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

[Sascha Hauer]

Hi,

On Fri, Jul 29, 2011 at 04:24:35PM +0900, Inki Dae wrote:
> This patch is a DRM Driver(only including FIMD Driver yet)
> for Samsung SoC Exynos4210. and as RFC, I am sending only DRM driver part.
> 
> this patch is based on git repository below:
> git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6.git,
> branch: drm-next
> commit-id: 5a96a899bbdee86024ab9ea6d02b9e242faacbed
> 
> We tried to re-use lowlevel codes of the FIMD driver(s3c-fb.c
> based on Linux framebuffer) but couldn't so because lowlevel codes
> of s3c-fb.c are included internally and so this driver shares only
> platform device.
> 
> Sub drivers such as fimd or hdmi have indenpendent platform device and
> Platform driver and when driver's probe is called, the driver object
> including callbacks(for hardware control) would be registered to
> Samsung drm driver. and then when samsung drm driver is probed,
> each probe callback of the driver object registered is called so that
> additional callbacks for drm framework would be set at this time.
> 
> We used GEM framework for buffer management and this driver supports
> only physically continuous memory yet(non-iommu). and for buffer allocation,
> we used DMA APIs(dma_alloc_writecombine) but we will change it to CMA instead
> of DMA APIs later.
> 
> Refer to this link for CMA(Continuous Memory Allocator):
> http://lkml.org/lkml/2011/7/20/45
> 
> Future works:
> - HDMI support.
> - drm plane feature support.
>   refer to this link for drm plane feature:
>   http://www.spinics.net/lists/dri-devel/msg11778.html
> - change the allocator to CMA.
> - iommu support.(for non-continuous physical memory usage)
> - fimd driver update.
> - add exception codes and code clean.
> 
> to support all features above, we need long time and hard work.
> so we wish that only some features(fimd and non-iommu) are applied to
> mainline first.
> 
> We would be pleased you to give us your comments.

So far I only had a quick look over the driver. You might know that
I wrote a Freescale i.MX drm driver which I posted to the list some time
ago.

My driver lacks GEM support which your driver has, so I specifically
looked at this part. It seems we could reuse the GEM code on i.MX and
probably on most other ARMs aswell. Can you split out this code
and remove the samsung_ namespace?

btw you should probably Cc the arm Linux Kernel mailing list as this
is the list where your users are.

I look forward to have the first ARM drm drivers mainline, so I really
appreciate your work :)

Sascha

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