1. 14 Aug, 2014 10 commits
    • Oscar Mateo's avatar
      drm/i915/bdw: Avoid non-lite-restore preemptions · e1fee72c
      Oscar Mateo authored
      In the current Execlists feeding mechanism, full preemption is not
      supported yet: only lite-restores are allowed (this is: the GPU
      simply samples a new tail pointer for the context currently in
      execution).
      
      But we have identified an scenario in which a full preemption occurs:
      1) We submit two contexts for execution (A & B).
      2) The GPU finishes with the first one (A), switches to the second one
      (B) and informs us.
      3) We submit B again (hoping to cause a lite restore) together with C,
      but in the time we spend writing to the ELSP, the GPU finishes B.
      4) The GPU start executing B again (since we told it so).
      5) We receive a B finished interrupt and, mistakenly, we submit C (again)
      and D, causing a full preemption of B.
      
      The race is avoided by keeping track of how many times a context has been
      submitted to the hardware and by better discriminating the received context
      switch interrupts: in the example, when we have submitted B twice, we won´t
      submit C and D as soon as we receive the notification that B is completed
      because we were expecting to get a LITE_RESTORE and we didn´t, so we know a
      second completion will be received shortly.
      
      Without this explicit checking, somehow, the batch buffer execution order
      gets messed with. This can be verified with the IGT test I sent together with
      the series. I don´t know the exact mechanism by which the pre-emption messes
      with the execution order but, since other people is working on the Scheduler
      + Preemption on Execlists, I didn´t try to fix it. In these series, only Lite
      Restores are supported (other kind of preemptions WARN).
      
      v2: elsp_submitted belongs in the new intel_ctx_submit_request. Several
      rebase changes.
      
      v3: Clarify how the race is avoided, as requested by Daniel.
      Signed-off-by: default avatarOscar Mateo <oscar.mateo@intel.com>
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      [danvet: Align function parameters ...]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      e1fee72c
    • Thomas Daniel's avatar
      drm/i915/bdw: Handle context switch events · e981e7b1
      Thomas Daniel authored
      Handle all context status events in the context status buffer on every
      context switch interrupt. We only remove work from the execlist queue
      after a context status buffer reports that it has completed and we only
      attempt to schedule new contexts on interrupt when a previously submitted
      context completes (unless no contexts are queued, which means the GPU is
      free).
      
      We canot call intel_runtime_pm_get() in an interrupt (or with a spinlock
      grabbed, FWIW), because it might sleep, which is not a nice thing to do.
      Instead, do the runtime_pm get/put together with the create/destroy request,
      and handle the forcewake get/put directly.
      Signed-off-by: default avatarThomas Daniel <thomas.daniel@intel.com>
      
      v2: Unreferencing the context when we are freeing the request might free
      the backing bo, which requires the struct_mutex to be grabbed, so defer
      unreferencing and freeing to a bottom half.
      
      v3:
      - Ack the interrupt inmediately, before trying to handle it (fix for
      missing interrupts by Bob Beckett <robert.beckett@intel.com>).
      - Update the Context Status Buffer Read Pointer, just in case (spotted
      by Damien Lespiau).
      
      v4: New namespace and multiple rebase changes.
      
      v5: Squash with "drm/i915/bdw: Do not call intel_runtime_pm_get() in an
      interrupt", as suggested by Daniel.
      Signed-off-by: default avatarOscar Mateo <oscar.mateo@intel.com>
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      [danvet: Checkpatch ...]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      e981e7b1
    • Michel Thierry's avatar
      drm/i915/bdw: Two-stage execlist submit process · acdd884a
      Michel Thierry authored
      Context switch (and execlist submission) should happen only when
      other contexts are not active, otherwise pre-emption occurs.
      
      To assure this, we place context switch requests in a queue and those
      request are later consumed when the right context switch interrupt is
      received (still TODO).
      
      v2: Use a spinlock, do not remove the requests on unqueue (wait for
      context switch completion).
      Signed-off-by: default avatarThomas Daniel <thomas.daniel@intel.com>
      
      v3: Several rebases and code changes. Use unique ID.
      
      v4:
      - Move the queue/lock init to the late ring initialization.
      - Damien's kmalloc review comments: check return, use sizeof(*req),
      do not cast.
      
      v5:
      - Do not reuse drm_i915_gem_request. Instead, create our own.
      - New namespace.
      
      Signed-off-by: Michel Thierry <michel.thierry@intel.com> (v1)
      Signed-off-by: Oscar Mateo <oscar.mateo@intel.com> (v2-v5)
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      [davnet: Checkpatch + wash-up s/BUG_ON/WARN_ON/.]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      acdd884a
    • Oscar Mateo's avatar
      drm/i915/bdw: Write the tail pointer, LRC style · ae1250b9
      Oscar Mateo authored
      Each logical ring context has the tail pointer in the context object,
      so update it before submission.
      
      v2: New namespace.
      Signed-off-by: default avatarOscar Mateo <oscar.mateo@intel.com>
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      ae1250b9
    • Ben Widawsky's avatar
      drm/i915/bdw: Implement context switching (somewhat) · 84b790f8
      Ben Widawsky authored
      A context switch occurs by submitting a context descriptor to the
      ExecList Submission Port. Given that we can now initialize a context,
      it's possible to begin implementing the context switch by creating the
      descriptor and submitting it to ELSP (actually two, since the ELSP
      has two ports).
      
