[PATCH 1/4] powerpc: Dynamic DMA zone limits
scottwood at freescale.com
Tue Oct 14 18:39:06 AEDT 2014
On Mon, 2014-10-13 at 20:00 +1100, Michael Ellerman wrote:
> On Mon, 2014-10-13 at 18:14 +1100, Anton Blanchard wrote:
> > Hi Scott,
> > > Platform code can call limit_zone_pfn() to set appropriate limits
> > > for ZONE_DMA and ZONE_DMA32, and dma_direct_alloc_coherent() will
> > > select a suitable zone based on a device's mask and the pfn limits
> > > that platform code has configured.
> > This patch breaks my POWER8 box:
> > ipr 0001:08:00.0: Using 64-bit DMA iommu bypass
> > ipr 0001:08:00.0: dma_direct_alloc_coherent: No suitable zone for pfn 0x10000
> > ipr 0001:08:00.0: Couldn't allocate enough memory for device driver!
> > ipr: probe of 0001:08:00.0 failed with error -12
> > ipr isn't setting a coherent mask, but we shouldn't care on these boxes.
> > Could we ignore the coherent mask or copy the dma mask to it?
> Talking to Ben the answer seems to be "it's complicated".
> We shouldn't be ignoring the coherent mask, but we have been, and have been
> getting away with it.
> The PCI code sets a default 32-bit mask, so we can't even detect when a device
> hasn't set it. Though maybe the powernv PCI code could be initialising it to
> 64-bit ?
> For this cycle I'm thinking of the below patch.
> Scott & Anton can you test please?
> Also the depends on FSL_PCI was totally a guess, so please correct that if it's
> wrong Scott.
We need the DMA zone for non-PCI devices, so FSL_SOC would be a better
> diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
> index adac9dc54aee..bd443a2e4426 100644
> --- a/arch/powerpc/kernel/dma.c
> +++ b/arch/powerpc/kernel/dma.c
> @@ -53,6 +53,7 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
> struct page *page;
> int node = dev_to_node(dev);
> +#ifdef CONFIG_ZONE_DMA32
> u64 pfn = get_pfn_limit(dev);
> int zone;
> @@ -67,12 +68,11 @@ void *dma_direct_alloc_coherent(struct device *dev, size_t size,
> case ZONE_DMA:
> flag |= GFP_DMA;
> -#ifdef CONFIG_ZONE_DMA32
> case ZONE_DMA32:
> flag |= GFP_DMA32;
> +#endif /* CONFIG_ZONE_DMA32 */
For a short-term workaround, I'd rather leave CONFIG_ZONE_DMA32 where it
is and put #ifdef CONFIG_FSL_SOC (with a comment) around the whole
More information about the Linuxppc-dev