Since

commit 131e663b
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Thu Jul 9 23:32:33 2015 +0200

    drm/gem: rip out drm vma accounting for gem mmaps

there is no need for this any more.

v2: Fixup compile noise spotted by 0-day build.

Link: http://mid.gmane.org/1444894601-5200-9-git-send-email-daniel.vetter@ffwll.chReviewed-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Since David Herrmann's mmap vma manager rework we don't need to grab
dev->struct_mutex any more to prevent races when looking up the mmap
offset. Drop it and instead don't forget to use the unref_unlocked
variant (since the drm core still cares).

Aside: I stumbled over the mmap handler which directly does a
dma_mmap_attrs. But totally fails to grab a reference on the
underlying object and hence looks like it happily just leaks the ptes
since there's no guarantee the mmap isn't still around when
gem_free_object is called. Which the kerneldoc of dma_mmap_attrs
explicitly forbids.

v2: Fixup compile fail 0-day spotted.

Cc: Mark Yao <mark.yao@rock-chips.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

Rather than (incompletely [0]) re-implementing drm_gem_mmap() and
drm_gem_mmap_obj() helpers, call them directly from the rockchip mmap
routines.

Once the core functions return successfully, the rockchip mmap routines
can still use dma_mmap_attrs() to simply mmap the entire buffer.

[0] Previously, we were performing the mmap() without first taking a
reference on the underlying gem buffer.  This could leak ptes if the gem
object is destroyed while userspace is still holding the mapping.
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org

Rather than (incompletely [0]) re-implementing drm_gem_mmap() and
drm_gem_mmap_obj() helpers, call them directly from the rockchip mmap
routines.

Once the core functions return successfully, the rockchip mmap routines
can still use dma_mmap_attrs() to simply mmap the entire buffer.

[0] Previously, we were performing the mmap() without first taking a
reference on the underlying gem buffer.  This could leak ptes if the gem
object is destroyed while userspace is still holding the mapping.
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

In general, the data in drm/rockchip GEM objects is never accessed by
the kernel.  The objects are either accessed by a GPU, by display
controller DMA, or by mmap'ing them to user space.  Thus, these
buffers need not be mapped into kernel address space.

The only exception is the fbdev framebuffer(s), which may be written
in-kernel by fbcon.
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NMark Yao <mark.yao@rock-chips.com>

dma_alloc_attrs() returns NULL if it cannot allocate a dma buffer (or
mapping), not a negative error code.
Rerported-by: NPawel Osciak <posciak@chromium.org>
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NMark Yao <mark.yao@rock-chips.com>

This patch adds the basic structure of a DRM Driver for Rockchip Socs.
Signed-off-by: NMark Yao <mark.yao@rock-chips.com>
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Acked-by: NDaniel Vetter <daniel@ffwll.ch>
Reviewed-by: NRob Clark <robdclark@gmail.com>