[PATCH v9 5/9] mailbox: add CIX mailbox driver

[Arnd Bergmann]

On Sun, Jul 13, 2025, at 19:00, Jassi Brar wrote:
> On Tue, Jul 8, 2025 at 8:54 AM Guomin chen <guomin.chen at cixtech.com> wrote:
> ....
>> > > +/* [0~7] Fast channel
>> > > + * [8] doorbell base channel
>> > > + * [9]fifo base channel
>> > > + * [10] register base channel
>> > > + */
>> > > +#define MBOX_FAST_IDX          7
>> > > +#define MBOX_DB_IDX            8
>> > > +#define MBOX_FIFO_IDX          9
>> > > +#define MBOX_REG_IDX           10
>> > > +#define CIX_MBOX_CHANS         11
>> > > +
>> > if it is not really a single controller owning different channels,
>> > maybe implement only what you currently use.
>> >
>> As mentioned in the previous email, a single controller can support
>> multiple different channels.
>>
> OK. I am not too worried about having all variants in one driver esp
> when it is manageable and share the code.
> Unless I am overlooking something. Arnd?

My main worry here is that the types are all quite different: while
the doorbell and fast mailboxes are what a lot of other drivers have,
the FIFO mode does not seem to be a good fit for the mailbox subsystem
but instead looks like a more generic firmware interface with variable
length messages.

For those, I think a higher-level driver with fixed data structures
passed through the hardware interface seems more appropriate.

Are there any other mailbox drivers that just use the mailbox to
tunnel variable-length messages?

     Arnd