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  1. 25 7月, 2014 1 次提交
  3. 22 5月, 2014 2 次提交
  5. 06 3月, 2014 1 次提交
    • L
      dma: Remove comment about embedding dma_slave_config into custom structs · 7cbccb55
      由 Lars-Peter Clausen 提交于 
      The documentation for the dma_slave_config struct recommends that if a DMA
controller has special configuration options, which can not be configured
through the dma_slave_config struct, the driver should create its own custom
config struct and embed the dma_slave_config struct in it and pass the custom
config struct to dmaengine_slave_config(). This overloads the generic
dmaengine_slave_config() API with custom semantics and any caller of the
dmaengine_slave_config() that is not aware of these special semantics will cause
undefined behavior. This means that it is impossible for generic code to make
use of dmaengine_slave_config(). Such a restriction contradicts the very idea of
having a generic API.

E.g. consider the following case of a DMA controller that has an option to
reverse the field polarity of the DMA transfer with the following implementation
for setting the configuration:

	struct my_slave_config {
		struct dma_slave_config config;
		unsigned int field_polarity;
	};

	static int my_dma_controller_slave_config(struct dma_chan *chan,
		struct dma_slave_config *config)
	{
		struct my_slave_config *my_cfg = container_of(config,
				struct my_slave_config, config);

		...
		my_dma_set_field_polarity(chan, my_cfg->field_polarity);
		...
	}

Now a generic user of the dmaengine API might want to configure a DMA channel
for this DMA controller that it obtained using the following code:

	struct dma_slave_config config;

	config.src_addr = ...;
	...
	dmaengine_slave_config(chan, &config);

The call to dmaengine_slave_config() will eventually call into
my_dma_controller_slave_config() which will cast from dma_slave_config to
my_slave_config and then tries to access the field_polarity member. Since the
dma_slave_config struct that was passed in was never embedded into a
my_slave_config struct this attempt will just read random stack garbage and use
that to configure the DMA controller. This is bad. Instead, if a DMA controller
really needs to have custom configuration options, the driver should create a
custom API for it. This makes it very clear that there is a direct dependency
of a user of such an API and the implementer. E.g.:

	int my_dma_set_field_polarity(struct dma_chan *chan,
		unsigned int field_polarity) {
		if (chan->device->dev->driver != &my_dma_controller_driver.driver)
			return -EINVAL;
		...
	}
	EXPORT_SYMBOL_GPL(my_dma_set_field_polarity);
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      7cbccb55
  7. 20 1月, 2014 1 次提交
  9. 15 1月, 2014 1 次提交
    • L
      dma: Indicate residue granularity in dma_slave_caps · 50720563
      由 Lars-Peter Clausen 提交于 
      This patch adds a new field to the dma_slave_caps struct which indicates the
granularity with which the driver is able to update the residue field of the
dma_tx_state struct. Making this information available to dmaengine users allows
them to make better decisions on how to operate. E.g. for audio certain features
like wakeup less operation or timer based scheduling only make sense and work
correctly if the reported residue is fine-grained enough.

