From: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com
[ Upstream commit e557bca49b812908f380c56b5b4b2f273848b676 ]
In typical use cases, the peripheral becomes pm_runtime active as a result of the ALSA/ASoC framework starting up a DAI. The parent/child hierarchy guarantees that the manager device will be fully resumed beforehand.
There is however a corner case where the manager device may become pm_runtime active, but without ALSA/ASoC requesting any functionality from the peripherals. In this case, the hardware peripheral device will report as ATTACHED and its initialization routine will be executed. If this initialization routine initiates any sort of deferred processing, there is a possibility that the manager could suspend without the peripheral suspend sequence being invoked: from the pm_runtime framework perspective, the peripheral is *already* suspended.
To avoid such disconnects between hardware state and pm_runtime state, this patch adds an asynchronous pm_request_resume() upon successful attach/initialization which will result in the proper resume/suspend sequence to be followed on the peripheral side.
BugLink: https://github.com/thesofproject/linux/issues/3459 Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Reviewed-by: Ranjani Sridharan ranjani.sridharan@linux.intel.com Reviewed-by: Rander Wang rander.wang@intel.com Signed-off-by: Bard Liao yung-chuan.liao@linux.intel.com Link: https://lore.kernel.org/r/20220420023241.14335-4-yung-chuan.liao@linux.intel... Signed-off-by: Vinod Koul vkoul@kernel.org Stable-dep-of: c40d6b3249b1 ("soundwire: fix enumeration completion") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/soundwire/bus.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index b7cdfa65157c6..cc4cca0325b98 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -1841,6 +1841,18 @@ int sdw_handle_slave_status(struct sdw_bus *bus, __func__, slave->dev_num);
complete(&slave->initialization_complete); + + /* + * If the manager became pm_runtime active, the peripherals will be + * restarted and attach, but their pm_runtime status may remain + * suspended. If the 'update_slave_status' callback initiates + * any sort of deferred processing, this processing would not be + * cancelled on pm_runtime suspend. + * To avoid such zombie states, we queue a request to resume. + * This would be a no-op in case the peripheral was being resumed + * by e.g. the ALSA/ASoC framework. + */ + pm_request_resume(&slave->dev); } }