On Tue, Jan 22, 2019 at 03:05:23PM -0600, Pierre-Louis Bossart wrote: > On 1/22/19 1:04 PM, Mark Brown wrote: > > On Thu, Jan 10, 2019 at 02:11:32PM -0600, Pierre-Louis Bossart wrote: > > > Messages can be as big as the mailbox, which is hardware dependent. It could > > > be from a few bytes to a larger e.g. 4k page or more, and indeed we need to > > > keep the lock. > > Is this copying into an actual mailbox or into some data structure in > > memory? It looked like it's copying into a buffer for sending rather > > than the mailbox. > I realize between your feedback and Daniel's that we have a terminology > issue. On the Intel side we don't have a dedicated hardware mailbox unit, > it's only doorbell registers and shared memory windows. Ah, that's what I thought was going on. What I was expecting was a sequence of operations along the lines of: 1. Allocate a buffer for the message. 2. Fill in the message. 3. Mark the message as readable by the DSP. so you only need locking for steps 1 and 3 (and a similar path on return).
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