Commit Graph

102 Commits

Author SHA1 Message Date
Akinobu Mita 812613591c spi: omap2-mcspi: poll OMAP2_MCSPI_CHSTAT_RXS for PIO transfer
When running the spi-loopback-test with slower clock rate like 10 KHz,
the test for 251 bytes transfer was failed.  This failure triggered an
spi-omap2-mcspi's error message "DMA RX last word empty".

This message means that PIO for reading the remaining bytes due to the
DMA transfer length reduction is failed.  This problem can be fixed by
polling OMAP2_MCSPI_CHSTAT_RXS bit in channel status register to wait
until the receive buffer register is filled.

Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2017-03-24 18:50:23 +00:00
Wei Yongjun 2e9c079ccc spi: omap2-mcspi: Remove redundant return value check of platform_get_resource()
Remove unneeded error handling on the result of a call
to platform_get_resource() when the value is passed to
devm_ioremap_resource().

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-10-24 16:08:30 +01:00
Vikram N af9e53fef7 spi: omap2-mcspi: Fix modifying platform resource data
currently during probe the resource data gets modified and device
physical address remains valid only during first load. If the module is
unloaded and loaded again, the ioremp will be done on a incorrect address
as the resource was modified during previous module load.
This patch fixes this issue.

Signed-off-by: Vikram N <vicky773@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-10-21 12:09:51 +01:00
Franklin S Cooper Jr 0ba1870f88 spi: omap2-mcspi: Use the SPI framework to handle DMA mapping
Currently, the driver handles mapping buffers to be used by the DMA.
However, there are times that the current mapping implementation will
fail for certain buffers. Fortunately, the SPI framework can detect
and map buffers so its usable by the DMA.

Update the driver to utilize the SPI framework for buffer
mapping instead. Also incorporate hooks that the framework uses to
determine if the DMA can or can not be used.

This will result in the original omap2_mcspi_transfer_one function being
deleted and omap2_mcspi_work_one being renamed to
omap2_mcspi_transfer_one. Previously transfer_one was only responsible
for mapping and work_one handled the transfer. But now only transferring
needs to be handled by the driver.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-07-08 10:48:02 +02:00
Franklin S Cooper Jr 4bd00413cd spi: omap2-mcspi: Add comments for RX only DMA buffer workaround
OMAP35x and OMAP37x mentions in the McSPI End-of-Transfer Sequences section
that if the McSPI is configured as a Master and only DMA RX is being
performed then the DMA transfer size needs to be reduced by 1 or 2.

This was originally implemented by:
commit 57c5c28dbc ("spi: omap2_mcspi rxdma bugfix")

This patch adds comments to clarify what is going on in the code since its
not obvious what problem its addressing.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-07-05 16:48:25 +02:00
Peter Ujfalusi b085c6129a spi: omap2-mcspi: Use dma_request_chan() for requesting DMA channel
With the new dma_request_chan() the client driver does not need to look for
the DMA resource and it does not need to pass filter_fn anymore.
By switching to the new API the driver can now support deferred probing
against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-04-29 18:15:48 +01:00
Tony Lindgren 0e6f357a5d spi: omap2-mcspi: Fix PM regression with deferred probe for pm_runtime_reinit
Commit 5de85b9d57 ("PM / runtime: Re-init runtime PM states at probe
error and driver unbind") introduced pm_runtime_reinit() that is used
to reinitialize PM runtime after -EPROBE_DEFER. This allows shutting
down the device after a failed probe.

However, for drivers using pm_runtime_use_autosuspend() this can cause
a state where suspend callback is never called after -EPROBE_DEFER.
On the following device driver probe, hardware state is different from
the PM runtime state causing omap_device to produce the following
error:

omap_device_enable() called from invalid state 1

And with omap_device and omap hardware being picky for PM, this will
block any deeper idle states in hardware.

The solution is to fix the drivers to follow the PM runtime documentation:

1. For sections of code that needs the device disabled, use
   pm_runtime_put_sync_suspend() if pm_runtime_set_autosuspend() has
   been set.

2. For driver exit code, use pm_runtime_dont_use_autosuspend() before
   pm_runtime_put_sync() if pm_runtime_use_autosuspend() has been
   set.

Fixes: 5de85b9d57 ("PM / runtime: Re-init runtime PM states at probe
error and driver unbind")
Cc: linux-spi@vger.kernel.org
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Nishanth Menon <nm@ti.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-02-12 22:33:09 +00:00
Michael Welling 2f538c017e spi: omap2-mcspi: Prevent duplicate gpio_request
Occasionally the setup function will be called multiple times. Only request
the gpio the first time otherwise -EBUSY will occur on subsequent calls to
setup.

