On Thu, 2013-11-21 at 00:08 +0000, Russell King - ARM Linux wrote: > On Thu, Nov 21, 2013 at 11:01:42AM +1100, Benjamin Herrenschmidt wrote: > > On Wed, 2013-11-20 at 23:23 +0000, Russell King - ARM Linux wrote: > > > Li Zong's patch works around the issue of a failing dma_set_mask(), > > > but as I've already said elsewhere, the real fix is to get whatever > > > created the struct device to initialise the dev->dma_mask with a > > > bus default. > > > > > > Using dma_coerce_xxx() merely makes the problem "go away" papering > > > over the issue - it's fine to do it this way, but someone should still > > > fix the broken code creating these devices... > > > > Ok, they are created by the vio bus core, so it should be doing the > > job here of setting the dma_mask pointer to a proper value. > > > > Li, can you take care of that ? Look at other bus types we have in > > there such as the macio bus etc... > > Oh, hang on a moment, this is the "bus" code. > > In which case, the question becomes: do vio devices ever need to have > a separate streaming DMA mask from a coherent DMA mask? If not, then > something like the following is what's needed here, and I should've > never have used dma_set_mask_and_coherent().
No, a single mask. > dma_set_mask_and_coherent() (and the other dma_set_mask() functions) > are really supposed to be used by drivers only. > > arch/powerpc/kernel/vio.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/powerpc/kernel/vio.c b/arch/powerpc/kernel/vio.c > index e7d0c88f621a..d771778f398e 100644 > --- a/arch/powerpc/kernel/vio.c > +++ b/arch/powerpc/kernel/vio.c > @@ -1419,7 +1419,8 @@ struct vio_dev *vio_register_device_node(struct > device_node *of_node) > > /* needed to ensure proper operation of coherent allocations > * later, in case driver doesn't set it explicitly */ > - dma_set_mask_and_coherent(&viodev->dev, DMA_BIT_MASK(64)); > + viodev->dev.coherent_dma_mask = DMA_BIT_MASK(64); > + viodev->dev.dma_mask = &viodev->dev.coherent_dma_mask; > } > > /* register with generic device framework */ Right that's exactly what I had in mind. Li, can you test this please ? The previous "fix" using dma_coerce_mask_and_coherent() is already on its way to Linus, so we'll rework the above patch to undo it but for now please test. Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
