Upstreaming DAL

[Alex Deucher]

Our goal is to transition to our new DAL display stack.  It is the
path we are validating internally for both the open and hybrid stacks
and will be the only display stack we support going forward with new
asics.  When we initially released the patches, there were some rough
edges and quite a few things were pointed out that need to be fixed.
Some are relatively easy to fix, others will take time.  Our goal is
to make those changes.  We'd like to target 4.7 for upstreaming DAL.
To that end, I think it would be easier to review and track our
progress if I maintained a public DAL branch and send out patches
against that branch rather than respinning giant squashed patches
every time we fix something.  It's much harder to track what progress
has been made.  DAL is currently at ~400 patches.  We previously tried
to squash that down into a bunch of larger commits, but I'm not sure
that is particularly easy to review.  I'm also not sure it's worth
spamming the list with 400 patches.  I've posted our current DAL tree
here for review:
https://cgit.freedesktop.org/~agd5f/linux/log/?h=drm-next-4.7-wip-dal
I can certainly send out the patches if that is preferred.  We will be
sending out all new patches to the list as the further clean up tasks
and new features are implemented.

Our goal is to fix the following items in time for 4.7.  Additional
fixes and re-factoring will continue as we work to address all of the
comments and concerns.

Tasks to be completed for 4.7:
- Remove (malloc/free/sleep/delay/etc.) wrappers for building DAL in
userspace (done)
- Switch to using Linux i2c subsystem (done)
- Switch to using Linux drm aux interface (in progress)
- Convert cursors to planes API (in progress)
- Switch to native drm EDID fetching (in progress)

Tasks post 4.7 (we will attempt to fix these sooner as time permits):
- Using common Linux infoframe infrastructure
- Migrating to common logging infrastructure
- Refactoring DC

Current DAL status:
- DCE8 Support (Hawaii, Bonaire)
- DCE10 Support (Fiji, Tonga)
- DCE11 Support (CZ, ST)
- DP support (SST, MST, Audio)
- HDMI Support
- HDMI 2.0 Support (on supported asics)
- DVI Support
- Full integration with power management
- Atomic KMS support
- Solid 4K at 60 Support

Thanks,

Alex