Re: [PATCH] omap2+: add drm device

Tomi Valkeinen
2012-03-14T13:07:50Z

On Wed, 2012-03-14 at 07:55 -0500, Rob Clark wrote:
> On Wed, Mar 14, 2012 at 7:38 AM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> > Hi,
> >
> > On Tue, 2012-03-13 at 15:34 -0500, Rob Clark wrote:
> >> From: Andy Gross <andy.gross@ti.com>
> >>
> >> Register OMAP DRM/KMS platform device, and reserve a CMA region for
> >> the device to use for buffer allocation. DMM is split into a
> >> separate device using hwmod.
> >
> > What's the diff with this and the previous one?
>
> Moving drm.c to mach-omap2 (header could not move because
> omap_reserve() is in plat-omap.. but this seems to be the same as what
> is done for dspbridge).
>
> > I see you still have the platform data there. You didn't comment on
> > that. Where is it used after the board files are gone when we use DT?
>
> I was kind-of thinking that there would be some DT<->data-structure
> glue somewhere.. not sure if this goes in mach-omap2 or in the driver
> itself, but presumably it is needed somewhere.
>
> It is only really special cases where some board specific device-tree
> data is needed, so it seems like this is ok to handle later.

Afaik DT data should only contain information about the hardware. This
is SW configuration, so I think DT people won't accept things like that.

> > And how about the size of the contiguous memory area, it was left a bit
> > unclear to me why it cannot be dynamic.
>
> I don't think there is anything preventing adding a bootarg, but I
> think it is not essential so ok to add later

Well, maybe not essential to you =). But you are reserving 32MB memory,
which is quite a big amount. Even if the reserved memory can be used for
some other purposes, it's still a big chunk of "special" memory being
reserved even if the user doesn't use or have a display at all.

Well, it's not an issue for me either, but I just feel that doing things
like that without allowing the user to avoid it is a bit bad thing.

Btw, do you know why the dma_declare_contiguous() takes a dev pointer as
an argument, if the memory is not private to that device? (at least I
understood from you that the memory can be used for other purposes).

Tomi