1. 30 Apr, 2019 11 commits
  2. 29 Apr, 2019 1 commit
  3. 26 Apr, 2019 25 commits
  4. 25 Apr, 2019 2 commits
  5. 24 Apr, 2019 1 commit
    • Chris Wilson's avatar
      drm/i915: Invert the GEM wakeref hierarchy · 79ffac85
      Chris Wilson authored
      In the current scheme, on submitting a request we take a single global
      GEM wakeref, which trickles down to wake up all GT power domains. This
      is undesirable as we would like to be able to localise our power
      management to the available power domains and to remove the global GEM
      operations from the heart of the driver. (The intent there is to push
      global GEM decisions to the boundary as used by the GEM user interface.)
      
      Now during request construction, each request is responsible via its
      logical context to acquire a wakeref on each power domain it intends to
      utilize. Currently, each request takes a wakeref on the engine(s) and
      the engines themselves take a chipset wakeref. This gives us a
      transition on each engine which we can extend if we want to insert more
      powermangement control (such as soft rc6). The global GEM operations
      that currently require a struct_mutex are reduced to listening to pm
      events from the chipset GT wakeref. As we reduce the struct_mutex
      requirement, these listeners should evaporate.
      
      Perhaps the biggest immediate change is that this removes the
      struct_mutex requirement around GT power management, allowing us greater
      flexibility in request construction. Another important knock-on effect,
      is that by tracking engine usage, we can insert a switch back to the
      kernel context on that engine immediately, avoiding any extra delay or
      inserting global synchronisation barriers. This makes tracking when an
      engine and its associated contexts are idle much easier -- important for
      when we forgo our assumed execution ordering and need idle barriers to
      unpin used contexts. In the process, it means we remove a large chunk of
      code whose only purpose was to switch back to the kernel context.
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
      Cc: Imre Deak <imre.deak@intel.com>
      Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
      Link: https://patchwork.freedesktop.org/patch/msgid/20190424200717.1686-5-chris@chris-wilson.co.uk
      79ffac85