On Mon, 25 Jun 2018 12:58:56 +0200, Shreyas NC wrote:
From: Sanyog Kale sanyog.r.kale@intel.com
Currently, the stream concept is limited to single Master and one or more Codecs.
This patch extends the concept to support multiple Master(s) sharing the same reference clock and synchronized in the hardware. Modify sdw_stream_runtime to support a list of sdw_master_runtime for the same. The existing reference to a single m_rt is removed in the next patch.
Typically to lock, one would acquire a global lock and then lock bus instances. In this case, the caller framework(ASoC DPCM) guarantees that stream operations on a card are always serialized. So, there is no race condition and hence no need for global lock.
Bus lock(s) are acquired to reconfigure the bus while the stream is set-up. So, we add sdw_acquire_bus_lock()/sdw_release_bus_lock() APIs which are used only to reconfigure the bus.
Signed-off-by: Sanyog Kale sanyog.r.kale@intel.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Shreyas NC shreyas.nc@intel.com
drivers/soundwire/bus.h | 2 ++ drivers/soundwire/stream.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/linux/soundwire/sdw.h | 4 ++++ 3 files changed, 47 insertions(+)
diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h index 3b15c4e..b6cfbdf 100644 --- a/drivers/soundwire/bus.h +++ b/drivers/soundwire/bus.h @@ -99,6 +99,7 @@ struct sdw_slave_runtime {
- this stream, can be zero.
- @slave_rt_list: Slave runtime list
- @port_list: List of Master Ports configured for this stream, can be zero.
*/
- @stream_node: sdw_stream_runtime master_list node
- @bus_node: sdw_bus m_rt_list node
struct sdw_master_runtime { @@ -108,6 +109,7 @@ struct sdw_master_runtime { unsigned int ch_count; struct list_head slave_rt_list; struct list_head port_list;
- struct list_head stream_node; struct list_head bus_node;
};
diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index 8974a0f..eb942c6 100644 --- a/drivers/soundwire/stream.c +++ b/drivers/soundwire/stream.c @@ -747,6 +747,7 @@ struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name) return NULL;
stream->name = stream_name;
INIT_LIST_HEAD(&stream->master_list); stream->state = SDW_STREAM_ALLOCATED;
return stream;
@@ -1234,6 +1235,46 @@ struct sdw_dpn_prop *sdw_get_slave_dpn_prop(struct sdw_slave *slave, return NULL; }
+/**
- sdw_acquire_bus_lock: Acquire bus lock for all Master runtime(s)
- @stream: SoundWire stream
- Acquire bus_lock for each of the master runtime(m_rt) part of this
- stream to reconfigure the bus.
- */
+static void sdw_acquire_bus_lock(struct sdw_stream_runtime *stream) +{
- struct sdw_master_runtime *m_rt = NULL;
- struct sdw_bus *bus = NULL;
- /* Iterate for all Master(s) in Master list */
- list_for_each_entry(m_rt, &stream->master_list, stream_node) {
bus = m_rt->bus;mutex_lock(&bus->bus_lock);- }
+}
So it's nested locks? Then you'd need some more trick to deal with the lockdep. I guess you'll get the false-positive deadlock detection by this code when the mutex lock debug is enabled.
Also, is the linked order assured not to lead to a real deadlock?
+/**
- sdw_release_bus_lock: Release bus lock for all Master runtime(s)
- @stream: SoundWire stream
- Release the previously held bus_lock after reconfiguring the bus.
- */
+static void sdw_release_bus_lock(struct sdw_stream_runtime *stream) +{
- struct sdw_master_runtime *m_rt = NULL;
- struct sdw_bus *bus = NULL;
- /* Iterate for all Master(s) in Master list */
- list_for_each_entry(m_rt, &stream->master_list, stream_node) {
bus = m_rt->bus;mutex_unlock(&bus->bus_lock);- }
... and this looks bad. The loop for unlocking should be traversed reversely.
thanks,
Takashi