[PATCH v2 4/5] drivers/mailbox: Add aspeed ast2400/ast2500 mbox driver

[Cyril Bur]

On Mon, 2017-01-09 at 22:28 -0600, Benjamin Herrenschmidt wrote:
> On Tue, 2017-01-10 at 09:25 +1030, Andrew Jeffery wrote:
> > I'm in favour of removing the ioctl. So the logic would be:
> > 
> > 1. If lpos is zero, assume a MBOX_NUM_DATA_REGS-sized write as we do
> > currently
> > 2. If lpos is non-zero, assume a single byte write
> > 
> > On that, should we be testing the assumptions about buffer sizes?
> > Currently we don't (we use the MBOX_NUM_DATA_REGS rather than count).
> 
> I would enforce the lpos is some specific magic value such as 0x1000
> for the special write bcs we might want to support partial writes
> inside the 16 bytes area...

So, its basically no more work (I think...) to just have partial
writes, which... satisfy this requirement no?

Just so we're on the same page - theres nothing 'special' about the
write it's just that he other end has mapped that 'data' register to
trigger an interrupt... the kernel doesn't know that nor does it need
to, the write is like any other, the interrupt gets triggered by
hardware.

> 
> Cheers,
> Ben.
>