[PATCH v7 3/6] dt-bindings: mailbox: imx-mu: add generic MU channel support

On Thu, Jul 26, 2018 at 4:27 PM, Oleksij Rempel [off-list ref] wrote:

On 26.07.2018 11:49, Jassi Brar wrote:

quoted

On Thu, Jul 26, 2018 at 12:23 PM, Oleksij Rempel
[off-list ref] wrote:

quoted

Each MU has four pairs of rx/tx data register with four rx/tx interrupts
which can also be used as a separate channel.

So the hardware actually supports 4 channels.

quoted

-- #mbox-cells:  Must be 0. Number of cells in a mailbox
+- #mbox-cells:  Must be:
+               0 - for single channel mode. i.MX8* SCU protocol specific.
+               1 - for multichannel (generic) mode.
+

No, please.
DT bindings should reflect the real hardware, and not the software
mode we want the driver to work in.
Please define mbox-cells=1  and have the i.MX8* platform always ask
for channel-0.

We spend already some week to publicly talk about this..

You should have kept me in the loop.
I know, I am not that important, but for the sake of the protocol you
should have CC'ed the mailbox maintainer :)

The problem is, imx8 has multiple MUs

You mean multiple instances of the MU. Some have 4 channels, some 1.
Is that correct?

, only some of them communicate
directly with SCU.

OK

SCU has some well defined protocol and
MU should be used and configured in some SCU specific way. From NXP
perspective, SCU firmware should not be replaceable and from Linux side
seen as part of the HW.

Sure. But the behaviour (protocol) should be implemented in the client
driver, not the controller driver.