Some users have reported that in polled mode the driver fails randomly
to read the last word of the transfer.
The end condition used for the transmissions (in polled and irq mode)
has been the TX_EMPTY flag. But Lars-Peter Clausen has identified a delay
from the TX_EMPTY to the actual end of the data rx.
I believe that this race condition has not been detected until now
because of the latency added by the IRQ handler or the PCIe bridge.
This bugs affects setups with low latency access to the spi core.
This patch replaces the readout logic:
For all the words, except the last one, the TX_EMPTY flag is used (and
cached).
If !TX_EMPY or is the last word. The status register is read and the
RX_EMPTY flag is used.
The performance is not affected: there is an extra read of the
Status Register, but the readout can start as soon as there is a word
in the buffer.
Reported-by: Edward Kigwana <ekigwana@scires.com>
Initial-fix-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
The ACK of an inexistent IRQ can trigger an spurious IRQ that breaks the
txrx logic. This has been observed on axi_quad_spi:3.2 core.
This patch only ACKs IRQs that have not been Acknowledge jet.
Reported-by: Edward Kigwana <ekigwana@scires.com>
Tested-by: Edward Kigwana <ekigwana@scires.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Once the module process a transfer in irq mode, the next poll transfer
will not work because the transmitter is left in inhibited state.
Fixes: 22417352f6 (Use polling mode on small transfers)
Reported-by: Edward Kigwana <ekigwana@scires.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
On 1 and 2 bytes per word, the transfer of the 3 last bytes will access
memory outside tx_ptr.
Although this has not trigger any error on real hardware, we should
better fix this.
Fixes: 24ba5e593f (Remove rx_fn and tx_fn pointer)
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This reverts commit 99082eab63 since it
breaks the build due to differing implementations of iowrite() and
ioread().
Signed-off-by: Mark Brown <broonie@kernel.org>
The core only supports up to 32 slaves, and the chipselect function
expects the same.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Small transfers generally can be accomplished faster in polling mode.
This patch select the transfer which size is bellow the buffer size to
be done on polling mode
Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Simplify the code by using the unit used on most of the code logic.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Simplify the code by using the unit used on most of the code logic.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
spi_rx handles the case where the buffer is null. Nevertheless spi_tx
did not handle it, and was handled by the caller function.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Simplify the code by removing the tx and and rx function pointers and
substitute them by a single function.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The core controls the chip select lines individually.
By default, all the lines are consider active_low. After
spi_setup_transfer, it has its real value.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
When no irq is used, there is no need to inhibit the transmission for
every transaction. This inhibition was implemented to avoid a race
condition with the irq handler.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The core can run in polling mode. In fact, the performance of the core
is similar (or even better), due to the fact most of the spi
transactions are just a couple of bytes and there is one irq per
transactions.
When an mtd device is connected via spi, reading 8MB of data produces
more than 80K interrupts (with irq disabling, context swith....)
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The control register has not changed since the previous access.
Therefore we can use the cached value and safe one bus access.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
On the transmission loop, check for remaining bytes at the loop
condition.
This way we can handle transmissions of 0 bytes and clean the code.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Instead of enabling the IRQ and disabling it for every transaction.
Specially the small transactions (1,2 words) benefit from removing 3 bus
accesses.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Instead of checking the TX_FULL flag for every transaction, find out the
size of the buffer at probe time and use it.
To avoid situations where the core had some data on the buffer before
initialization, the core is reseted before the buffer size is detected
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
The number of words in the read buffer will be exactly the same as the
number of words written on write buffer, once the transaction has
finished.
Instead of cheking the rx_empty flags for every word simply save the
number of words written by fill_tx_fifo.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Hardware supports LOOP mode. Support it also in the driver.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Hardware supports LSB_FIRST mode. Support it also in the driver.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
There is no need to init .owner field.
Based on the patch from Peter Griffin <peter.griffin@linaro.org>
"mmc: remove .owner field for drivers using module_platform_driver"
This patch removes the superflous .owner field for drivers which
use the module_platform_driver API, as this is overriden in
platform_driver_register anyway."
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
The Xilinx SPI driver initializes the bus_num field of the SPI master to
pdev->dev.id. pdev->dev.id is always 0 for platform devices which causes bus
number conflicts for the SPI controller when creating multiple device instances
of the driver. Instead use pdev->id which will have the assignt platform device
id. If the device is instantiated via devicetree pdev->id is -1 which will cause
the SPI core to dynamically assign a id (or use the id defined via a alias in
the devicetree).
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
Ricardo Ribalda Delgado
Mark Brown
Michal Simek
Lars-Peter Clausen