DMA engines used with displays perform 2D interleaved transfers to read
framebuffers from memory and feed the data to the display engine. As the
same framebuffer can be displayed for multiple frames, the DMA
transactions need to be repeated until a new framebuffer replaces the
current one. This feature is implemented natively by some DMA engines
that have the ability to repeat transactions and switch to a new
transaction at the end of a transfer without any race condition or frame
loss.
This patch implements support for this feature in the DMA engine API. A
new DMA_PREP_REPEAT transaction flag allows DMA clients to instruct the
DMA channel to repeat the transaction automatically until one or more
new transactions are issued on the channel (or until all active DMA
transfers are explicitly terminated with the dmaengine_terminate_*()
functions). A new DMA_REPEAT transaction type is also added for DMA
engine drivers to report their support of the DMA_PREP_REPEAT flag.
A new DMA_PREP_LOAD_EOT transaction flag is also introduced (with a
corresponding DMA_LOAD_EOT capability bit), as requested during the
review of v4. The flag instructs the DMA channel that the transaction
being queued should replace the active repeated transaction when the
latter terminates (at End Of Transaction). Not setting the flag will
result in the active repeated transaction to continue being repeated,
and the new transaction being silently ignored.
The DMA_PREP_REPEAT flag is currently supported for interleaved
transactions only. Its usage can easily be extended to cover more
transaction types simply by adding an appropriate check in the
corresponding dmaengine_prep_*() function.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200717013337.24122-3-laurent.pinchart@ideasonboard.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Pull documentation updates from Jonathan Corbet:
"This has been a busy cycle for documentation work.
Highlights include:
- Lots of RST conversion work by Mauro, Daniel ALmeida, and others.
Maybe someday we'll get to the end of this stuff...maybe...
- Some organizational work to bring some order to the core-api
manual.
- Various new docs and additions to the existing documentation.
- Typo fixes, warning fixes, ..."
* tag 'docs-5.7' of git://git.lwn.net/linux: (123 commits)
Documentation: x86: exception-tables: document CONFIG_BUILDTIME_TABLE_SORT
MAINTAINERS: adjust to filesystem doc ReST conversion
docs: deprecated.rst: Add BUG()-family
doc: zh_CN: add translation for virtiofs
doc: zh_CN: index files in filesystems subdirectory
docs: locking: Drop :c:func: throughout
docs: locking: Add 'need' to hardirq section
docs: conf.py: avoid thousands of duplicate label warning on Sphinx
docs: prevent warnings due to autosectionlabel
docs: fix reference to core-api/namespaces.rst
docs: fix pointers to io-mapping.rst and io_ordering.rst files
Documentation: Better document the softlockup_panic sysctl
docs: hw-vuln: tsx_async_abort.rst: get rid of an unused ref
docs: perf: imx-ddr.rst: get rid of a warning
docs: filesystems: fuse.rst: supress a Sphinx warning
docs: translations: it: avoid duplicate refs at programming-language.rst
docs: driver.rst: supress two ReSt warnings
docs: trace: events.rst: convert some new stuff to ReST format
Documentation: Add io_ordering.rst to driver-api manual
Documentation: Add io-mapping.rst to driver-api manual
...
Changeset 58ad30cf91 ("docs: fix reference to core-api/namespaces.rst")
enabled a new feature at Sphinx: it will now generate index for each
document title, plus to each chapter inside it.
There's a drawback, though: one document cannot have two sections
with the same name anymore.
A followup patch will change the logic of autosectionlabel to
avoid most creating references for every single section title,
but still we need to be able to reference the chapters inside
a document.
There are a few places where there are two chapters with the
same name. This patch renames one of the chapters, in order to
avoid symbol conflict within the same document.
PS.: as I don't speach Chinese, I had some help from a friend
(Wen Liu) at the Chinese translation for "publishing patches"
for this document:
Documentation/translations/zh_CN/process/5.Posting.rst
Fixes: 58ad30cf91 ("docs: fix reference to core-api/namespaces.rst")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2bffb91e4a63d41bf5fae1c23e1e8b3bba0b8806.1584716446.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Get rid of those warnings by adding extra blank lines:
Documentation/driver-api/dmaengine/provider.rst:270: WARNING: Unexpected indentation.
Documentation/driver-api/dmaengine/provider.rst:273: WARNING: Block quote ends without a blank line; unexpected unindent.
Documentation/driver-api/dmaengine/provider.rst:288: WARNING: Unexpected indentation.
Documentation/driver-api/dmaengine/provider.rst:290: WARNING: Block quote ends without a blank line; unexpected unindent.
While here, use parenthesis after get_metadata_ptr/set_metadata_len,
as, if some day someone adds a kerneldoc markup for those, it
should automatically generate a cross-reference to them.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/62cf2a87b379a92c9c0e5a40c2ae8a138b01fe0a.1583250595.git.mchehab+huawei@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The newly added metadata documentation title was not properly indented
resulting in doc build break:
Sphinx parallel build error:
docutils.utils.SystemMessage: /linux/Documentation/driver-api/dmaengine/client.rst:155: (SEVERE/4) Unexpected section title.
Optional: per descriptor metadata
---------------------------------
Fix this by doing the right indent
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Fixes: 7d083ae983 ("dmaengine: doc: Add sections for per descriptor metadata support")
Link: https://lore.kernel.org/r/20200128125032.1650816-1-vkoul@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The genindex logic is meant to be used only for html output, as
pdf build has its own way to generate indexes.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org> # dmaengine and soundwire
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix the formatting of the multi-channel test usage example. Call out
the note about parameter ordering and add detail on the settings of
parameters for the new version of dmatest.
