On Friday 23 January 2015 17:55:25 Laurent Pinchart wrote:
>
> On Friday 23 January 2015 16:27:24 Arnd Bergmann wrote:
> > On Friday 23 January 2015 16:21:49 Laurent Pinchart wrote:
> > > +/**
> > > + * arm_iommu_detach_device
> > > + * @dev: valid struct device pointer
> > > + *
> > > + * Detaches the provided device from a previously attached map.
> > > + * This voids the dma operations (dma_map_ops pointer)
> > > + */
> > > +void arm_iommu_detach_device(struct device *dev)
> > > +{
> > > + __arm_iommu_detach_device(dev);
> > > + set_dma_ops(dev, NULL);
> > > +}
> > >
> > > EXPORT_SYMBOL_GPL(arm_iommu_detach_device);
> >
> > Would this introduce a regression in the case where the device is
> > cache coherent and needs arm_coherent_dma_ops set?
>
> I think we need to handle that case (as well as the coherent IOMMU case in
> arm_iommu_attach_device), but this patch only tries to restore the previous
> behaviour to fix the bug detailed in the commit message. Would you prefer
> fixing both issues in one go ?
>
No, I was specifically trying to find out whether the new behavior would
be worse than what we had in 3.18. If it's a preexisting bug that nobody
has run into, there is no hurry.
It's quite likely that to date, all IOMMU users on ARM32 are not
cache coherent.
Arnd
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