linux-toradex.git/arch/powerpc/kernel/dma.c, branch v4.3-rc2

powerpc/powernv: move dma_get_required_mask from pnv_phb to pci_controller_ops

2015-08-18T09:32:11+00:00

Simplify the dma_get_required_mask call chain by moving it from pnv_phb to
pci_controller_ops, similar to commit 763d2d8df1ee ("powerpc/powernv:
Move dma_set_mask from pnv_phb to pci_controller_ops").

Previous call chain:

  0) call dma_get_required_mask() (kernel/dma.c)
  1) call ppc_md.dma_get_required_mask, if it exists. On powernv, that
     points to pnv_dma_get_required_mask() (platforms/powernv/setup.c)
  2) device is PCI, therefore call pnv_pci_dma_get_required_mask()
     (platforms/powernv/pci.c)
  3) call phb->dma_get_required_mask if it exists
  4) it only exists in the ioda case, where it points to
       pnv_pci_ioda_dma_get_required_mask() (platforms/powernv/pci-ioda.c)

New call chain:

  0) call dma_get_required_mask() (kernel/dma.c)
  1) device is PCI, therefore call pci_controller_ops.dma_get_required_mask
     if it exists
  2) in the ioda case, that points to pnv_pci_ioda_dma_get_required_mask()
     (platforms/powernv/pci-ioda.c)

In the p5ioc2 case, the call chain remains the same -
dma_get_required_mask() does not find either a ppc_md call or
pci_controller_ops call, so it calls __dma_get_required_mask().

Signed-off-by: Andrew Donnellan 
Reviewed-by: Daniel Axtens 
Signed-off-by: Michael Ellerman

powerpc/iommu: Support "hybrid" iommu/direct DMA ops for coherent_mask < dma_mask

2015-07-13T00:10:55+00:00

This patch adds the ability to the DMA direct ops to fallback to the IOMMU
ops for coherent alloc/free if the coherent mask of the device isn't
suitable for accessing the direct DMA space and the device also happens
to have an active IOMMU table.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Michael Ellerman

powerpc/pci: add dma_set_mask to pci_controller_ops

2015-06-02T03:18:49+00:00

Some systems only need to deal with DMA masks for PCI devices.
For these systems, we can avoid the need for a platform hook and
instead use a pci controller based hook.

Signed-off-by: Daniel Axtens 
Signed-off-by: Michael Ellerman

powerpc: Only do dynamic DMA zone limits on platforms that need it

2014-10-16T22:21:44+00:00

Scott's patch 1c98025c6c95 "Dynamic DMA zone limits" changed
dma_direct_alloc_coherent() to start using dev->coherent_dma_mask.

That seems fair enough, but it exposes the fact that some of the drivers
we care about on IBM platforms aren't setting the coherent mask.

The proper fix is to have drivers set the coherent mask and also have
the platform code honor it.

For now, just restrict the dynamic DMA zone limits to the platforms that
need it.

Signed-off-by: Michael Ellerman 
Acked-by: Scott Wood

Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux.git

2014-10-03T22:59:06+00:00

Freescale updates from Scott (27 commits):

  "Highlights include DMA32 zone support (SATA, USB, etc now works on 64-bit
   FSL kernels), MSI changes, 8xx optimizations and cleanup, t104x board
   support, and PrPMC PCI enumeration."

powerpc/powernv: Override dma_get_required_mask()

2014-09-30T07:15:20+00:00

The dma_get_required_mask() function is used by some drivers to
query the platform about what DMA mask is needed to cover all of
memory. This is a bit of a strange semantic when we have to choose
between IOMMU translation or bypass, but essentially what it means
is "what DMA mask will give best performances".

Currently, our IOMMU backend always returns a 32-bit mask here, we
don't do anything special to it when we have bypass available. This
causes some drivers to choose a 32-bit mask, thus losing the ability
to use the bypass window, thinking this is more efficient. The problem
was reported from the driver of following device:

0004:03:00.0 0107: 1000:0087 (rev 05)
0004:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios \
             Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)

This patch adds an override of that function in order to, instead,
return a 64-bit mask whenever a bypass window is available in order
for drivers to prefer this configuration.

Reported-by: Murali N. Iyer 
Suggested-by: Benjamin Herrenschmidt 
Signed-off-by: Gavin Shan 
Signed-off-by: Michael Ellerman

powerpc/64: Honor swiotlb limit in coherent allocations

2014-09-03T22:58:22+00:00

FSL PCI cannot directly address the whole lower 4 GiB due to
conflicts with PCICSRBAR and outbound windows, and thus
max_direct_dma_addr is less than 4GiB.  Honor that limit in
dma_direct_alloc_coherent().

Note that setting the DMA mask to 31 bits is not an option, since many
PCI drivers would fail if we reject 32-bit DMA in dma_supported(), and
we have no control over the setting of coherent_dma_mask if
dma_supported() returns true.

Signed-off-by: Scott Wood 
Cc: Shaohui Xie

powerpc: Dynamic DMA zone limits

2014-09-03T22:58:21+00:00

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.

Signed-off-by: Scott Wood 
Cc: Shaohui Xie

powerpc/powernv: Add iommu DMA bypass support for IODA2

2014-02-11T05:07:37+00:00

This patch adds the support for to create a direct iommu "bypass"
window on IODA2 bridges (such as Power8) allowing to bypass iommu
page translation completely for 64-bit DMA capable devices, thus
significantly improving DMA performances.

Additionally, this adds a hook to the struct iommu_table so that
the IOMMU API / VFIO can disable the bypass when external ownership
is requested, since in that case, the device will be used by an
environment such as userspace or a KVM guest which must not be
allowed to bypass translations.

Signed-off-by: Benjamin Herrenschmidt

powerpc/kernel: Remove uses of abs_to_virt() and virt_to_abs()

2012-09-05T05:19:30+00:00

These days they are just __va() and __pa() respectively.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt