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SubjectRe: driver skip pci_set_master, fix it? No.
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.

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