[Nouveau] [PATCH] pci: do a msi rearm on init

[Thierry Reding]

On Fri, Nov 24, 2017 at 03:56:26AM +0100, Karol Herbst wrote:
> On my GP107 when I load nouveau after unloading it, for some reason the
> GPU stopped sending or the CPU stopped receiving interrupts if MSI was
> enabled.

I suppose this could happen if the GPU raises an interrupt after the
driver's already called free_irq() on it, and hence the driver can't
rearm itself in the interrupt handler.

This possibly points to a bug somewhere (the GPU should be completely
idle by the time free_irq() is called), but this seems like a valid
thing to do at initialization in any case to avoid relying on the prior
owner of the device to always behave properly.

> Doing a rearm once before getting any interrupts fixes this.
> 
> Signed-off-by: Karol Herbst <kherbst at redhat.com>
> ---
>  drm/nouveau/nvkm/subdev/pci/base.c | 4 ++++
>  1 file changed, 4 insertions(+)

Reviewed-by: Thierry Reding <treding at nvidia.com>
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