From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757342AbaFYOIt (ORCPT ); Wed, 25 Jun 2014 10:08:49 -0400 Received: from mail-ve0-f170.google.com ([209.85.128.170]:54357 "EHLO mail-ve0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757253AbaFYOIs (ORCPT ); Wed, 25 Jun 2014 10:08:48 -0400 MIME-Version: 1.0 In-Reply-To: References: <1403688530-23273-1-git-send-email-marc.zyngier@arm.com> <1403688530-23273-4-git-send-email-marc.zyngier@arm.com> From: Rob Herring Date: Wed, 25 Jun 2014 09:08:27 -0500 Message-ID: Subject: Re: [RFC PATCH 3/9] irqchip: GIC: Convert to EOImode == 1 To: Anup Patel Cc: Marc Zyngier , Ian Campbell , Catalin Marinas , Will Deacon , "linux-kernel@vger.kernel.org List" , Thomas Gleixner , "kvmarm@lists.cs.columbia.edu" , linux-arm-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 25, 2014 at 8:56 AM, Anup Patel wrote: > Hi Marc, > > On Wed, Jun 25, 2014 at 2:58 PM, Marc Zyngier wrote: >> So far, GICv2 has been used in with EOImode == 0. The effect of this >> mode is to perform the priority drop and the deactivation of the >> interrupt at the same time. >> >> While this works perfectly for Linux (we only have a single priority), >> it causes issues when an interrupt is forwarded to a guest, and when >> we want the guest to perform the EOI itself. >> >> For this case, the GIC architecture provides EOImode == 1, where: >> - A write to the EOI register drops the priority of the interrupt and leaves >> it active. Other interrupts at the same priority level can now be taken, >> but the active interrupt cannot be taken again >> - A write to the DIR marks the interrupt as inactive, meaning it can >> now be taken again. >> >> We only enable this feature when booted in HYP mode. Also, as most device >> trees are broken (they report the CPU interface size to be 4kB, while >> the GICv2 CPU interface size is 8kB), output a warning if we're booted >> in HYP mode, and disable the feature. >> >> Signed-off-by: Marc Zyngier >> --- [...] >> + if (resource_size(&cpu_res) >= SZ_8K) >> + supports_deactivate = true; >> + else >> + pr_warn("GIC: CPU interface size is %x, DT is probably wrong\n", (int)resource_size(&cpu_res)); > > This will not work on APM X-Gene because, for > X-Gene first CPU page is at 0x78020000 and > second CPU page is at 0x78030000. Does 0x7802f000 for the cpu address not work? It should if X-Gene is "SBSA compliant" for whatever that is worth. Rob