From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e24smtp05.br.ibm.com ([32.104.18.26]:50809 "EHLO e24smtp05.br.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932073Ab2JSRnf (ORCPT ); Fri, 19 Oct 2012 13:43:35 -0400 Received: from /spool/local by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 19 Oct 2012 14:43:32 -0300 Message-ID: <50819140.8030806@linux.vnet.ibm.com> Date: Fri, 19 Oct 2012 14:43:28 -0300 From: Lucas Kannebley Tavares MIME-Version: 1.0 To: dri-devel@lists.freedesktop.org CC: David Airlie , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Brian King , Benjamin Herrenschmidt , Nishanth Aravamudan Subject: radeon: RFC speed cap detection on ppc64 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: The radeon driver does speed cap detection on the root PCI device for the maximum speed with which the adapter can communicate. On ppc64 systems, however, the root device belongs to the Hypervisor, so the current code would case a null pointer dereference. I propose to look for the outmost bus with a parent node and get speed caps from it, though I suppose the cleaner way would be to inspect all devices along the way and choose the smallest speed cap. Does anyone have suggestions for this? Thanks -- --- /home/lucaskt/work/devdrivers/kernel/linux/drivers/gpu/drm/drm_pci.c 2012-09-26 10:06:00.280549928 -0300 +++ drm_pci.c 2012-09-26 15:38:51.121786353 -0300 @@ -466,6 +466,19 @@ } EXPORT_SYMBOL(drm_pci_exit); +static struct pci_dev *drm_get_pcie_root_dev(struct pci_dev *dev) +{ + // Go up through all possible busses to get the info for the outmost bus + while (!pci_is_root_bus(dev->bus)) + dev = dev->bus->parent->self; + + // In POWER architectures there's no PCI root device, so it should just read + // the caps from the device itself + if (dev->bus->self != NULL) + return dev->bus->self; + else + return dev; +} + int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask) { struct pci_dev *root; @@ -479,7 +492,7 @@ if (!pci_is_pcie(dev->pdev)) return -EINVAL; - root = dev->pdev->bus->self; + root = drm_get_pcie_root_dev(dev->pdev); pos = pci_pcie_cap(root); if (!pos) -- Lucas Kannebley Tavares Software Engineer IBM Linux Technology Center