Hi Wolfram, W dniu 15.05.2020 o 09:53, Wolfram Sang pisze: > > http://patchwork.ozlabs.org/project/linux-i2c/list/?series=95793 > > (Do you use this driver or a custom one?) Unfortunatly not right now. For historical reasons we have a custom one but I would like to move to this upstream one in near future. > > I'd think that the PCA9641 driver should return -EBUSY if another master > is active, so we'd have the lock on that level. But I may be totally > missing some detail here. That is a good point however right now the logic in i2c-mux.c is like this: ret = muxc->select(muxc, priv->chan_id); if (ret >= 0) ret = i2c_transfer(parent, msgs, num); if (muxc->deselect) muxc->deselect(muxc, priv->chan_id); So this does not really solve my problem - even if we do get the lock by calling select(), we will simply release it as soon as our i2c_transfer() is finished (and will let the other master take it, breaking atomicity of the two operations I need to perform on target device) and this is exactly what I need to avoid. BTW the deselect is called regardless of the return code of select() - even if it returns an error. I'm not sure if this might cause some problems (unbalanced numer of select/deselect operation) but I find it a little odd. Is this deliberate? Best regards, Krzysztof Adamski