Reported-by: Joseph Bell <joe@iachieved.it>

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-12-01 17:05:34 +00:00
Pascal Huerst beca365565 spi: omap2-mcspi: Add calls for pinctrl state select
This adds calls to pinctrl subsystem in order to switch pin states
on suspend/resume if you provide a "sleep" state in DT.

If no "sleep" state is provided in DT, these calls turn
to NOPs.

Signed-off-by: Pascal Huerst <pascal.huerst@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-11-19 17:48:52 +00:00
Neil Armstrong 468a32082b spi: omap2-mcspi: disable other channels CHCONF_FORCE in prepare_message
Since the "Switch driver to use transfer_one" change, the cs_change
behavior has changed and a channel chip select can still be
asserted when changing channel from a previous last transfer in a
message having the cs_change attribute.

Since there is no sense having multiple chip select being asserted at the
same time, disable all the remaining forced chip selects in a the
prepare_message called right before a spi_transfer_one_message call.
It ignores the current channel configuration in order to keep the
possibility to leave the chip select asserted between messages.

It fixes this bug on a DM8168 SoC ES2.1 Soc and an OMAP4 ES2.1 SoC.
It was hanging all the other channels transfers when a CHCONF_FORCE
is present on the wrong channel.

Fixes: b28cb9414d ("spi: omap2-mcspi: Switch driver to use transfer_one")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-10-22 15:26:22 +01:00
Sebastian Reichel 5f74db105b spi: omap2-mcspi: add runtime PM to set_cs()
Since commit ddcad7e906 omap2_mcspi_set_cs() is called without
runtime power management requested.  This patch fixes the problem by
requesting runtime power management in omap2_mcspi_set_cs().

Reported-By: Pali Rohár <pali.rohar@gmail.com>
Fixes: ddcad7e906 (spi: omap2-mcspi: Fix native cs with new set_cs)
Tested-By: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-07-24 17:40:40 +01:00
Michael Welling c4339ac775 spi: omap2-mcspi: Handle error on gpio_request
If a valid GPIO is specified but cannot be requested by the driver, print a
message and error out of omap2_mcspi_setup.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-25 13:00:04 +01:00
Michael Welling a06b430fd8 spi: omap2-mcspi: Fix GPIO chip select support
The OMAP2_MCSPI_CHCONF_FORCE must be toggled even when using GPIO
chip selects. This patch conditionally calls the omap2_mcspi_set_cs
function to do so when using GPIO chip selects.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-25 13:00:04 +01:00
Michael Welling 4373f8b6da spi: omap2-mcspi: Fix set_cs function for active high
The core spi driver swaps the polarity of the enable based on SPI_CS_HIGH.
The omap2 controller has an internal configuration register bit called
OMAP2_MCSPI_CHCONF_EPOL to handle active high chip selects as well.

So we have to revert swap the polarity back for the correct setting of the
OMAP2_MCSPI_CHCONF_FORCE bit in omap2_mcspi_set_cs.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-25 13:00:04 +01:00
Michael Welling be632f6584 spi: omap2-mcspi: Remove unnecessary delay
The core spi driver handles the delay between transactions.
This is a remanant from the transfer_one conversion.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-25 13:00:04 +01:00
Michael Welling ddcad7e906 spi: omap2-mcspi: Fix native cs with new set_cs
GPIO chip select patch series appears to have broken the native chip select
support. This patch pulls the manual native chip select toggling out of
the transfer_one routine and adds a set_cs routine.

Tested natively on AM3354 with SPI serial flash on spi0cs0.

Reported-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Michael Welling <mwelling@ieee.org>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-12 20:17:52 +01:00
Michael Welling bc7f9bbc80 spi: omap2-mcspi: Add gpio_request and init CS
If GPIO chip select is specified, request the GPIO in the setup function
and release it in the cleanup function.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-08 19:55:04 +01:00
Michael Welling b28cb9414d spi: omap2-mcspi: Switch driver to use transfer_one
Switches from transfer_one_message to transfer_one to prepare driver for
use of GPIO chip selects.

Signed-off-by: Michael Welling <mwelling@ieee.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-05-08 12:48:42 +01:00
Fionn Cleary c5a06e75f3 spi/omap2-mcpsi: Always call spi_finalize_current_message()
The spi queue waits forever for spi_finalize_current_message() to be
called, blocking the bus.  Ensure that all error paths from
omap2_mcspi_transfer_one_message() call spi_finalize_current_message().

Signed-off-by: Fionn Cleary <fionn.cleary@streamunlimited.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2015-04-24 10:55:24 +01:00
Jarkko Nikula 2c658e212c spi: Remove FSF mailing addresses
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2014-12-22 15:32:42 +00:00
Wolfram Sang 14ac00e033 spi: drop owner assignment from platform_drivers
A platform_driver does not need to set an owner, it will be populated by the
driver core.