      The context object must be mapped in the GGTT, which means it must exist
      in the 0-4GB graphics VA range.
      Signed-off-by: default avatarBen Widawsky <ben@bwidawsk.net>
      
      v2: This code has changed quite a lot in various rebases. Of particular
      importance is that now we use the globally unique Submission ID to send
      to the hardware. Also, context pages are now pinned unconditionally to
      GGTT, so there is no need to bind them.
      
      v3: Use LRCA[31:12] as hwCtxId[19:0]. This guarantees that the HW context
      ID we submit to the ELSP is globally unique and != 0 (Bspec requirements
      of the software use-only bits of the Context ID in the Context Descriptor
      Format) without the hassle of the previous submission Id construction.
      Also, re-add the ELSP porting read (it was dropped somewhere during the
      rebases).
      
      v4:
      - Squash with "drm/i915/bdw: Add forcewake lock around ELSP writes" (BSPEC
        says: "SW must set Force Wakeup bit to prevent GT from entering C6 while
        ELSP writes are in progress") as noted by Thomas Daniel
        (thomas.daniel@intel.com).
      - Rename functions and use an execlists/intel_execlists_ namespace.
      - The BUG_ON only checked that the LRCA was <32 bits, but it didn't make
        sure that it was properly aligned. Spotted by Alistair Mcaulay
        <alistair.mcaulay@intel.com>.
      
      v5:
      - Improved source code comments as suggested by Chris Wilson.
      - No need to abstract submit_ctx away, as pointed by Brad Volkin.
      Signed-off-by: default avatarOscar Mateo <oscar.mateo@intel.com>
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      [danvet: Checkpatch. Sigh.]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      84b790f8
    • Oscar Mateo's avatar
      drm/i915/bdw: Emission of requests with logical rings · 48e29f55
      Oscar Mateo authored
      On a previous iteration of this patch, I created an Execlists
      version of __i915_add_request and asbtracted it away as a
      vfunc. Daniel Vetter wondered then why that was needed:
      
      "with the clean split in command submission I expect every
      function to know wether it'll submit to an lrc (everything in
      intel_lrc.c) or wether it'll submit to a legacy ring (existing
      code), so I don't see a need for an add_request vfunc."
      
      The honest, hairy truth is that this patch is the glue keeping
      the whole logical ring puzzle together:
      
      - i915_add_request is used by intel_ring_idle, which in turn is
        used by i915_gpu_idle, which in turn is used in several places
        inside the eviction and gtt codes.
      - Also, it is used by i915_gem_check_olr, which is littered all
        over i915_gem.c
      - ...
      
      If I were to duplicate all the code that directly or indirectly
      uses __i915_add_request, I'll end up creating a separate driver.
      
      To show the differences between the existing legacy version and
      the new Execlists one, this time I have special-cased
      __i915_add_request instead of adding an add_request vfunc. I
      hope this helps to untangle this Gordian knot.
      Signed-off-by: default avatarOscar Mateo <oscar.mateo@intel.com>
      Reviewed-by: default avatarDamien Lespiau <damien.lespiau@intel.com>
      [danvet: Adjust to ringbuf->FIXME_lrc_ctx per the discussion with
      Thomas Daniel.]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      48e29f55
    • Oscar Mateo's avatar
      drm/i915: Add temporary ring->ctx backpointer · 582d67f0
      Oscar Mateo authored
      The execlist patches have a bit a convoluted and long history and due
      to that have the actual submission still misplaced deeply burried in
      the low-level ringbuffer handling code. This design goes back to the
      legacy ringbuffer code with its tricky lazy request and simple work
      submissiion using ring tail writes. For that reason they need a
      ring->ctx backpointer.
      
      The goal is to unburry that code and move it up into a level where the
      full execlist context is available so that we can ditch this
      backpointer. Until that's done make it really obvious that there's
      work still to be done.
      
      Cc: Oscar Mateo <oscar.mateo@intel.com>
      Cc: Thomas Daniel <thomas.daniel@intel.com>
      Acked-by: default avatarThomas Daniel <thomas.daniel@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      582d67f0
    • Chris Wilson's avatar
      drm/i915: Print captured bo for all VM in error state · 3a448734
      Chris Wilson authored
      The current error state harks back to the era of just a single VM. For
      full-ppgtt, we capture every bo on every VM. It behoves us to then print
      every bo for every VM, which we currently fail to do and so miss vital
      information in the error state.
      
      v2: Use the vma address rather than -1!
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Reviewed-by: default avatarMika Kuoppala <mika.kuoppala@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      3a448734
    • Sagar Kamble's avatar
      drm/i915: Sharing platform specific sequence between runtime and system suspend/ resume paths · 016970be
      Sagar Kamble authored
      On VLV, post S0i3 during i915_drm_thaw following issue is observed during ring
      initialization.
      
