3d7d916f9b
If we get a timeout sending then this happens:
spi_transfer_one_message()
->transfer_one() AKA spi_geni_transfer_one()
setup_fifo_xfer()
mas->cur_xfer = non-NULL
spi_transfer_wait() => TIMES OUT
if (msg->status != -EINPROGRESS)
goto out
if (ret != 0 ...)
spi_set_cs()
->set_cs AKA spi_geni_set_cs()
# mas->cur_xfer is non-NULL
The above happens _before_ the SPI core calls ->handle_err() AKA
handle_fifo_timeout().
Unfortunately that won't work so well on geni. If we got a timeout
transferring then it's likely that our interrupt handler is blocked,
but we need that same interrupt handler to run and the command channel
to be unblocked in order to adjust the chip select. Trying to set the
chip select doesn't crash us but ends up confusing our state machine
and leads to messages like: Premature done. rx_rem = 32 bpw8
Let's just drop the chip select request in this case. We can detect
the case because cur_xfer is non-NULL--it would have been set to NULL
in the interrupt handler if the previous transfer had finished. Sure,
we might leave the chip select in the wrong state but it's likely it
was going to fail anyway and this avoids getting the driver even more
confused about what it's doing.
The SPI core in general assumes that setting chip select is a simple
operation that doesn't fail. Yet another reason to just reconfigure
the chip select line as GPIOs.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20201217142842.v3.3.I07afdedcc49655c5d26880f8df9170aac5792378@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
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|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.