Merge tag 'drm-intel-next-2020-05-15' of git://anongit.freedesktop.org/drm/drm-intel into drm-next

UAPI Changes:

- drm/i915: Show per-engine default property values in sysfs

    By providing the default values configured into the kernel via sysfs, it
    is much more convenient for userspace to restore those sane defaults, or
    at least know what are considered good baseline. This is useful, for
    example, to cleanup after any failed userspace prior to commencing new
    jobs.

Cross-subsystem Changes:

- video/hdmi: Add Unpack only function for DRM infoframe
- Includes pull request gvt-next-2020-05-12

Driver Changes:

- Restore Cherryview back to full-ppgtt (Chris, Mika)
- Document locking guidelines for i915 (Chris, Daniel, Joonas)
- Fix GitLab #1746: Handle idling during i915_gem_evict_something busy loops (Chris)
- Display WA #1105: Require linear fb stride to be multiple of 512 bytes on
  gen9/glk (Ville)
- Add Wa_14010685332 for ICP/ICL (Matt R)
- Restrict w/a 1607087056 for EHL/JSL (Swathi)
- Fix interrupt handling for DP AUX transactions on Tigerlake (Imre)
- Revert "drm/i915/tgl: Include ro parts of l3 to invalidate" (Mika)
- Fix HDC pipeline flush hardware bit on Gen12 (Mika)
- Flush L3 when flushing render on Gen12 (Mika)
- Invalidate aux table entries forcibly between BB on Gen12 (Mika)
- Add aux table invalidate for all engines on Gen12 (Mika)
- Force pte cacheline to main memory Gen8+ (Mika)
- Add and enable TGL+ SAGV support (Stanislav)
- Implement vm_ops->access on i915 mmaps for GDB (Chris, Kristian)
- Replace zero-length array with flexible-array (Gustavo)
- Improve batch buffer pool effectiveness to mitigate soft-rc6 hit (Chris)
- Remove wait priority boosting (Chris)
- Keep driver module referenced when PMU is active (Chris)
- Sanitize RPS interrupts upon resume (Chris)
- Extend pcode read timeout to 20 ms (Chris)
- Wait for ACT sent before enabling MST pipe (Ville)
- Extend support to async relocations to SNB (Chris)
- Remove CNL pre-prod workarounds (Ville)
- Don't enable WaIncreaseLatencyIPCEnabled when IPC is disabled (Sultan)
- Record the active CCID from before reset (Chris)
- Mark concurrent submissions with a weak-dependency (Chris)
- Peel dma-fence-chains for await to allow engine-to-engine sync (Lionel)
- Prevent using semaphores to chain up to external fences (Chris)
- Fix GLK watermark calculations (Ville)
- Emit await(batch) before MI_BB_START (Chris)
- Reset execlists registers before HWSP (Chris)
- Drop no-semaphore boosting in favor of fast timeslicing (Chris)
- Fix enabled infoframe states of lspcon (Gwan-gyeong)
- Program DP SDPs on pipe updates (Gwan-gyeong)
- Stop sending DP SDPs on ddi disable (Gwan-gyeong)
- Store CS timestamp frequency in Hz (Ville)

