1. 14 Nov, 2014 22 commits
  2. 12 Nov, 2014 1 commit
  3. 10 Nov, 2014 2 commits
  4. 09 Nov, 2014 1 commit
    • Dave Airlie's avatar
      Merge tag 'topic/atomic-helpers-2014-11-09' of... · 122387a5
      Dave Airlie authored
      Merge tag 'topic/atomic-helpers-2014-11-09' of git://anongit.freedesktop.org/drm-intel into drm-next
      
      So here's my atomic series, finally all debugged&reviewed. Sean Paul has
      done a full detailed pass over it all, and a lot of other people have
      commented and provided feedback on some parts. Rob Clark also converted
      msm over the w/e and seems happy. The only small thing is that Rob wants
      to export the wait_for_vblank, which imo makes sense. Since there's other
      stuff still to do I think we should apply Rob's patch (once it has grown
      appropriate kerneldoc) later on top of this.
      
      This is just the core<->driver interface plus a big pile of helpers. Short
      recap of the main ideas:
      
      - There are essentially three helper libraries in this patch set:
      
        * Transitional helpers to use the new plane callbacks for legacy plane
          updates and in the crtc helper's ->mode_set callback. These helpers are
          only temporarily used to convert drivers to atomic, but they allow a
          nice separation between changing the driver backend and switching to
          the atomic commit logic.
      
        * Legacy helpers to implement all the legacy driver entry points
          (page_flip, set_config, plane vfuncs) on top of the new atomic driver
          interface. These are completely driver agnostic. The reason for having
          the legacy support as helpers is that drivers can switch step-by-step.
          And they could e.g. even keep the legacy page_flip code around for some
          old platforms where converting to full-blown atomic isn't worth it.
      
        * Atomic helpers which implement the various new ->atomic_* driver
          interfaces in terms of the revised crtc helper and new plane helper
          hooks.
      
      - The revised crtc helper implemenation essentially implements all the
        lessons learned in the i915 modeset rework (when using the atomic helpers
        only):
      
        * Enable/disable sequence for a given config are always the same and
          callbacks are always called in the same order. This contrast starkly
          with the crtc helpers, where the sequence of operations is heavily
          dependent on the previous config.
      
          One corollary of this is that if the configuration of a crtc only
          partially changes (e.g. a connector moves in a cloned config) the
          helper code will still disable/enable the full display pipeline. This
          is the only way to ensure that the enable/disable sequence is always
          the same.
      
        * It won't call disable or enable hooks more than once any more because
          it lost track of state, thanks to the atomic state tracking. And if
          drivers implement the ->reset hook properly (by either resetting the hw
          or reading out the hw state into the atomic structures) this even
          extends to the hardware state. So no more disable-me-harder kind of
          nonsense.
      
        * The only thing missing is the hw state readout/cross-check support, but
          if drivers have hw state readout support in their ->reset handlers it's
          simple to extend that to cross-check the hw state.
      
        * The crtc->mode_set callback is gone and its replacement only sets crtc
          timings and no longer updates the primary plane state. This way we can
          finally implement primary planes properly.
      
      - The new plane helpers should be suitable enough for pretty much
        everything, and a perfect fit for hardware with GO bits. Even if they
        don't fit the atomic helper library is rather flexible and exports all
        the functions for the individual steps to drivers. So drivers can pick
        what matches and implement their own magic for everything else.
      
      - A big difference compared to all previous atomic series is that this one
        doesn't implement async commit in a generic way. Imo driver requirements
        for that are too diverse to create anything reasonable sane which would
        actually work on a reasonable amount of different drivers. Also, we've
        never had a helper library for page_flips even, so it's really hard to
        know what might work and what's stupid without a bit of experience in the form
        of a few driver implementations.
      
        I think with the current flexibility for drivers to pick individual
        stages and existing helpers like drm_flip_queue it's rather easy though
        to implement proper async commit.
      
      - There's a few other differences of minor importance to earlier atomic
        series:
      
        * Common/generic properties are parsed in the callers/core and not in
          drivers, and passed to drivers by directly setting the right members in
          atomic state structures. That greatly simplifies all the transitional
          and legacy helpers an removes a lot of boilerplate code.
      
        * There's no crazy trylock mode used for the async commit since these
          helpers don't do async commit. A simple ordered flip queue of atomic
          state updates should be sufficient for preventing concurrent hw access
          anyway, as long as synchronous updates stall correctly with e.g.
          flush_work_queue or similar function. Abusing locks to enforce ordering
          isn't a good idea imo anyway.
      
