Commit Graph

15 Commits

Author SHA1 Message Date
Vinod Koul
d3f1e93ce8 Merge branch 'topic/async' into for-linus 2016-01-06 15:17:47 +05:30
Peter Ujfalusi
a8135d0d79 dmaengine: core: Introduce new, universal API to request a channel
The two API function can cover most, if not all current APIs used to
request a channel. With minimal effort dmaengine drivers, platforms and
dmaengine user drivers can be converted to use the two function.

struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);

To request any channel matching with the requested capabilities, can be
used to request channel for memcpy, memset, xor, etc where no hardware
synchronization is needed.

struct dma_chan *dma_request_chan(struct device *dev, const char *name);
To request a slave channel. The dma_request_chan() will try to find the
channel via DT, ACPI or in case if the kernel booted in non DT/ACPI mode
it will use a filter lookup table and retrieves the needed information from
the dma_slave_map provided by the DMA drivers.
This legacy mode needs changes in platform code, in dmaengine drivers and
finally the dmaengine user drivers can be converted:

For each dmaengine driver an array of DMA device, slave and the parameter
for the filter function needs to be added:

static const struct dma_slave_map da830_edma_map[] = {
	{ "davinci-mcasp.0", "rx", EDMA_FILTER_PARAM(0, 0) },
	{ "davinci-mcasp.0", "tx", EDMA_FILTER_PARAM(0, 1) },
	{ "davinci-mcasp.1", "rx", EDMA_FILTER_PARAM(0, 2) },
	{ "davinci-mcasp.1", "tx", EDMA_FILTER_PARAM(0, 3) },
	{ "davinci-mcasp.2", "rx", EDMA_FILTER_PARAM(0, 4) },
	{ "davinci-mcasp.2", "tx", EDMA_FILTER_PARAM(0, 5) },
	{ "spi_davinci.0", "rx", EDMA_FILTER_PARAM(0, 14) },
	{ "spi_davinci.0", "tx", EDMA_FILTER_PARAM(0, 15) },
	{ "da830-mmc.0", "rx", EDMA_FILTER_PARAM(0, 16) },
	{ "da830-mmc.0", "tx", EDMA_FILTER_PARAM(0, 17) },
	{ "spi_davinci.1", "rx", EDMA_FILTER_PARAM(0, 18) },
	{ "spi_davinci.1", "tx", EDMA_FILTER_PARAM(0, 19) },
};

This information is going to be needed by the dmaengine driver, so
modification to the platform_data is needed, and the driver map should be
added to the pdata of the DMA driver:

da8xx_edma0_pdata.slave_map = da830_edma_map;
da8xx_edma0_pdata.slavecnt = ARRAY_SIZE(da830_edma_map);

The DMA driver then needs to configure the needed device -> filter_fn
mapping before it registers with dma_async_device_register() :

ecc->dma_slave.filter_map.map = info->slave_map;
ecc->dma_slave.filter_map.mapcnt = info->slavecnt;
ecc->dma_slave.filter_map.fn = edma_filter_fn;

When neither DT or ACPI lookup is available the dma_request_chan() will
try to match the requester's device name with the filter_map's list of
device names, when a match found it will use the information from the
dma_slave_map to get the channel with the dma_get_channel() internal
function.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2015-12-18 11:17:26 +05:30
Lars-Peter Clausen
b36f09c3c4 dmaengine: Add transfer termination synchronization support
The DMAengine API has a long standing race condition that is inherent to
the API itself. Calling dmaengine_terminate_all() is supposed to stop and
abort any pending or active transfers that have previously been submitted.
Unfortunately it is possible that this operation races against a currently
running (or with some drivers also scheduled) completion callback.

Since the API allows dmaengine_terminate_all() to be called from atomic
context as well as from within a completion callback it is not possible to
synchronize to the execution of the completion callback from within
dmaengine_terminate_all() itself.

This means that a user of the DMAengine API does not know when it is safe
to free resources used in the completion callback, which can result in a
use-after-free race condition.

This patch addresses the issue by introducing an explicit synchronization
primitive to the DMAengine API called dmaengine_synchronize().

The existing dmaengine_terminate_all() is deprecated in favor of
dmaengine_terminate_sync() and dmaengine_terminate_async(). The former
aborts all pending and active transfers and synchronizes to the current
context, meaning it will wait until all running completion callbacks have
finished. This means it is only possible to call this function from
non-atomic context. The later function does not synchronize, but can still
be used in atomic context or from within a complete callback. It has to be
followed up by dmaengine_synchronize() before a client can free the
resources used in a completion callback.

In addition to this the semantics of the device_terminate_all() callback
are slightly relaxed by this patch. It is now OK for a driver to only
schedule the termination of the active transfer, but does not necessarily
have to wait until the DMA controller has completely stopped. The driver
must ensure though that the controller has stopped and no longer accesses
any memory when the device_synchronize() callback returns.

