From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758281AbbFADJu (ORCPT ); Sun, 31 May 2015 23:09:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51396 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751232AbbFADJn (ORCPT ); Sun, 31 May 2015 23:09:43 -0400 Date: Mon, 1 Jun 2015 11:09:40 +0800 From: Baoquan He To: Joerg Roedel Cc: linux-kernel@vger.kernel.org Subject: A question about state machine function state_next() Message-ID: <20150601030940.GK6353@dhcp-128-28.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Joerg, I am reading amd iommu code because I have some knowledge about intel iommu since review Zhenhua's fixing kdump error patches. Now there's a question I didn't find answer. In amd iommu state_next() is the state machine running function. However I only found 4 function to call iommu_go_to_state() to change the state, they are: amd_iommu_detect() amd_iommu_prepare() amd_iommu_enable() amd_iommu_init() And they are called according to above sequence. It means only below 4 cases are checked and the code blocks are executed. Then where to call amd_iommu_enable_interrupts() and amd_iommu_init_dma(). Could you help to tell what I missed? static int __init state_next(void) { int ret = 0; switch (init_state) { case IOMMU_START_STATE: //checked and execute case IOMMU_IVRS_DETECTED: //checked and execute case IOMMU_ACPI_FINISHED: //checked and execute case IOMMU_ENABLED: //checked and execute ... } Thanks Baoquan