commit 55c4b906aa2aec3fa66310ec03c6842e34a04b2a upstream.

gcc-6 warns about a pointless loop in exynos_drm_subdrv_open:

drivers/gpu/drm/exynos/exynos_drm_core.c: In function 'exynos_drm_subdrv_open':
drivers/gpu/drm/exynos/exynos_drm_core.c:104:199: error: self-comparison always evaluates to false [-Werror=tautological-compare]
  list_for_each_entry_reverse(subdrv, &subdrv->list, list) {

Here, the list_for_each_entry_reverse immediately terminates because
the subdrv pointer is compared to itself as the loop end condition.

If we were to take the current subdrv pointer as the start of the
list (as we would do if list_for_each_entry_reverse() was not a macro),
we would iterate backwards over the &exynos_drm_subdrv_list anchor,
which would be even worse.

Instead, we need to use list_for_each_entry_continue_reverse()
to go back over each subdrv that was successfully opened until
the first entry.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since atomic check is called also for disabled crtcs it should skip
mode checking as it can be uninitialized. The patch fixes it.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Exynos GEM objects contains an array of pointers to the pages, which the
allocated buffer consists of. Till now the code used some hacks (like
relying on DMA-mapping internal structures or using ARM-specific
dma_to_pfn helper) to build this array. This patch fixes this by adding
proper call to dma_get_sgtable_attrs() and using the acquired scatter-list
to construct needed array. This approach is more portable (work also for
ARM64) and finally fixes the layering violation that was present in this
code.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Many Exynos DRM sub-options mentions Exynos DRM in their titles.
It is redundant and can be safely shortened. The patch additionally
makes some entries more descriptive.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Exynos DRM driver have quite big number of components and options.
The patch re-arranges them into three logical groups:
- CRTCs,
- Encoders and Bridges,
- Sub-drivers.
It should make driver options more clear.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

All options depends on DRM_EXYNOS so it can be moved to enclosing if clause.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Latest Exynos SoCs does not have Mixer IP, but they still have HDMI IP.
Their drivers should be configurable separately.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

HDMI driver called directly function from MIXER driver to invalidate modes
not supported by MIXER. The patch replaces the hack with proper .atomic_check
callback.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

Some CRTCs needs mode validation, this patch adds neccessary
callback to Exynos DRM framework. It is called from DRM core
via atomic_check helper for drm_crtc.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

DECON-TV IP is responsible for generating video stream which is transferred
to HDMI IP. It is almost fully compatible with DECON IP.

The patch is based on initial work of Hyungwon Hwang.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>