Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752013AbaKUSYY (ORCPT ); Fri, 21 Nov 2014 13:24:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53697 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbaKUSYV (ORCPT ); Fri, 21 Nov 2014 13:24:21 -0500 From: Alex Williamson Subject: [PATCH 2/4] PCI: quirk AMD/ATI VGA cards to avoid PM reset To: bhelgaas@google.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Alex Williamson , Alex Deucher Date: Fri, 21 Nov 2014 11:24:14 -0700 Message-ID: <20141121182414.26669.48397.stgit@gimli.home> In-Reply-To: <20141121180322.26669.65689.stgit@gimli.home> References: <20141121180322.26669.65689.stgit@gimli.home> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some AMD/ATI GPUs report that they support PM reset (NoSoftRst-) but initiating such a reset has no apparent affect on the device. The monitor remains sync'd, the framebuffer contents are retained, etc. Callers of pci_reset_function() don't necessarily have a way to validate whether a reset was effective, so we really want to avoid making use of a known non-effective reset. Returning an error in such cases appears to be the better option. For users like vfio-pci, this allows the driver to escalate to the bus reset interfaces. If a device lives on the root bus, there's really no further escalation path, so we exempt PM reset as potentially better than nothing. Signed-off-by: Alex Williamson Cc: Alex Deucher --- drivers/pci/quirks.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 90acb32..561e10d 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -3008,6 +3008,27 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_REALTEK, 0x8169, DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MELLANOX, PCI_ANY_ID, quirk_broken_intx_masking); +static void quirk_no_pm_reset(struct pci_dev *dev) +{ + /* + * A non-effective PM reset may be better than nothing + * if we can't do a bus reset + */ + if (!pci_is_root_bus(dev->bus)) + dev->dev_flags |= PCI_DEV_FLAGS_NO_PM_RESET; +} + +/* + * Some AMD/ATI GPUS (HD8570 - Oland) report supporting PM reset via D3->D0 + * transition (NoSoftRst-). This reset mechanims seems to have no effect + * whatsoever on the device, even retaining the framebuffer contents and + * monitor sync. Advertising this support makes other layers, like VFIO + * assume pci_reset_function() is viable for this device. Mark it as + * unavailable to skip it when testing reset methods. + */ +DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_VENDOR_ID_ATI, PCI_ANY_ID, + PCI_CLASS_DISPLAY_VGA, 8, quirk_no_pm_reset); + #ifdef CONFIG_ACPI /* * Apple: Shutdown Cactus Ridge Thunderbolt controller. -- 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/