From 0c4a1049cf298721eaec4553d3d5039798086e12 Mon Sep 17 00:00:00 2001 From: Sanyog Kale Date: Fri, 27 Jul 2018 14:44:13 +0530 Subject: soundwire: Add support to lock across bus instances 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 Signed-off-by: Shreyas NC Acked-by: Pierre-Louis Bossart Signed-off-by: Vinod Koul --- drivers/soundwire/stream.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'drivers/soundwire/stream.c') diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index e5c7e1ef6318..b52903fe6f31 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; @@ -1245,6 +1246,48 @@ 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. + * NOTE: This function is called from SoundWire stream ops and is + * expected that a global lock is held before acquiring bus_lock. + */ +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); + } +} + +/** + * 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_reverse(m_rt, &stream->master_list, stream_node) { + bus = m_rt->bus; + mutex_unlock(&bus->bus_lock); + } +} + static int _sdw_prepare_stream(struct sdw_stream_runtime *stream) { struct sdw_master_runtime *m_rt = stream->m_rt; -- cgit