This was in part done since most drivers do not pay attention to this
anyway at the moment and to emphasize that this needs to be done when the
device_synchronize() callback is implemented. But it also helps with
implementing support for devices where stopping the controller can require
operations that may sleep.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2015-11-16 08:28:52 +05:30
Vinod Koul
60884ddecd Documentation: dmaengine: Add DMA_CTRL_REUSE documentation
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Acked-by:Robert Jarzmik <robert.jarzmik@free.fr>
2015-08-17 13:46:22 +05:30
Vinod Koul
06f10e2f93 Documentation: dmaengine: fix the DMA_CTRL_ACK documentation
As discussed recently the meaning of DMA_CTRL_ACK is that a desc cannot be
reused by provider until the client acknowledges receipt, i.e. has has a
chance to establish any dependency chains. So update documentation

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Acked-by:Robert Jarzmik <robert.jarzmik@free.fr>
2015-08-17 13:46:22 +05:30
Vinod Koul
f2704052cb Merge branch 'topic/pxa' into for-linus 2015-06-25 09:21:58 +05:30
Robert Jarzmik
5f88d9706f Documentation: dmaengine: document DMA_CTRL_ACK
Add documentation about acking the transfers, and their
reusability.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2015-06-17 22:16:15 +05:30
Robert Jarzmik
16eea6b487 Documentation: dmaengine: pxa-dma design
Document the new design of the pxa dma driver.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2015-05-26 09:18:28 +05:30
Linus Torvalds
ce1d3fde87 Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma
Pull dmaengine updates from Vinod Koul:
 "This update brings:

   - the big cleanup up by Maxime for device control and slave
     capabilities.  This makes the API much cleaner.

   - new IMG MDC driver by Andrew

   - new Renesas R-Car Gen2 DMA Controller driver by Laurent along with
     bunch of fixes on rcar drivers

   - odd fixes and updates spread over driver"

* 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma: (130 commits)
  dmaengine: pl330: add DMA_PAUSE feature
  dmaengine: pl330: improve pl330_tx_status() function
  dmaengine: rcar-dmac: Disable channel 0 when using IOMMU
  dmaengine: rcar-dmac: Work around descriptor mode IOMMU errata
  dmaengine: rcar-dmac: Allocate hardware descriptors with DMAC device
  dmaengine: rcar-dmac: Fix oops due to unintialized list in error ISR
  dmaengine: rcar-dmac: Fix spinlock issues in interrupt
  dmaenegine: edma: fix sparse warnings
  dmaengine: rcar-dmac: Fix uninitialized variable usage
  dmaengine: shdmac: extend PM methods
  dmaengine: shdmac: use SET_RUNTIME_PM_OPS()
  dmaengine: pl330: fix bug that cause start the same descs in cyclic
  dmaengine: at_xdmac: allow muliple dwidths when doing slave transfers
  dmaengine: at_xdmac: simplify channel configuration stuff
  dmaengine: at_xdmac: introduce save_cc field
  dmaengine: at_xdmac: wait for in-progress transaction to complete after pausing a channel
  ioat: fail self-test if wait_for_completion times out
  dmaengine: dw: define DW_DMA_MAX_NR_MASTERS
  dmaengine: dw: amend description of dma_dev field
  dmatest: move src_off, dst_off, len inside loop
  ...
2015-02-18 08:49:20 -08:00
Henrik Austad
912ee9ca37 Update of Documentation/dmaengine/00-INDEX
- client.txt was moved by f36d2e67 (dmaengine: Move the current doc to a
  folder of its own)
- dmatmest.txt was moved by 935cdb56 (dmanegine: move dmatest.txt to
  dmaengine folder)
- provider.txt was added by c4d2ae967 (Documentation: dmaengine: Add a
  documentation for the dma controller API).

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: dmaengine@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2014-12-29 15:28:24 -07:00
Vinod Koul
6269591b98 Documentation: dmaengine: clarify dma_slave_config expectations
dma_slave_config is expected to be set for slave operations Only, not for
memcpy ones

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2014-12-22 12:34:22 +05:30
Maxime Ripard
1faab1f2e3 Documentation: dmaengine: Update the documentation
Now that we have splitted device_control and removed device_slave_caps in favor
of a few dma_device variables, update the documentation accordingly.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2014-12-22 12:34:22 +05:30
Vinod Koul
935cdb5634 Documentation: dmanegine: move dmatest.txt to dmaengine folder
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2014-11-06 11:17:37 +05:30
Maxime Ripard
c4d2ae967c Documentation: dmaengine: Add a documentation for the dma controller API
The dmaengine is neither trivial nor properly documented at the moment, which
means a lot of trial and error development, which is not that good for such a
central piece of the system.

Attempt at making such a documentation.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
[fixed some minor typos]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2014-11-06 11:15:58 +05:30
Maxime Ripard
f36d2e6752 Documentation: dmaengine: Move the current doc to a folder of its own
Move the current client-side documentation to a subfolder to prepare the
introduction of a provider-side API documentation.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
2014-11-06 11:15:51 +05:30