On Wed, 22 Oct 2014, Stefano Stabellini wrote: > On Mon, 13 Oct 2014, Stefano Stabellini wrote: > > On Mon, 13 Oct 2014, Will Deacon wrote: > > > On Mon, Oct 13, 2014 at 12:16:14PM +0100, Stefano Stabellini wrote: > > > > On Fri, 10 Oct 2014, Stefano Stabellini wrote: > > > > > On Fri, 10 Oct 2014, Will Deacon wrote: > > > > > > On Fri, Oct 10, 2014 at 12:51:44PM +0100, Stefano Stabellini wrote: > > > > > > > Introduce a function to check whether a device is dma coherent. > > > > > > > > > > > > > > Signed-off-by: Stefano Stabellini > > > > > > > <[email protected]> > > > > > > > CC: [email protected] > > > > > > > CC: [email protected] > > > > > > > CC: [email protected] > > > > > > > CC: [email protected] > > > > > > > --- > > > > > > > arch/arm/include/asm/dma-mapping.h | 6 ++++++ > > > > > > > arch/arm64/include/asm/dma-mapping.h | 5 +++++ > > > > > > > 2 files changed, 11 insertions(+) > > > > > > > > > > > > > > diff --git a/arch/arm/include/asm/dma-mapping.h > > > > > > > b/arch/arm/include/asm/dma-mapping.h > > > > > > > index c45b61a..bededbb 100644 > > > > > > > --- a/arch/arm/include/asm/dma-mapping.h > > > > > > > +++ b/arch/arm/include/asm/dma-mapping.h > > > > > > > @@ -126,6 +126,12 @@ static inline int > > > > > > > set_arch_dma_coherent_ops(struct device *dev) > > > > > > > set_dma_ops(dev, &arm_coherent_dma_ops); > > > > > > > return 0; > > > > > > > } > > > > > > > + > > > > > > > +static inline bool is_dma_coherent(struct device *dev) > > > > > > > +{ > > > > > > > + return (__generic_dma_ops(dev) == &arm_coherent_dma_ops); > > > > > > > +} > > > > > > > > > > > > Hmm, what about the IOMMU ops? > > > > > > > > > > Maybe I should check __generic_dma_ops(dev) != &arm_dma_ops? > > > > > Do you have any better suggestions? > > > > > > > > ping? > > > > > > Without any clear idea about why this is needed or how it's used, I don't > > > have any better ideas. > > > > Thanks for the quick reply. > > > > It is used in dom0 to figure out whether the device is not coherent: in > > that case Dom0 is going to issue an hypercall and Xen is going to > > execute the required cache maintenance operations on Dom0's behalf. > > > > In practice for this use case iommu_dma_ops is not a problem, as the > > device is never going to appear as being behind an SMMU in dom0. > > re-ping?
I don't mean to be pushy but this series is required to fix a regression that causes dom0 to crash when running as dom0 on Xen on ARM if non-coherent devices are present on the platform. We should aim at getting it in 3.18 or we are going to release a broken kernel. I am thinking of reposting the series keeping the ugly is_dma_coherent function in a Xen specific source file as a static function and then fix it up properly in common code later with your help? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
