Re: [PATCH] omap2+: add drm device

Gross, Andy
2012-03-07T15:59:40Z

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.

Regards,

Andy
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