Re: [PATCH] omap2+: add drm device

Tomi Valkeinen
2012-03-08T07:47:23Z

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On Wed, 2012-03-07 at 09:59 -0600, Gross, Andy wrote:
> On Wed, Mar 7, 2012 at 6:05 AM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> >
> > Does this "DMM has become synonymous" mean that people just started
> > calling TILER DMM, and thus the name has stuck, or are there technical
> > reasons to handle it as DMM in the kernel? If the former, and if TILER
> > is the technically exact name for it, perhaps it would make sense to
> > call it TILER, as that's what (at least I) would be looking for if I
> > read the TRM and try to find the code for the TILER.
> >
> > Tomi
>
> Well the breakdown of the DMM/Tiler kind of goes like this. The DMM
> defines a set of registers used to manipulate the PAT table that backs
> the address space with physical memory. The Tiler portion of the DMM
> really just describes the address space that is exposed. Depending on
> what address range you access, you'll get a different mode of access
> and rotation. Management of the address space is attributed to the
> Tiler as well and that is where we have managed the address space and
> provided APIs to reserve address space and pin/unpin memory to those
> regions.
>
> From a hardware perspective, we need access to the resources provided
> by the DMM so that we can do the PAT programming and that can only be
> gotten from the hwmod entry. And if you use the hwmod device entry,
> you have to match the name used for that entry.

Ok. Thanks for the detailed explanation =).

Tomi

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