Right now four different levels of granularity are supported:
	* DESCRIPTOR: The DMA channel is only able to tell whether a descriptor has
	  been completed or not, which means residue reporting is not supported by
	  this channel. The residue field of the dma_tx_state field will always be
	  0.
	* SEGMENT: The DMA channel updates the residue field after each successfully
	  completed segment of the transfer (For cyclic transfers this is after each
	  period). This is typically implemented by having the hardware generate an
	  interrupt after each transferred segment and then the drivers updates the
	  outstanding residue by the size of the segment. Another possibility is if
	  the hardware supports SG and the segment descriptor has a field which gets
	  set after the segment has been completed. The driver then counts the
	  number of segments without the flag set to compute the residue.
	* BURST: The DMA channel updates the residue field after each transferred
	  burst. This is typically only supported if the hardware has a progress
	  register of some sort (E.g. a register with the current read/write address
	  or a register with the amount of bursts/beats/bytes that have been
	  transferred or still need to be transferred).
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Acked-by: NVinod Koul <vinod.koul@intel.com>
Signed-off-by: NMark Brown <broonie@linaro.org>
      50720563
  11. 18 12月, 2013 1 次提交
  13. 10 12月, 2013 2 次提交
    • S
      dma: add dma_get_any_slave_channel(), for use in of_xlate() · 8010dad5
      由 Stephen Warren 提交于 
      mmp_pdma.c implements a custom of_xlate() function that is 95% identical
to what Tegra will need. Create a function to implement the common part,
so everyone doesn't just cut/paste the implementation.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: dmaengine@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      8010dad5
    • S
      dma: add channel request API that supports deferred probe · 0ad7c000
      由 Stephen Warren 提交于 
      dma_request_slave_channel() simply returns NULL whenever DMA channel
lookup fails. Lookup could fail for two distinct reasons:

a) No DMA specification exists for the channel name.
   This includes situations where no DMA specifications exist at all, or
   other general lookup problems.

b) A DMA specification does exist, yet the driver for that channel is not
   yet registered.

Case (b) should trigger deferred probe in client drivers. However, since
they have no way to differentiate the two situations, it cannot.

Implement new function dma_request_slave_channel_reason(), which performs
identically to dma_request_slave_channel(), except that it returns an
error-pointer rather than NULL, which allows callers to detect when
deferred probe should occur.

Eventually, all drivers should be converted to this new API, the old API
removed, and the new API renamed to the more desirable name. This patch
doesn't convert the existing API and all drivers in one go, since some
drivers call dma_request_slave_channel() then dma_request_channel() if
that fails. That would require either modifying dma_request_channel() in
the same way, or adding extra error-handling code to all affected
drivers, and there are close to 100 drivers using the other API, rather
than just the 15-20 or so that use dma_request_slave_channel(), which
might be tenable in a single patch.

acpi_dma_request_slave_chan_by_name() doesn't currently implement
deferred probe. It should, but this will be addressed later.
Acked-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      0ad7c000
  15. 15 11月, 2013 2 次提交
  17. 14 11月, 2013 2 次提交
  19. 25 10月, 2013 2 次提交
  21. 10 9月, 2013 1 次提交
  23. 02 9月, 2013 1 次提交
  25. 23 8月, 2013 1 次提交
  27. 13 8月, 2013 1 次提交
    • Z
      dmaengine: add interface of dma_get_slave_channel · 7bb587f4
      由 Zhangfei Gao 提交于 
      Suggested by Arnd, add dma_get_slave_channel interface
Dma host driver could get specific channel specificied by request line, rather than filter.

host example:
static struct dma_chan *xx_of_dma_simple_xlate(struct of_phandle_args *dma_spec,
		struct of_dma *ofdma)
{
	struct xx_dma_dev *d = ofdma->of_dma_data;
	unsigned int request = dma_spec->args[0];

	if (request > d->dma_requests)
		return NULL;

	return dma_get_slave_channel(&(d->chans[request].vc.chan));
}

probe:
of_dma_controller_register((&op->dev)->of_node, xx_of_dma_simple_xlate, d);
Signed-off-by: NZhangfei Gao <zhangfei.gao@linaro.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      7bb587f4
  29. 16 7月, 2013 1 次提交
  31. 04 7月, 2013 1 次提交
  33. 15 4月, 2013 2 次提交
  35. 28 2月, 2013 1 次提交
  37. 14 2月, 2013 1 次提交
  39. 12 1月, 2013 1 次提交
  41. 08 1月, 2013 5 次提交
  43. 07 1月, 2013 2 次提交
  45. 25 9月, 2012 1 次提交
  47. 22 9月, 2012 1 次提交
  49. 20 6月, 2012 2 次提交
  51. 08 6月, 2012 1 次提交
  53. 01 6月, 2012 1 次提交
  55. 11 5月, 2012 1 次提交