[PATCH 0/5] OMAPFB: use dma_alloc instead of omap's vram

* Tomi Valkeinen [off-list ref] [121116 01:08]:

Hi Tony,

On 2012-11-13 00:50, Tony Lindgren wrote:

quoted

* Tomi Valkeinen [off-list ref] [121112 02:27]:

quoted

Hi,

This series changes omapfb to use standard dma_alloc funcs instead of omap
specific vram allocator. This let's us remove the omap vram allocator, making
omapfb platform independent.

However, note that using standard dma funcs causes the following downsides:

1) dma_alloc_attrs doesn't let us allocate at certain physical address.
However, this should not be a problem as this feature of vram allocator
is only used when reserving the framebuffer that was initialized by the
bootloader, and we don't currently support "passing" a framebuffer from
the bootloader to the kernel anyway.

2) dma_alloc_attrs, as of now, always ioremaps the allocated area, and
we don't need the ioremap when using VRFB. This patch uses
DMA_ATTR_NO_KERNEL_MAPPING for the allocation, but the flag is currently
not operational.

3) OMAPFB_GET_VRAM_INFO ioctl cannot return real values anymore. I
changed the ioctl to return 64M for all the values, which, I hope, the
applications will interpret as "there's enough vram".

4) "vram" kernel parameter to define how much ram to reserve for video use no
longer works. The user needs to enable CMA and use "cma" parameter.

Great, thanks for fixing these. Could you please queue these into
a separate branch against v3.7-rc5 that I can also merge into
omap-for-v3.8/cleanup-headers-prepare-multiplatform-v3?

Should we enable CMA by default in omap2plus_defconfig? And perhaps on
omap1 also?

Yes if that's now needed for DSS.
 

I have to say I don't know the details of the dma allocation, but afaik
there are no drawbacks with CMA. Although it is still marked
EXPERIMENTAL in the kconfig...

I guess that's still fine as that's what we're supposed to use :)

Regards,

Tony