[B][PATCH 0/1] Fix LP: #1738334 - hisilicon hibmc regression

[Daniel Axtens]

From: Daniel Axtens <dja at axtens.net>

[SRU Justification]

[Impact]
On Artful and Bionic kernels, X fails to start and a kernel splat is printed.

This is because ea642c3216cb ("drm/ttm: add io_mem_pfn callback") is
incomplete: the hisilicon hibmc driver does not contain the callback
and so the kernel tries to execute code at NULL.

[Fix]

Bionic: There is a generic fix in 4.16 at
c67fa6edc8b11afe22c88a23963170bf5f151acf. It is part of a series that
applies this generic fix and does a bunch of cleanups; we can safely
just pick up the generic fix.

Artful: Rather than a generic fix, I have submitted a very very
minimal fix that only touches hibmc. [This has since been applied and
released.]

[Regression Potential]

Artful: Minimal - fix only touches hibmc driver. Tested on D05 board.

Bionic: fix is to generic drm code, but is small and easily reviewable.

[Testcase]
Install patched kernel, try to start X. If it succeeds, the fix
works. If there's a kernel splat, the fix does not work.

Tan Xiaojun (1):
  drm/ttm: add ttm_bo_io_mem_pfn to check io_mem_pfn

 drivers/gpu/drm/ttm/ttm_bo_vm.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

-- 
2.14.1