun Guo <hanjun.guo@linaro.org> >> >> With the preparation of platform msi support and interrupt producer >> in DSDT, we can add mbigen ACPI support now. >> >> We are using _PRS methd to indicate number of irq pins instead >> of num_pins in DT. >> >> For mbi-gen, >> Device(MBI0) { >> Name(_HID, "HISI0152") >> Name(_UID, Zero) >> Name(_CRS, ResourceTemplate() { >> Memory32Fixed(ReadWrite, 0xa0080000, 0x10000) >> }) >> >> Name (_PRS, ResourceTemplate() { >> Interrupt(ResourceProducer,...) {12,14,....} >> }) > > Since I know next to nothing about all of this, I'm going to play the > village idiot. What makes it legal to use _PRS as a way to describe the > interrupts that are exposed by MBI0? Looking at the 6.0 spec, I do not > see why the interrupts would be put there instead of _CRS, and why you'd > have a _PRS at all.
_PRS describes possible resource settings for the device, which returns a list of a device's possible resource settings such as memory range, interrupt descriptors, and the format of the data in a _PRS object follows the same format as _CRS object (ACPI 6.1, section 6.2.12), so Interrupts can be put in the _PRS.
And in ACPI 6.1, section 6.2, it describes the _PRS usage:
"Some resources, however, may be shared amongst several devices. To describe this, devices that share a resource (resource consumers) must use the extended resource descriptors (0x7-0xA) described in Section 6.4.3, “Large Resource Data Type.” These descriptors point to a single device object (resource producer) that claims the shared resource in its _PRS."
As mbigen is a interrupt producer which provide interrupt resoures for devices, which matches the usage of _PRS in the spec.
> > Also, are you going to exhaustively describe all the possible interrupts > via this method? Knowing that the mbigen can expose thousands of > interrupts, I find it slightly mad. Can't you express a range?
Yes, a little bit mad. I can't express a interrupt range in ACPI at least in current version of spec. But that just adding more lines of ACPI DSDT code, it's fine to me. or we need to use _DSD to present similar property "num_pins" in ACPI which I avoid using.
Thanks Hanjun
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