- Remove unused HAS_FWTABLE macro (Pascal)
- Use batchbuffer chaining for relocations to save ring space (Chris)
- Try different engines for relocs if MI ops not supported (Chris, Tvrtko)
- Lazily acquire the device wakeref for freeing objects (Chris)
- Streamline display code arithmetics around rounding etc. (Ville)
- Use bw state for per crtc SAGV evaluation (Stanislav)
- Track active_pipes in bw_state (Stanislav)
- Nuke mode.vrefresh usage (Ville)
- Warn if the FBC is still writing to stolen on removal (Chris)
- Added new PCode commands prepping for QGV rescricting (Stansilav)
- Stop holding onto the pinned_default_state (Chris)
- Propagate error from completed fences (Chris)
- Ignore submit-fences on the same timeline (Chris)
- Pull waiting on an external dma-fence into its routine (Chris)
- Replace the hardcoded I915_FENCE_TIMEOUT with Kconfig (Chris)
- Mark up the racy read of execlists->context_tag (Chris)
- Tidy up the return handling for completed dma-fences (Chris)
- Introduce skl_plane_wm_level accessor (Stanislav)
- Extract SKL SAGV checking (Stanislav)
- Make active_pipes check skl specific (Stanislav)
- Suspend tasklets before resume sanitization (Chris)
- Remove redundant exec_fence (Chris)
- Mark the addition of the initial-breadcrumb in the request (Chris)
- Transfer old virtual breadcrumbs to irq_worker (Chris)
- Read the DP SDPs from the video DIP (Gwan-gyeong)
- Program DP SDPs with computed configs (Gwan-gyeong)
- Add state readout for DP VSC and DP HDR Metadata Infoframe SDP
  (Gwan-gyeong)
- Add compute routine for DP PSR VSC SDP (Gwan-gyeong)
- Use new DP VSC SDP compute routine on PSR (Gwan-gyeong)
- Restrict qgv points which don't have enough bandwidth. (Stanislav)
- Nuke pointless div by 64bit (Ville)

- Static checker code fixes (Nathan, Mika, Chris)
- Add logging function for DP VSC SDP (Gwan-gyeong)
- Include HDMI DRM infoframe, DP HDR metadata and DP VSC SDP in the
  crtc state dump (Gwan-gyeong)
- Make timeslicing explicit engine property (Chris, Tvrtko)
- Selftest and debugging improvements (Chris)
- Align variable names with BSpec (Ville)
- Tidy up gen8+ breadcrumb emission code (Chris)
- Turn intel_digital_port_connected() in a vfunc (Ville)
- Use stashed away hpd isr bits in intel_digital_port_connected() (Ville)
- Extract i915_cs_timestamp_{ns_to_ticks,tick_to_ns}() (Ville)

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200515160703.GA19043@jlahtine-desk.ger.corp.intel.com

1 files changed, 46 insertions, 0 deletions

diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
index 429b08aac797..33cc6ddf8f64 100644
--- a/Documentation/gpu/i915.rst
+++ b/Documentation/gpu/i915.rst
@@ -329,6 +329,52 @@ for execution also include a list of all locations within buffers that
 refer to GPU-addresses so that the kernel can edit the buffer correctly.
 This process is dubbed relocation.
 
+Locking Guidelines
+------------------
+
+.. note::
+   This is a description of how the locking should be after
+   refactoring is done. Does not necessarily reflect what the locking
+   looks like while WIP.
+
+#. All locking rules and interface contracts with cross-driver interfaces
+   (dma-buf, dma_fence) need to be followed.
+
+#. No struct_mutex anywhere in the code
+
+#. dma_resv will be the outermost lock (when needed) and ww_acquire_ctx
+   is to be hoisted at highest level and passed down within i915_gem_ctx
+   in the call chain
+
+#. While holding lru/memory manager (buddy, drm_mm, whatever) locks
+   system memory allocations are not allowed
+
+	* Enforce this by priming lockdep (with fs_reclaim). If we
+	  allocate memory while holding these looks we get a rehash
+	  of the shrinker vs. struct_mutex saga, and that would be
+	  real bad.
+
+#. Do not nest different lru/memory manager locks within each other.
+   Take them in turn to update memory allocations, relying on the object’s
+   dma_resv ww_mutex to serialize against other operations.
+
+#. The suggestion for lru/memory managers locks is that they are small
+   enough to be spinlocks.
+
+#. All features need to come with exhaustive kernel selftests and/or
+   IGT tests when appropriate
+
+#. All LMEM uAPI paths need to be fully restartable (_interruptible()
+   for all locks/waits/sleeps)
+
+	* Error handling validation through signal injection.
+	  Still the best strategy we have for validating GEM uAPI
+          corner cases.
+	  Must be excessively used in the IGT, and we need to check
+	  that we really have full path coverage of all error cases.
+
+	* -EDEADLK handling with ww_mutex
+
 GEM BO Management Implementation Details
 ----------------------------------------