      [ 335.604039] [drm:stop_ring] ERROR render ring :timed out trying to stop ring
      [ 336.607340] [drm:stop_ring] ERROR render ring :timed out trying to stop ring
      [ 336.607345] [drm:init_ring_common] ERROR failed to set render ring head to zero ctl 00000000 head 00000000 tail 00000000 start 00000000
      [ 337.610645] [drm:stop_ring] ERROR bsd ring :timed out trying to stop ring
      [ 338.613952] [drm:stop_ring] ERROR bsd ring :timed out trying to stop ring
      [ 338.613956] [drm:init_ring_common] ERROR failed to set bsd ring head to zero ctl 00000000 head 00000000 tail 00000000 start 00000000
      [ 339.617256] [drm:stop_ring] ERROR render ring :timed out trying to stop ring
      [ 339.617258] -----------[ cut here ]-----------
      [ 339.617267] WARNING: CPU: 0 PID: 6 at drivers/gpu/drm/i915/intel_ringbuffer.c:1666 intel_cleanup_ring+0xe6/0xf0()
      [ 339.617396] --[ end trace 5ef5ed1a3c92e2a6 ]--
      [ 339.617428] [drm:__i915_drm_thaw] ERROR failed to re-initialize GPU, declaring wedged!
      
      This is happening since wake is not enabled and Gunit registers are not restored.
      For this system suspend/resume paths need to follow save/restore and additional
      platform specific setup in suspend_complete and resume_prepare.
      
      suspend_complete is shared unconditionaly for VLV, HSW, BDW. resume_prepare for
      HSW and BDW has pc8 disabling which is needed during thaw_early so sharing
      uncondtionally. For VLV and SNB runtime resume specific sequence exists.
      
      Cc: Imre Deak <imre.deak@intel.com>
      Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Cc: Jani Nikula <jani.nikula@linux.intel.com>
      Cc: Goel, Akash <akash.goel@intel.com>
      Signed-off-by: default avatarSagar Kamble <sagar.a.kamble@intel.com>
      Reviewed-by: default avatarImre Deak <imre.deak@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      016970be
    • Sagar Kamble's avatar
      drm/i915: Created common handler for platform specific suspend/resume · ebc32824
      Sagar Kamble authored
      With this change, intel_runtime_suspend and intel_runtime_resume functions
      become completely platform agnostic. Platform specific suspend/resume
      changes are moved to intel_suspend_complete and intel_resume_prepare.
      
      Cc: Imre Deak <imre.deak@intel.com>
      Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Cc: Jani Nikula <jani.nikula@linux.intel.com>
      Cc: Goel, Akash <akash.goel@intel.com>
      Signed-off-by: default avatarSagar Kamble <sagar.a.kamble@intel.com>
      Reviewed-by: default avatarImre Deak <imre.deak@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      ebc32824
  2. 13 Aug, 2014 18 commits
  3. 12 Aug, 2014 2 commits
    • Daniel Vetter's avatar
      drm/i915: Some cleanups for the ppgtt lifetime handling · ee960be7
      Daniel Vetter authored
      So when reviewing Michel's patch I've noticed a few things and cleaned
      them up:
      - The early checks in ppgtt_release are now redundant: The inactive
        list should always be empty now, so we can ditch these checks. Even
        for the aliasing ppgtt (though that's a different confusion) since
        we tear that down after all the objects are gone.
      - The ppgtt handling functions are splattered all over. Consolidate
        them in i915_gem_gtt.c, give them OCD prefixes and add wrappers for
        get/put.
      - There was a bit a confusion in ppgtt_release about whether it cares
        about the active or inactive list. It should care about them both,
        so augment the WARNINGs to check for both.
      
      There's still create_vm_for_ctx left to do, put that is blocked on the
      removal of ppgtt->ctx. Once that's done we can rename it to
      i915_ppgtt_create and move it to its siblings for handling ppgtts.
      
      v2: Move the ppgtt checks into the inline get/put functions as
      suggested by Chris.
      
      v3: Inline the now redundant ppgtt local variable.
      
      Cc: Michel Thierry <michel.thierry@intel.com>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Reviewed-by: default avatarMichel Thierry <michel.thierry@intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      ee960be7
    • Michel Thierry's avatar
      drm/i915: vma/ppgtt lifetime rules · b9d06dd9
      Michel Thierry authored
      VMAs should take a reference of the address space they use.
      
      Now, when the fd is closed, it will release the ref that the context was
      holding, but it will still be referenced by any vmas that are still
      active.
      
      ppgtt_release() should then only be called when the last thing referencing
      it releases the ref, and it can just call the base cleanup and free the
      ppgtt.
      
      Note that with this we will extend the lifetime of ppgtts which
      contain shared objects. But all the non-shared objects will get
      removed as soon as they drop of the active list and for the shared
      ones the shrinker can eventually reap them. Since we currently can't
      evict ppgtt pagetables either I don't think that temporary leak is
      important.
      Signed-off-by: default avatarMichel Thierry <michel.thierry@intel.com>
      [danvet: Add note about potential ppgtt leak with this approach.]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      b9d06dd9
  4. 11 Aug, 2014 10 commits