On Tue 09 May 19:33 PDT 2017, Jassi Brar wrote:

On Wed, May 10, 2017 at 12:41 AM, Bjorn Andersson
[off-list ref] wrote:

quoted

On Tue 09 May 09:41 PDT 2017, Jassi Brar wrote:

[..]

quoted

The part where this piece of hardware differs from the other mailboxes
is that TX is done as send_data() returns and in the realm of the
mailbox there is no such thing as "tx done". So how about we extend the
framework to handle stateless and message-less doorbells?

This is a very common usecase. It would be unfair to other platforms
to modify the API just because you find it awkward to call
mbox_client_txdone() right after mbox_send_message(). For example,
drivers/firmware/tegra/bpmp.c
I'd much rather have mbox_send_message_and_tick() than implant a new api.

I wasn't proposing to implement a new API; for mailbox controllers with
tx method set to POLL the client will only have call mbox_send_data()
nothing else. So I proposed [1] yesterday, that will make the apcs
controller behave just like this case.


Looking at it again, making sure that tx method is TXDONE_BY_ACK should
make mbox_client_txdone() essentially a nop, only locking the channel
spinlock twice and then returning, as send_data() didn't leave any data
in the queue. Is my understanding of this correct?

So please let me know what you think about [1], if you don't like it
I'll fix the things pointed to by Stephen and we'll have to live with
the two calls.

[1] https://patchwork.kernel.org/patch/9718931/

Regards,
Bjorn