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2014-10-20 16:21:36 +02:00
Jorge A. Ventura 3d0763c006 spi/omap-mcspi: Fix the spi task hangs waiting dma_rx
The spi hangs waiting the completion of omap2_mcspi_rx_callback.

Signed-off-by: Jorge A. Ventura <jorge.araujo.ventura@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org
2014-08-11 19:55:51 +01:00
Mark A. Greer 97ca0d6cc1 spi: omap2-mcspi: Configure hardware when slave driver changes mode
Commit id 2bd16e3e23
(spi: omap2-mcspi: Do not configure the controller
on each transfer unless needed) does its job too
well so omap2_mcspi_setup_transfer() isn't called
even when an SPI slave driver changes 'spi->mode'.
The result is that the mode requested by the SPI
slave driver never takes effect.

Fix this by adding the 'mode' member to the
omap2_mcspi_cs structure which holds the mode
value that the hardware is configured for.
When the SPI slave driver changes 'spi->mode'
it will be different than the value of this new
member and the SPI master driver will know that
the hardware must be reconfigured (by calling
omap2_mcspi_setup_transfer()).

Fixes: 2bd16e3e23 (spi: omap2-mcspi: Do not configure the controller on each transfer unless needed)
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org
2014-07-03 19:49:05 +01:00
Mark Brown 6eadd84631 Merge remote-tracking branches 'spi/fix/complete', 'spi/fix/efm32', 'spi/fix/omap2-mcspi' and 'spi/fix/qup' into spi-linus 2014-04-10 23:39:52 +01:00
Axel Lin a6f936db64 spi: omap2-mcspi: Convert to use devm_kcalloc
This saves a few unwind code and return proper error if devm_kcalloc fails.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-04-03 11:21:15 +01:00
Mark Brown 1752368064 Merge remote-tracking branches 'spi/topic/omap-uwire', 'spi/topic/omap100k', 'spi/topic/omap2', 'spi/topic/orion', 'spi/topic/pl022', 'spi/topic/qup', 'spi/topic/rspi' and 'spi/topic/s3c24xx' into spi-next 2014-03-30 00:51:27 +00:00
Axel Lin aca0924b48 spi: omap2-mcspi: Convert to let spi core validate transfer speed
Set master->max_speed_hz and master->min_speed_hz then spi core will handle
checking transfer speed. So we can remove the same checking in this driver.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-02-19 13:38:31 +09:00
Axel Lin cd60080fd6 spi: omap2-mcspi: Remove list_empty checking in omap2_mcspi_transfer_one_message
This checking is done in __spi_validate().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-02-19 13:38:31 +09:00
Stefan Sørensen faee9b05f6 spi: omap2-mcspi: Support divide-by-n clock dividers
Currently a divide-by-2^n clock is used, causing a very coarse
clock selection, i.e. a 10MHz device will need to use a 6MHz
clock. The McSPI can also use a divide-by-n clock, this patch
adds support for selecting that when possible.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-02-03 18:25:48 +00:00
Stefan Sørensen 2bd16e3e23 spi: omap2-mcspi: Do not configure the controller on each transfer unless needed
spi_transfer->speed_hz and spi_transfer->bits_per_word used to only be set when
not using the default settings but are not set on every transfer, causing
omap2_mcspi_setup_transfer to be called on each transfer. This patch changes
the check to only call omap2_mcspi_setup_transfer if the settings needs to be
changed.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-02-03 18:25:48 +00:00
Paul Gortmaker 3a44623d5e spi: delete non-required instances of include <linux/init.h>
None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>.  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2014-02-03 12:20:35 +00:00
Victor Kamensky 21b2ce5e99 spi: omap2-mcspi: raw read and write endian fix
All OMAP IP blocks expect LE data, but CPU may operate in BE mode.
Need to use endian neutral functions to read/write h/w registers.
I.e instead of __raw_read[lw] and __raw_write[lw] functions code
need to use read[lw]_relaxed and write[lw]_relaxed functions.
If the first simply reads/writes register, the second will byteswap
it if host operates in BE mode.

Changes are trivial sed like replacement of __raw_xxx functions
with xxx_relaxed variant.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-11-24 14:06:45 +00:00
Mark Brown 52d85ebb7b Merge remote-tracking branch 'spi/topic/bfin' into spi-next 2013-10-25 09:51:21 +01:00
Mark Brown 2ef2e60d2f Merge remote-tracking branch 'spi/topic/atmel' into spi-next 2013-10-25 09:51:21 +01:00
Jarkko Nikula a1829d2b76 spi: Add missing newline to dev_ prints in drivers
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-10-16 19:07:15 +01:00
Illia Smyrnov 5db542ed85 spi: omap2-mcspi: Fix FIFO support for transmit-and-receive mode
This patch fixes MCSPI FIFO buffer support when transmit-and-receive
(full duplex) mode is used. In this mode FIFO can be used for RX or
for TX or for both directions. If FIFO used for both directions the buffer
is split into two 32-byte buffers - one for each direction.
Also for full duplex mode both AEL and AFL need to be set in CHCONF0 register.

