[PATCH] [RFC PATCH] DRM: add DRM Driver for Samsung SoC EXYNOS4210.

[Sascha Hauer]

On Wed, Aug 03, 2011 at 07:54:24PM +0100, Alan Cox wrote:
> > if so, I am aware of it but his patch isn't applied to drm-next yet and 
> > so my drm driver doesn't include his patch. of course I will reuse it 
> > and remove the samsung_ namespace as you pointed out if the patch is 
> > applied to drm-next.
> 
> It would be nice it was as its also the same as the code being carried in
> the GEM glue for the gma500 driver so we now have 3 users (plus i915 can
> use it).
> 
> I agree with Sascha Hauer that a lot more could be shared with other
> (particularly future 'dumb') drivers. I think however it would be better
> to see what wants moving *after* such drivers are merged rather than
> guess in advance and do unneeded work and get it wrong anyway.

Forking is much easier than merging, so I really want to share as much
as possible from the start. I'm not aware of any SoC having dedicated
graphics memory, they all use system memory and the only difference
I know is that some systems have a iommu and others don't.

Also, don't forget that we do not talk about three major graphic card
vendors, but about dozens of SoC vendors with different graphic cores.

> 
> It's a nice reference driver for anyone else writing a DRM driver too.
> 
> Architecturally it's actually not quite as neat a fit for PC dumb devices
> as it might first seem though - in the PC world framebuffer case for a lot
> of cards I suspect you actually want to use real GEM objects.
> 
> In the PC case you do get multiple framebuffers allocated not all of
> which are in use so for cards with limited memory a true GEM object is
> useful. This would then be 'pinned' and 'unpinned' by copying it
> to/from video RAM and invalidating the mappings so mmap users fault with
> the new address next access)

/me has just learned something about GEM ;)

Sascha

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