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

[Cyril Bur]

On Tue, 2017-01-10 at 09:25 +1030, Andrew Jeffery wrote:
> On Tue, 2017-01-10 at 09:09 +1100, Cyril Bur wrote:
> > On Sun, 2017-01-08 at 15:45 -0600, Benjamin Herrenschmidt wrote:
> > > On Tue, 2017-01-03 at 11:54 +1030, Andrew Jeffery wrote:
> > > > > > I think we should rename the IOCTL as what we do below doesn't
> > > > > > necessarily raise an interrupt.
> > > > > >  
> > > > > 
> > > > >  
> > > > > Agreed, taking unput :). ASPEED_MBOX_IOCTL_WRITE_BYTE ?
> > > > 
> > > > That suggestion works for me.
> > 
> > Sorry about the blank one, I'll try typing something this time.
> > 
> > > If we are going to do that, maybe we should make this a write()
> > > at a specific lpos...
> > > 
> > 
> > Andrew, Joel what do you think of this, a write of count 1 at a
> > specific pos. I like this since it removes ioctls all together and
> > isn't any harder for userspace.
> 
> 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
> 

Ok so I started writing it - and I thought myself, wait why limit to
single byte writes of lpos is non-zero... I mean, they can do what they
want... what if they want to update two consequtive bytes, it seems
silly to have to require two write()s to do that no?

> 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).
> 
> Andrew