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@xxxxxxxxxx> 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 -- 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
