Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757745AbaFSJzb (ORCPT ); Thu, 19 Jun 2014 05:55:31 -0400 Received: from mga11.intel.com ([192.55.52.93]:33895 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757323AbaFSJz3 (ORCPT ); Thu, 19 Jun 2014 05:55:29 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,506,1400050800"; d="scan'208";a="557874894" From: Tiejun Chen To: daniel.vetter@ffwll.ch, jani.nikula@linux.intel.com, airlied@linux.ie Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, qemu-devel@nongnu.org Subject: [RFC][PATCH] gpu:drm:i915:intel_detect_pch: back to check devfn instead of check class type Date: Thu, 19 Jun 2014 17:53:51 +0800 Message-Id: <1403171631-3452-1-git-send-email-tiejun.chen@intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Originally the reason to probe ISA bridge instead of Dev31:Fun0 is to make graphics device passthrough work easy for VMM, that only need to expose ISA bridge to let driver know the real hardware underneath. This is a requirement from virtualization team. Especially in that virtualized environments, XEN, there is irrelevant ISA bridge in the system with that legacy qemu version specific to xen, qemu-xen-traditional. So to work reliably, we should scan through all the ISA bridge devices and check for the first match, instead of only checking the first one. But actually, qemu-xen-traditional, is always enumerated with Dev31:Fun0, 00:1f.0 as follows: hw/pt-graphics.c: intel_pch_init() | + pci_isa_bridge_init(bus, PCI_DEVFN(0x1f, 0), ...); so this mean that isa bridge is still represented with Dev31:Func0 like the native OS. Furthermore, currently we're pushing VGA passthrough support into qemu upstream, and with some discussion, we wouldn't set the bridge class type and just expose this devfn. So we just go back to check devfn to make life normal. Signed-off-by: Tiejun Chen --- drivers/gpu/drm/i915/i915_drv.c | 19 +++---------------- 1 file changed, 3 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index 651e65e..cb2526e 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -417,18 +417,8 @@ void intel_detect_pch(struct drm_device *dev) return; } - /* - * The reason to probe ISA bridge instead of Dev31:Fun0 is to - * make graphics device passthrough work easy for VMM, that only - * need to expose ISA bridge to let driver know the real hardware - * underneath. This is a requirement from virtualization team. - * - * In some virtualized environments (e.g. XEN), there is irrelevant - * ISA bridge in the system. To work reliably, we should scan trhough - * all the ISA bridge devices and check for the first match, instead - * of only checking the first one. - */ - while ((pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, pch))) { + pch = pci_get_bus_and_slot(0, PCI_DEVFN(0x1f, 0)); + if (pch) { if (pch->vendor == PCI_VENDOR_ID_INTEL) { unsigned short id = pch->device & INTEL_PCH_DEVICE_ID_MASK; dev_priv->pch_id = id; @@ -462,10 +452,7 @@ void intel_detect_pch(struct drm_device *dev) DRM_DEBUG_KMS("Found LynxPoint LP PCH\n"); WARN_ON(!IS_HASWELL(dev)); WARN_ON(!IS_ULT(dev)); - } else - continue; - - break; + } } } if (!pch) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/