Re: [PATCH v1 4/4] mailbox: Add support for i.MX7D messaging unit

[Sascha Hauer <s.hauer@pengutronix.de>]

On Wed, Jun 13, 2018 at 08:21:10PM +0800, Dong Aisheng wrote:
> Hi Oleksij,
> 
> On Fri, Jun 1, 2018 at 2:58 PM, Oleksij Rempel <o.rempel@pengutronix.de> wrote:
> > The Mailbox controller is able to send messages (up to 4 32 bit words)
> > between the endpoints.
> 
> Could we really be able to send up to 4 42bit words with this driver?
> 
> It looks to me the current Mailbox framework is more designed for share mem
> transfer which does not fit i.MX MU well.

The mailbox framework just defines channels and messages. A message is a
void * which may contain arbitrary data or even no data at all; some
drivers simply ignore the message pointer, so in fact they act as a
doorbell unit only.

There's nothing about shared memory in the mailbox framework, but of
course you can combine a mailbox driver and shared memory to a remote
message mechanism. That could be done with the i.MX MU aswell and would
indeed be a good match for the hardware.

Sascha

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