Selecting memory manager for embedded DRM device

[Rob Clark]

On Mon, Feb 3, 2014 at 11:16 AM, Dmitry Eremin-Solenikov
<dbaryshkov at gmail.com> wrote:
> Hello,
>
> On Mon, Feb 3, 2014 at 7:49 PM, Rob Clark <robdclark at gmail.com> wrote:
>> On Sun, Feb 2, 2014 at 6:50 PM, Dmitry Eremin-Solenikov
>> <dbaryshkov at gmail.com> wrote:
>>> Hello,
>>>
>>> I'm looking onto writing DRM/KMS drivers for few pieces of
>>> embedded equipment. I stumbled upon selecting GEM/TTM/whatever
>>> for them. Could you please guide me?
>>
>> The common choices are either:
>>
>>   * TTM + GEM userspace interface (nouveau and radeon)
>>   * or just GEM (intel, and most of the ARM devices)
>>
>> TTM seems to be mostly advantageous if you need to manage migration
>> between VRAM / GART / system RAM.  But it sounds like you are talking
>> about a UMA system, so maybe TTM doesn't help you as much.
>
> Thank you for the answer. Indeed I had the feeling that just GEM would be
> work for UMA devices. I'm interested about the driver for my second hardware.
> It's a separate graphics chip with separate VRAM, no access to system
> memory and nearly no advanced capabilities (few 2D accelerations,
> but nothing fancy). Would that require TTM, some special setup of GEM
> or something completely different?
>

for the VRAM device, it seems like TTM could be useful.  I guess start
with that device and checkout TTM.  By the time you've done that,
you'll know TTM well enough to decide if you also want to use it for
the UMA device.

BR,
-R

>
> --
> With best wishes
> Dmitry