io_mutex is taken by spi_setup() and spi-mux's .setup() callback calls
spi_setup() which results in a nested lock of io_mutex.
add_lock is taken by spi_add_device(). The device_add() call in there
can result in calling spi-mux's .probe() callback which registers its
own spi controller which in turn results in spi_add_device() being
called again.
To fix this initialize the controller's locks already in
spi_alloc_controller() to give spi_mux_probe() a chance to set the
lockdep subclass.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211013133710.2679703-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Common pattern of handling deferred probe can be simplified with
dev_err_probe(). Less code and the error value gets printed.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200901152713.18629-6-krzk@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
It is not valid to cache/short out selection of the mux.
mux_control_select() only locks the mux until mux_control_deselect()
is called. mux_control_deselect() may put the mux in some low power
state or some other user of the mux might select it for other purposes.
These things are probably not happening in the original setting where
this driver was developed, but it is said to be a generic SPI mux.
Also, the mux framework will short out the actual low level muxing
operation when/if that is possible.
Fixes: e9e40543ad ("spi: Add generic SPI multiplexer")
Signed-off-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/20200525104352.26807-1-peda@axentia.se
Signed-off-by: Mark Brown <broonie@kernel.org>
Add a SPI device driver that sits in-band and provides a SPI controller
which supports chip selects via a mux-control. This enables extra SPI
devices to be connected with limited native chip selects.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200204032838.20739-3-chris.packham@alliedtelesis.co.nz
Signed-off-by: Mark Brown <broonie@kernel.org>
Uwe Kleine-König
Krzysztof Kozlowski
Peter Rosin
Chris Packham