regulator: core: if voltage scaling fails, restore original voltage values

Change-Id: I6f41096966aa5e5f9d834049ca9b2ae2d8156285
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Git-commit: 92d7a55879c01b30349045501108e775655a4b92
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[keliu@codeaurora.org: resolve merge conflicts]
Signed-off-by: Ke Liu <keliu@codeaurora.org>
cma: Remove potential deadlock situation

A report was given of a deadlock situation on the cma_mutex:

mutex_lock(cma_mutex)   (*2)
dma_release_from_contiguous
ion_secure_cma_free_chunk
ion_secure_cma_shrinker
shrink_slab
try_to_free_pages
migrate_pages
alloc_contig_range
mutex_lock(cma_mutex)  (*1)
dma_alloc_from_contiguous
ion_alloc

We may need to free CMA allocations while a current CMA allocation is in
progress if CMA is freed from a shrinker. cma_mutex currently protects
two things: the bitmap indicating which pages are allocated/free and
serialization of isolation/migration calls on allocation. There is
no need to take the mutex on free calls though as the pages are
freed back into the system via the regular __free_page call. Move
the free_contig_range call outside the cma_mutex to break the
chain dependency. We can safely free the pages back into the system
before changing the bitmap without any risk of races.

Change-Id: I4989eb2891e502b08db8117a51bd86652e902778
CRs-Fixed: 619644
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
cma: Make locking finer grained

CMA locking is currently very coarse. The cma_mutex protects both
the bitmap and avoids concurrency with alloc_contig_range. There
are several situations which may result in a deadlock on the CMA
mutex currently, mostly involving AB/BA situations with alloc and
free. Fix this issue by protecting the bitmap with a mutex per CMA
region and use the existing mutex for protecting against concurrency
with alloc_contig_range.

Change-Id: I6863ba7ab7fae07c68fee23b0aa4c869244fe2a1
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>