On 20/04/2023 18:42, Pierre-Louis Bossart wrote: > 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 I wrote master, not manager. For the Qualcomm case one controller is one master, but in general I try to avoid the master/slave terminology. > >> 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'. The condition is explained in next patch. If you think it's better, I can squash it with next. If the condition is still not clear, drop a note in next patch, so I will elaborate there. > > 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? Shouldn't be. The barrier just won't be effective for these drivers, but that should not be a problem, because I also did not add to these checking bus->md in a concurrent path. Basically the barrier here is necessary because I want to check bus->md in Qualcomm master interrupt handler. Best regards, Krzysztof