        * These helpers reuse the existing ->mode_fixup hooks in the atomic_check
          callback. Which means that drivers need to adapat and move a lot less code
          into their atomic_check callbacks.
      
      Now this isn't everything needed in the drm core and helpers for full
      atomic support. But it's enough to start with converting drivers, and
      except for actually testing multiplane and multicrtc updates also enough to
      implement full atomic updates. Still missing are:
      
      - Per-plane locking. Since these helpers here encapsulate the locking
        completely this should be fairly easy to implement.
      
      - fbdev support for atomic_check/commit, so that multi-pipe finally works
        sanely in fbcon.
      
      - Adding and decoding shared/core properties. That just needs to be rebased
        from Rob's latest patch series, with minor adjustments so that the
        decoding happens in the core instead of in drivers.
      
      - Actually adding the atomic ioctl. Again just rebasing Rob's latest patch
        should be all that's needed.
      
      - Resolving how to deal with DPMS in atomic. Atomic is a good excuse to fix up
        the crazy semantics dpms currently has. I'm floating an RFC about this topic
        already.
      
      - Finally I couldn't test connector/encoder stealing properly since my test
        vehicle here doesn't allow a connector on different crtcs. So drivers
        which support this might see some surprises in that area. There is no semantic
        change though in how encoder stealing and assignment works (or at least no
        intended one), so I think the risk is minimal.
      
      As just mentioned I've done a fake conversion of an existing driver using
      crtc helpers to debug the helper code and validate the smooth transition
      approach. And that smooth transition was the really big motivation for
      this. It seems to actually work and consists of 3 phases:
      
      Phase 1: Rework driver backend for crtc/plane helpers
      
      The requirement here is that universal plane support is already implement. If
      universal plane support isn't implement yet it might be better though to just do
      it as part of this phase, directly using the new plane helpers. There are two
      big things to do:
      
      - Split up the existing ->update/disable_plane hooks into check/commit
        hooks and extract the crtc-wide prep/flush parts (like setting/clearing
        GO bits).
      
      - The other big change is to split the crtc->mode_set hook into the plane
        update (done using the plane helpers) and the crtc setup in a new
        ->mode_set_nofb hook.
      
      When phase 1 is complete the driver implements all the new callbacks which
      push the software state into hardware, but still using all the legacy entry
      points and crtc helpers. The transitional helpers serve as impendance
      mismatch here.
      
      Phase 2: Rework state handling
      
      This consists of rolling out the state handling helpers for planes, crtcs
      and connectors and reviewing all ->mode_fixup and similar hooks to make
      sure they don't depend upon implicit global state which might change in the
      atomic world. Any such code must be moved into ->atomic_check functions which
      just rely on the free-standing atomic state update structures.
      
      This phase also adds a few small pieces of fixup code to make sure the
      atomic state doesn't get out of sync in the legacy driver callbacks.
      
      Phase 3: Roll out atomic support
      
      Now it's just about replacing vfuncs with the ones provided by the helper
      and filling out the small missing pieces (like atomic_check logic or async
      commit support needed for page_flips). Due to the prep work in phase 1 no
      changes to the driver backend functions should be required, and because of
      the prep work in phase 2 atomic implementations can be rolled out
      step-by-step. So if async commit ins't implemented yet page_flip can be
      implemented with the legacy functions without wreaking havoc in the other
      operations.
      
      * tag 'topic/atomic-helpers-2014-11-09' of git://anongit.freedesktop.org/drm-intel:
        drm/atomic: Refcounting for plane_state->fb
        drm: Docbook integration and over sections for all the new helpers
        drm/atomic-helpers: functions for state duplicate/destroy/reset
        drm/atomic-helper: implement ->page_flip
        drm/atomic-helpers: document how to implement async commit
        drm/atomic: Integrate fence support
        drm/atomic-helper: implementatations for legacy interfaces
        drm: Atomic crtc/connector updates using crtc/plane helper interfaces
        drm/crtc-helper: Transitional functions using atomic plane helpers
        drm/plane-helper: transitional atomic plane helpers
        drm: Add atomic/plane helpers
        drm: Global atomic state handling
        drm: Add atomic driver interface definitions for objects
        drm/modeset_lock: document trylock_only in kerneldoc
        drm: fixup kerneldoc in drm_crtc.h
        drm: Pull drm_crtc.h into the kerneldoc template
        drm: Move drm_crtc_init from drm_crtc.h to drm_plane_helper.h
      122387a5
  5. 07 Nov, 2014 14 commits