drm/i915: Try to use fast+narrow link on eDP again and fall back to the old max strat...

drm/i915: Try to use fast+narrow link on eDP again and fall back to the old max strategy on failure

Some new eDP panels don't like to operate at the max parameters, and
instead we need to go for an optimal confiugration. That unfortunately
doesn't work with older eDP panels which are generally only guaranteed
to work at the max parameters.

To solve these two conflicting requirements let's start with the optimal
setup, and if that fails we start again with the max parameters. The
downside is probably an extra modeset when we switch strategies but
I don't see a good way to avoid that.

For a bit of history we first tried to go for the fast+narrow in
commit 4962b41f1ce3 ("drm/i915/dp: optimize eDP 1.4+ link config
fast and narrow"). but that had to be reverted due to regression
on older panels in commit 86beaa4910da ("drm/i915/dp: revert back
to max link rate and lane count on eDP"). So now we try to get
the best of both worlds by using both strategies.

v2: Deal with output_bpp and uapi vs. hw state split
    Reword some comments
v3: Rebase

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Albert Astals Cid <aacid@kde.org> # v5.0 backport
Cc: Emanuele Panigati <ilpanich@gmail.com> # v5.0 backport
Cc: Matteo Iervasi <matteoiervasi@gmail.com> # v5.0 backport
Cc: Timo Aaltonen <tjaalton@ubuntu.com>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=105267
References: https://bugs.freedesktop.org/show_bug.cgi?id=109959
References: https://gitlab.freedesktop.org/drm/intel/issues/272
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210107182026.24848-1-ville.syrjala@linux.intel.com