From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <5344679E.1030008@pobox.com> Date: Tue, 08 Apr 2014 17:18:22 -0400 From: Mark Lord MIME-Version: 1.0 To: Bjorn Helgaas CC: "linux-kernel@vger.kernel.org" , Yinghai Lu , Theodore Ts'o , "linux-pci@vger.kernel.org" , Benjamin Herrenschmidt Subject: Re: driver skip pci_set_master, fix it? No. References: <5344251D.7040805@pobox.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: On 14-04-08 02:27 PM, Bjorn Helgaas wrote: > [+cc Ben, linux-pci] > > On Tue, Apr 8, 2014 at 10:34 AM, Mark Lord wrote: >> I am working a couple of drivers for chips that perform extensive bus-mastering ops. >> These including full SRIOV support, and allow assigning virtual functions to virtual machines, etc. >> >> One thing the driver (still in development) does for safety, >> is defer the call to pci_set_master() until *after* it has mapped >> the MMIO space of the chips, so it can reset/flush the DMA engines >> before giving them permission to scribble over host RAM. >> >> But a recent patch to the kernel has removed this from the driver's control. >> The core PCI now does pci_set_master() immediately on pci_enable_device(). > > I assume you're talking about the one added by cf3e1feba7f9 ("PCI: > Workaround missing pci_set_master in pci drivers"), but as far as I > can tell, it only calls pci_set_master() for *bridge* devices. What > am I missing? Is pci_set_master() being called for your endpoint? > What path is that? Yes, it is being called during execution of the _probe() function in my driver, as evidenced by the annoying (and wrong) message it produces. Next time I've got the hardware at hand, I'll put a "dump_stack()" into there to see the exact calling path. -- Mark Lord Real-Time Remedies Inc. mlord@pobox.com