Signed-off-by: Illia Smyrnov <illia.smyrnov@globallogic.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-10-09 19:00:58 +01:00
Jingoo Han b95e02b748 spi: omap2-mcspi: use devm_spi_register_master()
Use devm_spi_register_master() to make cleanup paths simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-09-26 11:42:36 +01:00
Mark Brown 85cac43132 Merge remote-tracking branch 'spi/topic/qspi' into spi-next 2013-09-01 13:49:06 +01:00
Jingoo Han 8074cf063e spi: use dev_get_platdata()
Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-08-29 13:56:23 +01:00
Mark Brown f0278a1a40 spi/omap2: Covert to core runtime PM
Signed-off-by: Mark Brown <broonie@linaro.org>
Reviewed-by: Felipe Balbi <balbi@ti.com>
2013-07-29 18:00:20 +01:00
Mark Brown 3d09da11b5 Merge remote-tracking branch 'spi/topic/pdata' into spi-next 2013-06-26 16:21:02 +01:00
Mark Brown 1728ddb2ca Merge remote-tracking branch 'spi/topic/omap' into spi-next 2013-06-26 16:21:01 +01:00
Matt Porter 74f3aaad21 spi: omap2-mcspi: convert to dma_request_slave_channel_compat()
Convert dmaengine channel requests to use
dma_request_slave_channel_compat(). This supports the DT case of
platforms requiring channel selection from either the OMAP DMA or
the EDMA engine. AM33xx only boots from DT and is the only user
implementing EDMA so in the !DT case we can default to the OMAP DMA
filter.

Signed-off-by: Matt Porter <mporter@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-06-24 10:18:40 +01:00
Illia Smyrnov d33f473dcd spi: omap2-mcspi: Add FIFO buffer support
The MCSPI controller has a built-in FIFO buffer to unload the DMA or interrupt
handler and improve data throughput. This patch adds FIFO buffer support for SPI
transfers in DMA mode.

For SPI transfers in DMA mode, the largest possible FIFO buffer size will be
calculated and set up. The FIFO won't be used for the SPI transfers in DMA mode
if: calculated FIFO buffer size is less then 2 bytes or the FIFO buffer size
isn't multiple of the SPI word length.

Signed-off-by: Illia Smyrnov <illia.smyrnov@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-06-17 17:17:23 +01:00
Illia Smyrnov 56cd5c1578 spi: omap2-mcspi: Move bytes per word calculation to the function
Introduce mcspi_bytes_per_word function as replacement for the next code
fragment:

int c = (word_len <= 8)  ? 1 :
	(word_len <= 16) ? 2 :
	/* word_len <= 32 */ 4;

This code used 2 times in current driver code and will be used 2 times in
the next FIFO buffer support patch. Replace it with inline function with clear
name to improve code legibility.

Signed-off-by: Illia Smyrnov <illia.smyrnov@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
2013-06-17 10:13:29 +01:00
Stephen Warren 24778be20f spi: convert drivers to use bits_per_word_mask
Fill in the recently added spi_master.bits_per_word_mask field in as
many drivers as possible. Make related cleanups, such as removing any
redundant error-checking, or empty setup callbacks.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2013-05-29 20:48:17 +01:00
Jingoo Han 24b5a82cf5 spi: use platform_{get,set}_drvdata()
Use the wrapper functions for getting and setting the driver data using
platform_device instead of using dev_{get,set}_drvdata() with &pdev->dev,
so we can directly pass a struct platform_device.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2013-05-23 09:09:55 -05:00
Mark Brown 0514dd76ea spi/omap2: Let device core handle pinctrl
Since commit ab78029 (drivers/pinctrl: grab default handles from device
core) we can rely on device core for handling pinctrl so remove
devm_pinctrl_get_select_default() from the driver.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2013-05-13 18:12:56 +04:00
Wei Yongjun 142e07beab spi: omap2-mcspi: fix error return code in omap2_mcspi_probe()
Fix to return a negative error code from the error handling
case instead of 0, as returned elsewhere in this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2013-04-18 12:04:55 +01:00
Tony Lindgren ddc5cdf161 spi: omap2-mcspi: Fix transfers if DMADEVICES is not set
Selecting CONFIG_DMADEVICES is optional, and we must
be able to continue even without DMA. Otherwise things
like omap4430sdp nfsroot will fail if DMA is not
selected.

Note that the driver already supports PIO mode, but
we fail to fall back to PIO if requesting DMA channels
fails.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
2013-04-15 17:10:59 +01:00