There are 3 big benefits to suballocating a single big DMA buffer
for command submission:
1. Avoid hammering CMA. The old way of allocating and freeing a DMA
buffer for each submission was hitting some of the real slow
pathes in CMA, as this allocator was not designed for a concurrent
small buffers load.
2. Less TLB flushes on IOMMUv2. If a new command buffer is mapped into
the GPU address space the MMU TLBs need to be flushed. By having
one big buffer statically mapped to the GPU, a lot of those flushes
can be avoided.
3. No funky workarounds for GC3000. The FE TLB flush on GC3000 isn't
reliable. To work around that we tried to lay out the cmdbufs in
the GPU address space in a way to avoid this issue. This hasn't
always worked if the address space is crowded. A single statically
mapped buffer avoids the erratum completely.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
With MMUv2 all buffers need to be mapped through the MMU once it
is enabled. Align the buffer size to 4K, as the MMU is only able to
map page aligned buffers.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
The GPU virtual address for the command buffers differs depending on
the IOMMU version. Move the calculation of the iova into etnaviv
mmu, to enable proper dispatch.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
The GPU code doesn't need to deal with the IOMMU directly, instead
it can all be hidden behind the etnaviv mmu interface. Move the
last remaining part into etnaviv mmu.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
This adds the etnaviv DRM driver and hooks it up in Makefiles
and Kconfig.
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
