Re: [PATCH 2/5] iommu/ipmmu-vmsa: Add device tree bindings documentation

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Geert,

On Monday 31 March 2014 10:39:48 Geert Uytterhoeven wrote:
> On Sat, Mar 29, 2014 at 12:36 AM, Laurent Pinchart wrote:
> > +Required Properties:
> > +
> > +  - compatible: Must contain "renesas,ipmmu-vmsa".
> > +  - reg: Base address and size of the IPMMU registers.
> > +  - interrupts: Specifier for the MMU fault interrupt.
> 
> Does it make sense to have a property for the number of micro-TLBs,
> or is this handled transparently?
> 
> E.g. ipmmu_mx has 24 micro-TLBs, but ipmmu_mp has 30.

The IPMMU driver doesn't need to know the number of micro-TLBs, so we should 
be fine without specifying it in DT. The micro-TLBs are configured when a bus 
master device is attached or detached, and at that point the device provides 
its micro-TLB number.

The only reason I can foresee why the number of micro-TLBs would be useful is 
to iterate over micro-TLBs when the driver probes the device to disable them 
all. A mask would probably be better than a number in that case, and I think 
we can always add that later if we find a need for it.

-- 
Regards,

Laurent Pinchart