A very tiny temporal window exists in the residue calculation where :
- upon entering residue calculation, the transfer is ongoing
- when reading the current transfer pointer, it just changed to
the "finisher/linker" descriptor
In this case, the residue returned is the whole transfer length instead
of 0. Fix it.
This appears almost in one extreme case, where the driver is used
by older clients which inquire for residue in interrupt context, such
as the smsc91x ethernet driver, in a tight loop :
interrupt_handler()
dmaengine_submit()
do {
dmaengine_tx_status()
} while (residue > 0 || status != DMA_ERROR)
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
A very small number of devices don't use the flow control offered by
requestor lines. In these specific cases, the pxa dma driver should be
aware of that and not try to use a requestor line.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Since the commit to have an allocated list of virtual descriptors was
reverted, the pxa_dma driver is broken, as it assumes the descriptor is
placed on the allocated list upon allocation.
Fix the issue in pxa_dma by making an allocated virtual descriptor a
singleton.
Fixes: 8c8fe97b2b ("Revert "dmaengine: virt-dma: don't always free descriptor upon completion"")
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This fixes the following error:
drivers/dma/pxa_dma.c: In function ‘dbg_show_requester_chan’:
drivers/dma/pxa_dma.c:192:2: error: void value not ignored as it ought to be
pos += seq_printf(s, "DMA channel %d requester :\n", phy->idx);
^
drivers/dma/pxa_dma.c:197:8: error: void value not ignored as it ought to be
!!(drcmr & DRCMR_MAPVLD));
^
scripts/Makefile.build:258: recipe for target 'drivers/dma/pxa_dma.o' failed
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Don't use the direction passed in the configuration, and rely on each
transfer's direction to prepare the transfers. This will enable
future removal of direction parameter from dma_slave_config.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
In order to achieve smooth transition of pxa drivers from old legacy dma
handling to new dmaengine, introduce a function to "hide" dma physical
channels from dmaengine.
This is temporary situation where pxa dma will be handled in 2 places :
- arch/arm/plat-pxa/dma.c
- drivers/dma/pxa_dma.c
The resources, ie. dma channels, will be controlled by pxa_dma. The
legacy code will request or release a channel with
pxad_toggle_reserved_channel().
This is not very pretty, but it ensures both legacy and dmaengine
consumers can live in the same kernel until the conversion is done.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Reuse the debugging features which were available in pxa architecture.
This is a copy of the code from arch/arm/plat-pxa/dma, which is doomed
to disappear once the conversion is completed towards dmaengine.
This is a transfer of the commit "[ARM] pxa/dma: add debugfs
entries" (d294948c2c).
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This is a new driver for pxa SoCs, which is also compatible with the former
mmp_pdma.
The rationale behind a new driver (as opposed to incremental patching) was :
- the new driver relies on virt-dma, which obsoletes all the internal
structures of mmp_pdma (sw_desc, hw_desc, ...), and by consequence all the
functions
- mmp_pdma allocates dma coherent descriptors containing not only hardware
descriptors but linked list information
The new driver only puts the dma hardware descriptors (ie. 4 u32) into the
dma pool allocated memory. This changes completely the way descriptors are
handled
- the architecture behind the interrupt/tasklet management was rewritten to be
more conforming to virt-dma
- the buffers alignment is handled differently
The former driver assumed that the DMA channel stopped between each
descriptor. The new one chains descriptors to let the channel running. This
is a necessary guarantee for real-time high bandwidth usecases such as video
capture on "old" architectures such as pxa.
- hot chaining / cold chaining / no chaining
Whenever possible, submitting a descriptor "hot chains" it to a running
channel. There is still no guarantee that the descriptor will be issued, as
the channel might be stopped just before the descriptor is submitted. Yet
this allows to submit several video buffers, and resubmit a buffer while
another is under handling.
As before, dma_async_issue_pending() is the only guarantee to have all the
buffers issued.
When an alignment issue is detected (ie. one address in a descriptor is not
a multiple of 8), if the already running channel is in "aligned mode", the
channel will stop, and restarted in "misaligned mode" to finished the issued
list.
- descriptors reusing
A submitted, issued and completed descriptor can be reused, ie resubmitted if
it was prepared with the proper flag (DMA_PREP_ACK). Only a channel
resources release will in this case release that buffer.
This allows a rolling ring of buffers to be reused, where there are several
thousands of hardware descriptors used (video buffer for example).
Additionally, a set of more casual features is introduced :
- debugging traces
- lockless way to know if a descriptor is terminated or not
The driver was tested on zylonite board (pxa3xx) and mioa701 (pxa27x),
with dmatest, pxa_camera and pxamci.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
