From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754214AbcISJ3C (ORCPT ); Mon, 19 Sep 2016 05:29:02 -0400 Received: from mail-pf0-f178.google.com ([209.85.192.178]:35355 "EHLO mail-pf0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751414AbcISJ2y (ORCPT ); Mon, 19 Sep 2016 05:28:54 -0400 Subject: Re: [RFC PATCH v2 10/11] irqchip: mbigen: Add ACPI support To: Marc Zyngier , Hanjun Guo , "Rafael J. Wysocki" , Lorenzo Pieralisi References: <1473862879-7769-1-git-send-email-guohanjun@huawei.com> <1473862879-7769-11-git-send-email-guohanjun@huawei.com> <57DA6097.8060105@arm.com> Cc: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Bjorn Helgaas , Greg KH , Tomasz Nowicki , Ma Jun , Kefeng Wang , Charles Garcia-Tobin , linuxarm@huawei.com From: Hanjun Guo Message-ID: Date: Mon, 19 Sep 2016 17:28:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <57DA6097.8060105@arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 2016/9/15 16:49, Marc Zyngier wrote: > On 14/09/16 15:21, Hanjun Guo wrote: >> From: Hanjun Guo >> >> 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