drm: Rename dp/ to display/

Rename dp/ to display/ to account for additional display-related
helpers, such as HDMI. Update all related include statements. No
functional changes.

Various drivers, such as i915 and amdgpu, use similar naming scheme
by putting code for video-output standards into a local display/
directory. The new directory's name is aligned with this convention.

v2:
* update commit message (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220421073108.19226-3-tzimmermann@suse.de

drm/dp: Fix OOB read when handling Post Cursor2 register

The link_status array was not large enough to read the Adjust Request
Post Cursor2 register, so remove the common helper function to avoid
an OOB read, found with a -Warray-bounds build:

drivers/gpu/drm/drm_dp_helper.c: In function 'drm_dp_get_adjust_request_post_cursor':
drivers/gpu/drm/drm_dp_helper.c:59:27: error: array subscript 10 is outside array bounds of 'const u8[6]' {aka 'const unsigned char[6]'} [-Werror=array-bounds]
59 | return link_status[r - DP_LANE0_1_STATUS];
| ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/drm_dp_helper.c:147:51: note: while referencing 'link_status'
147 | u8 drm_dp_get_adjust_request_post_cursor(const u8 link_status[DP_LINK_STATUS_SIZE],
| ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Replace the only user of the helper with an open-coded fetch and decode,
similar to drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c.

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Fixes: 79465e0ffeb9 ("drm/dp: Add helper to get post-cursor adjustments")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20220105173507.2420910-1-keescook@chromium.org
Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/dp: Move public DisplayPort headers into dp/

Move all public DisplayPort headers into dp/ and update users. No
functional changes.

v3:
* rebased onto latest drm-tip

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220114114535.29157-5-tzimmermann@suse.de

drm/tegra: sor: Add DisplayPort support

Add support for regular DisplayPort on Tegra210 and Tegra186.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Add DisplayPort link training helper

Add a helper that will perform link training as described in the
DisplayPort specification.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Add support for eDP link rates

Parses additional link rates from DPCD if the sink supports eDP 1.4.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Add drm_dp_link_choose() helper

This helper chooses an appropriate configuration, according to the
bitrate requirements of the video mode and the capabilities of the
DisplayPort sink.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Enable alternate scrambler reset when supported

If the sink is eDP and supports the alternate scrambler reset, enable
it.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Set channel coding on link configuration

Make use of ANSI 8B/10B channel coding if the DisplayPort sink supports
it.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read AUX read interval from DPCD

Store the AUX read interval from DPCD, so that it can be used to wait
for the durations given in the specification during link training.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read eDP version from DPCD

If the sink supports eDP, read the eDP revision from it's DPCD.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read alternate scrambler reset capability from sink

Parse from the sink capabilities whether or not the eDP alternate
scrambler reset value of 0xfffe is supported.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read channel coding capability from sink

Parse from the sink capabilities whether or not it supports ANSI 8B/10B
channel coding as specified in ANSI X3.230-1994, clause 11.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read TPS3 capability from sink

The TPS3 capability can be exposed by DP 1.2 and later sinks if they
support the alternative training pattern for channel equalization.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Read fast training capability from link

While probing the DisplayPort link, query the fast training capability.
If supported, drivers can use the fast link training sequence instead of
the more involved full link training sequence.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Probe link using existing parsing helpers

Use existing parsing helpers to probe a DisplayPort link.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Turn link capabilities into booleans

Rather than storing capabilities as flags in an integer, use a separate
boolean per capability. This simplifies the code that checks for these
capabilities.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Track link capabilities alongside settings

Store capabilities in max_* fields and add separate fields for the
currently selected settings.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: dp: Add drm_dp_link_reset() implementation

Subsequent patches will add non-volatile fields to struct drm_dp_link,
so introduce a function to zero out only the volatile fields.

Signed-off-by: Thierry Reding <treding@nvidia.com>

drm/tegra: Move drm_dp_link helpers to Tegra DRM

During the discussion of patches that enhance the drm_dp_link helpers it
was concluded that these helpers aren't very useful to begin with. After
all other drivers have been converted not to use these helpers anymore,
move these helpers into the last remaining user: Tegra DRM.

If at some point these helpers are deemed more widely useful, they can
be moved out into the DRM DP helpers again.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20191021143437.1477719-14-thierry.reding@gmail.com