Currently the OF DMA code uses a spin lock to protect the of_dma_list from
concurrent access and a per controller reference count to protect the controller
from being freed while a request operation is in progress. If
of_dma_controller_free() is called for a controller who's reference count is not
zero it will return -EBUSY and not remove the controller. This is fine up until
here, but leaves the question what the caller of of_dma_controller_free() is
supposed to do if the controller couldn't be freed. The only viable solution
for the caller is to spin on of_dma_controller_free() until it returns success.
E.g.
do {
ret = of_dma_controller_free(dev->of_node)
} while (ret != -EBUSY);
This is rather ugly and unnecessary and none of the current users of
of_dma_controller_free() check it's return value anyway. Instead protect the
list by a mutex. The mutex will be held as long as a request operation is in
progress. So if of_dma_controller_free() is called while a request operation is
in progress it will be put to sleep and only wake up once the request operation
has finished.
This means that it is no longer possible to register or unregister OF DMA
controllers from a context where it's not possible to sleep. But I doubt that
we'll ever need this.
Also rename of_dma_get_controller back to of_dma_find_controller.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
of_dma_request_slave_channel() currently does not drop the reference to the
dma_spec of_node if no DMA controller matching the of_node could be found. This
patch fixes it by always calling of_node_put().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
list_for_each_entry is able to handle empty lists just fine, there is no need
to make sure that the list is non empty.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
In of_dma_controller_register() routine we are calling of_get_property() as an
parameter to be32_to_cpup(). In case the property doesn't exist we will get a
crash.
This patch changes this code to check if we got a valid property first and then
runs be32_to_cpup() on it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
No DMA of-function alters the name, so this patch changes the name arguments
to be constant. Most drivers will probably request DMA channels using a
constant name.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
It's possible to have an inconsistency in the list due to unprotected operation
on it. The patch adds a proper locking on the list operation.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
The memory allocated to ofdma might be a leakage when error occurs.
Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