Fixes: f80f9988a2 ("dmaengine: Documentation: Add documentation for multi chan testing")
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
It clarifies that the DMA description pointer returned by
`dmaengine_prep_*` function should not be used after submission.
Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Fix markup warning: insert a blank line before the hint.
Documentation/driver-api/dmaengine/dmatest.rst:63: WARNING: Unexpected indentation.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Pull dmaengine updates from Vinod Koul:
"This includes a new driver, removes R-Mobile APE6 as it is no longer
used, sprd cyclic dma support, last batch of dma_slave_config
direction removal and random updates to bunch of drivers.
Summary:
- New driver for UniPhier MIO DMA controller
- Remove R-Mobile APE6 support
- Sprd driver updates and support for cyclic link-list
- Remove dma_slave_config direction usage from rest of drivers
- Minor updates to dmatest, dw-dmac, zynqmp and bcm dma drivers"
* tag 'dmaengine-4.21-rc1' of git://git.infradead.org/users/vkoul/slave-dma: (48 commits)
dmaengine: qcom_hidma: convert to DEFINE_SHOW_ATTRIBUTE
dmaengine: pxa: remove DBGFS_FUNC_DECL()
dmaengine: mic_x100_dma: convert to DEFINE_SHOW_ATTRIBUTE
dmaengine: amba-pl08x: convert to DEFINE_SHOW_ATTRIBUTE
dmaengine: Documentation: Add documentation for multi chan testing
dmaengine: dmatest: Add transfer_size parameter
dmaengine: dmatest: Add alignment parameter
dmaengine: dmatest: Use fixed point div to calculate iops
dmaengine: dmatest: Add support for multi channel testing
dmaengine: rcar-dmac: Document R8A774C0 bindings
dt-bindings: dmaengine: usb-dmac: Add binding for r8a774c0
dmaengine: zynqmp_dma: replace spin_lock_bh with spin_lock_irqsave
dmaengine: sprd: Add me as one of the module authors
dmaengine: sprd: Support DMA 2-stage transfer mode
dmaengine: sprd: Support DMA link-list cyclic callback
dmaengine: sprd: Set cur_desc as NULL when free or terminate one dma channel
dmaengine: sprd: Fix the last link-list configuration
dmaengine: sprd: Get transfer residue depending on the transfer direction
dmaengine: sprd: Remove direction usage from struct dma_slave_config
dmaengine: dmatest: fix a small memory leak in dmatest_func()
...
It's not the first time I've got a private email in regard to
dmatest.c module.
Motivate people, by adding a note, to send their questions
to the mailing list instead
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Fix spelling for parenthesis in dmatest documentation.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[ jc: did s/parenthesis/parentheses/ and reflowed ]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Make dmatest.rst indeed reST compatible.
Achieve this by fixing several formatting issues.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The documentation is not so clear for newbies in a sense of what type of the
channels are supported by it.
Clarify this by adding a note at the preamble of the documentation.
Reported-by: "Zhu, Tony" <tony.zhu@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-By: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Pull dmaengine updates from Vinod Koul:
"This time is smallish update with updates mainly to drivers:
- updates to xilinx and zynqmp dma controllers
- update reside calculation for rcar controller
- more RSTify fixes for documentation
- add support for race free transfer termination and updating for
users for that
- support for new rev of hidma with addition new APIs to get device
match data in ACPI/OF
- random updates to bunch of other drivers"
* tag 'dmaengine-4.16-rc1' of git://git.infradead.org/users/vkoul/slave-dma: (47 commits)
dmaengine: dmatest: fix container_of member in dmatest_callback
dmaengine: stm32-dmamux: Remove unnecessary platform_get_resource() error check
dmaengine: sprd: statify 'sprd_dma_prep_dma_memcpy'
dmaengine: qcom_hidma: simplify DT resource parsing
dmaengine: xilinx_dma: Free BD consistent memory
dmaengine: xilinx_dma: Fix warning variable prev set but not used
dmaengine: xilinx_dma: properly configure the SG mode bit in the driver for cdma
dmaengine: doc: format struct fields using monospace
dmaengine: doc: fix bullet list formatting
dmaengine: ti-dma-crossbar: Fix event mapping for TPCC_EVT_MUX_60_63
dmaengine: cppi41: Fix channel queues array size check
dmaengine: imx-sdma: Add MODULE_FIRMWARE
dmaengine: xilinx_dma: Fix typos
dmaengine: xilinx_dma: Differentiate probe based on the ip type
dmaengine: xilinx_dma: fix style issues from checkpatch
dmaengine: xilinx_dma: Fix kernel doc warnings
dmaengine: xilinx_dma: Fix race condition in the driver for multiple descriptor scenario
dmaeninge: xilinx_dma: Fix bug in multiple frame stores scenario in vdma
dmaengine: xilinx_dma: Check for channel idle state before submitting dma descriptor
dmaengine: zynqmp_dma: Fix race condition in the probe
...
Monospace is more readable and is also used elsewhere in the docs.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
The bullet list documenting the 'struct dma_device' fields has several
nesting errors, making it render improperly. It also has incoherent
formatting: some fields have a description in the same bullet, some in
a sub-bullet.
Fix both to have a correct and coherent formatting.
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This patch fix following warning during 'make xmldocs'
Documentation/driver-api/dmaengine/client.rst:188:
WARNING: Title underline too short.
Further APIs:
------------
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This converts and moves pxa_dma file with some format
changes for RST style
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This converts and moves dmatest file with some format
changes for RST style
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This converts and moves client API file with some format
changes for RST style
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This moves and converts provider file with some format changes
for RST style
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This removes the index file and adds the index.rst as placeholder
and update driver-api index to add dmaengine. As a consequence
dmaengine documentation will be in driver-api/
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
