+ dbehr@ who recently worked on drm.py and is familiar with cffi

Joe,

We need to add libgbm.so imports using ctypes in drm.py and start using GBM map/unmap so we can take advantage of software tiling/untiling implemented there.
Also, AMD folks need to implement their tiling/untiling in their gbm backend, so please work with Deepak and others from AMD who will be working on gbm.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform/minigbm/+/5f61c792038b93f1215e3f5ae60deb4c6e600674

commit 5f61c792038b93f1215e3f5ae60deb4c6e600674
Author: Joe Kniss <djmk@google.com>
Date: Thu Jun 29 17:37:40 2017

Add tegra_bo_import to query tile format.

When a buffer is imported, knowledge of tiling is needed for later calls
to map.  Add this functionality for tegra gpus.

The Tegra display engine only knows about 3 compression schemes, of
which we only use two (NV_MEM_KIND_C32_2CRA and NV_MEM_KIND_PITCH), these
are correlated to DRM_TEGRA_GEM_TILING_MODE_BLOCK and
DRM_TEGRA_GEM_TILING_MODE_PITCH respectively in the tegra drm driver.

BUG= chromium:653283 , b:38152101
TEST=graphicsSanity on nyan_big

Change-Id: Ie28212494ad109bd8caa929a9271fc4c55c5c977
Reviewed-on: https://chromium-review.googlesource.com/553517
Commit-Ready: Joe Kniss <djmk@google.com>
Tested-by: Joe Kniss <djmk@google.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>

[modify] https://crrev.com/5f61c792038b93f1215e3f5ae60deb4c6e600674/tegra.c

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/557946d18d625f8c14e0a1bf6a23d91b17d70f1d

commit 557946d18d625f8c14e0a1bf6a23d91b17d70f1d
Author: Joe Kniss <djmk@google.com>
Date: Fri Jul 14 02:46:17 2017

Implement python screenshots using GBM library.

... so that untiling is no longer handled in python code.

BUG= chromium:653283 , b:38152101
TEST=Ran tests that use screenshot.py or crtcScreenShot()

Change-Id: Idb4d4933015d70c35a404a6ef0cbc3fbb664f65c
Reviewed-on: https://chromium-review.googlesource.com/550737
Commit-Ready: Joe Kniss <djmk@google.com>
Tested-by: Joe Kniss <djmk@google.com>
Reviewed-by: Joe Kniss <djmk@google.com>

[modify] https://crrev.com/557946d18d625f8c14e0a1bf6a23d91b17d70f1d/client/common_lib/cros/arc.py
[modify] https://crrev.com/557946d18d625f8c14e0a1bf6a23d91b17d70f1d/client/bin/screenshot.py
[add] https://crrev.com/557946d18d625f8c14e0a1bf6a23d91b17d70f1d/client/cros/graphics/gbm.py
[modify] https://crrev.com/557946d18d625f8c14e0a1bf6a23d91b17d70f1d/client/cros/graphics/drm.py
[modify] https://crrev.com/557946d18d625f8c14e0a1bf6a23d91b17d70f1d/client/cros/graphics/graphics_utils.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/autotest/+/1a1a3e19339635cfa8d8c69efa9927612303d3dd

commit 1a1a3e19339635cfa8d8c69efa9927612303d3dd
Author: Joe Kniss <djmk@google.com>
Date: Wed Aug 16 07:17:52 2017

Updating gbm tests.

Adds tests for tilied buffer mmaps.

BUG= chromium:653283 , b:38152101
TEST=cyan graphics_Gbm

Change-Id: Iea0695d64b379de5399a8c4f7812cebe0dd74fb2
Reviewed-on: https://chromium-review.googlesource.com/571304
Commit-Ready: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Joe Kniss <djmk@google.com>
Reviewed-by: Joe Kniss <djmk@google.com>

[modify] https://crrev.com/1a1a3e19339635cfa8d8c69efa9927612303d3dd/client/site_tests/graphics_Gbm/src/gbmtest.c

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/04fd06e418ef3cb3ed5dfb583ac650310177f5b0

commit 04fd06e418ef3cb3ed5dfb583ac650310177f5b0
Author: Satyajit Sahu <satyajit.sahu@amd.com>
Date: Tue Oct 03 21:26:11 2017

amdgpu-addrlib: Expose AddrComputeSurfaceAddrFromCoord

AddrComputeSurfaceAddrFromCoord needs to be called from minigbm
to convert tiled buffer to linear.

BUG=b:38152101,  chromium:653283 
TEST=Tested by running graphics_Sanity autotest and mmap_test.

Change-Id: Id607ca1f9039d99dff141d165647cbca1b0ef671
Signed-off-by: Satyajit Sahu <satyajit.sahu@amd.com>
Reviewed-on: https://chromium-review.googlesource.com/670420
Commit-Ready: Drew Davenport <ddavenport@chromium.org>
Reviewed-by: Dominik Behr <dbehr@google.com>

[rename] https://crrev.com/04fd06e418ef3cb3ed5dfb583ac650310177f5b0/media-libs/amdgpu-addrlib/amdgpu-addrlib-12.0.1-r1.ebuild
[modify] https://crrev.com/04fd06e418ef3cb3ed5dfb583ac650310177f5b0/media-libs/amdgpu-addrlib/files/12.1-amdgpu-addrlib.patch