typos in commit title...
On 4/20/23 05:16, Krzysztof Kozlowski wrote:
The Soundwire master controllers might want to check for bus->md
Apologies for being pedantic but 'manager' and 'controller' are different concepts in SoundWire, see DisCo spec. It's not a 1:1 mapping, a controller can rely on M managers
initialization to avoid race between early interrupt and finish of sdw_bus_master_add()/sdw_master_device_add(). Such early interrupt can happen if Soundwire devices are not powered off during their probe.
Add a store release barrier, so the Soundwire controllers can safely check it in concurrent (e.g. in interrupt) way.
Can you elaborate on the race condition? I am not following what breaks, and what entity generates the 'early interrupt'.
I am specifically concerned about adding this in common code without any matching smp_load_acquire() - which is only added in the following patch for the Qualcomm manager only, but not added for Intel/AMD managers. Is this not a problem?
Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
Cc: Patrick Lai quic_plai@quicinc.com
drivers/soundwire/master.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/soundwire/master.c b/drivers/soundwire/master.c index 9b05c9e25ebe..d5bf13e7e602 100644 --- a/drivers/soundwire/master.c +++ b/drivers/soundwire/master.c @@ -161,7 +161,12 @@ int sdw_master_device_add(struct sdw_bus *bus, struct device *parent, /* add shortcuts to improve code readability/compactness */ md->bus = bus; bus->dev = &md->dev;
- bus->md = md;
/*
* Make sure the contents of md is stored before storing bus->md.* Paired with new slave attached and slave status interrupts* on the Soundwire master side.*/smp_store_release(&bus->md, md);
pm_runtime_set_autosuspend_delay(&bus->md->dev, SDW_MASTER_SUSPEND_DELAY_MS); pm_runtime_use_autosuspend(&bus->md->dev);