linux.git/kernel/dma/mapping.c, branch v5.15-rc2

dma-mapping: fix the kerneldoc for dma_map_sg_attrs

2021-09-06T12:40:47+00:00

Add the missing description for the nents parameter, and fix a trivial
misalignment.

Fixes: fffe3cc8c219 ("dma-mapping: allow map_sg() ops to return negative error codes")
Reported-by: Stephen Rothwell 
Signed-off-by: Christoph Hellwig

dma-mapping: return an unsigned int from dma_map_sg{,_attrs}

2021-08-14T07:18:36+00:00

These can only return 0 for failure or the number of entries, so turn
the return value into an unsigned int.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Logan Gunthorpe

dma-mapping: disallow .map_sg operations from returning zero on error

2021-08-09T15:15:02+00:00

Now that all the .map_sg operations have been converted to returning
proper error codes, drop the code to handle a zero return value,
add a warning if a zero is returned.

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig

dma-mapping: allow map_sg() ops to return negative error codes

2021-08-09T15:13:02+00:00

Allow dma_map_sgtable() to pass errors from the map_sg() ops. This
will be required for returning appropriate error codes when mapping
P2PDMA memory.

Introduce __dma_map_sg_attrs() which will return the raw error code
from the map_sg operation (whether it be negative or zero). Then add a
dma_map_sg_attrs() wrapper to convert any negative errors to zero to
satisfy the existing calling convention.

dma_map_sgtable() defines three error codes that .map_sg implementations
are allowed to return: -EINVAL, -ENOMEM and -EIO. The latter of which
is a generic return for cases that are passing DMA_MAPPING_ERROR
through.

dma_map_sgtable() will convert a zero error return for old map_sg() ops
into a -EIO return and return any negative errors as reported.

This allows map_sg implementations to start returning multiple
negative error codes. Legacy map_sg implementations can continue
to return zero until they are all converted.

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Christoph Hellwig

dma-mapping: add a dma_alloc_noncontiguous API

2021-03-15T09:02:31+00:00

Add a new API that returns a potentiall virtually non-contigous sg_table
and a DMA address.  This API is only properly implemented for dma-iommu
and will simply return a contigious chunk as a fallback.

The intent is that drivers can use this API if either:

 - no kernel mapping or only temporary kernel mappings are required.
   That is as a better replacement for DMA_ATTR_NO_KERNEL_MAPPING
 - a kernel mapping is required for cached and DMA mapped pages, but
   the driver also needs the pages to e.g. map them to userspace.
   In that sense it is a replacement for some aspects of the recently
   removed and never fully implemented DMA_ATTR_NON_CONSISTENT

Signed-off-by: Christoph Hellwig 
Reviewed-by: Tomasz Figa 
Tested-by: Ricardo Ribalda

dma-mapping: refactor dma_{alloc,free}_pages

2021-03-15T09:02:31+00:00

Factour out internal versions without the dma_debug calls in preparation
for callers that will need different dma_debug calls.

Note that this changes the dma_debug calls to get the not page aligned
size values, but as long as alloc and free agree on one variant we are
fine.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Tomasz Figa 
Tested-by: Ricardo Ribalda

dma-mapping: add a dma_mmap_pages helper

2021-03-15T09:02:31+00:00

Add a helper to map memory allocated using dma_alloc_pages into
a user address space, similar to the dma_alloc_attrs function for
coherent allocations.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Tomasz Figa 
Tested-by: Ricardo Ribalda

Merge tag 'dma-mapping-5.12' of git://git.infradead.org/users/hch/dma-mapping

2021-02-24T17:54:24+00:00

Pull dma-mapping updates from Christoph Hellwig:

 - add support to emulate processing delays in the DMA API benchmark
   selftest (Barry Song)

 - remove support for non-contiguous noncoherent allocations, which
   aren't used and will be replaced by a different API

* tag 'dma-mapping-5.12' of git://git.infradead.org/users/hch/dma-mapping:
  dma-mapping: remove the {alloc,free}_noncoherent methods
  dma-mapping: benchmark: pretend DMA is transmitting

driver core: lift dma_default_coherent into common code

2021-02-13T08:51:45+00:00

Lift the dma_default_coherent variable from the mips architecture code
to the driver core.  This allows an architecture to sdefault all device
to be DMA coherent at run time, even if the kernel is build with support
for DMA noncoherent device.  By allowing device_initialize to set the
->dma_coherent field to this default the amount of arch hooks required
for this behavior can be greatly reduced.

Signed-off-by: Christoph Hellwig 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Thomas Bogendoerfer

dma-mapping: remove the {alloc,free}_noncoherent methods

2021-02-09T17:01:38+00:00

It turns out allowing non-contigous allocations here was a rather bad
idea, as we'll now need to define ways to get the pages for mmaping
or dma_buf sharing.  Revert this change and stick to the original
concept.  A different API for the use case of non-contigous allocations
will be added back later.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Tomasz Figa 
Tested-by: Ricardo Ribalda :wq