On 28-05-20, 13:20, Rob Herring wrote: > Whether Linux > requires serializing mailbox accesses is a separate issue. On that side, > it seems silly to not allow driving the h/w in the most efficient way > possible. That's exactly what we are trying to say. The hardware allows us to write all 32 bits in parallel, without any hardware issues, why shouldn't we do that ? The delay (which Sudeep will find out, he is facing issues with hardware access because of lockdown right now) which may be small in transmitting across a mailbox becomes significant because of the fact that it happens synchronously and the receiver will send some sort of acknowledgement (and that depends on the firmware there) and the kernel needs to wait for it, while the kernel doesn't really need to. There is no reason IMHO for being inefficient here while we can do better. -- viresh
