[Intel-gfx] [PATCH v4 00/17] Support for sustained capturing of GuC firmware logs

[akash.goel at intel.com]

From: Akash Goel <akash.goel at intel.com>

GuC firmware log its debug messages into a Host-GuC shared memory buffer
and when the buffer is half full it sends a Flush interrupt to Host.
GuC firmware follows the half-full draining protocol where it expects that
while it is writing to 2nd half of the buffer, first half would get consumed
by Host and then get a flush completed acknowledgement from Host, so that it
does not end up doing any overwrite causing loss of logs.
So far flush interrupt wasn't enabled on Host side & User could capture the
contents/snapshot of log buffer through 'i915_guc_log_dump' debugfs iface.
But this couldn't meet couple of key requirements, especially of Validation,
first is to ensure capturing of all boot time logs even with high verbosity
level and second is to enable capturing of logs in a sustained manner like
for the entire duration of a workload.
Now Driver will enable flush interrupt and on receving it, would copy the
contents of log buffer into its local buffer. The size of local buffer would
be big enough to contain multiple snapshots of the log buffer giving ample
time to User to pull boot time messages.
Have added a debugfs interface '/sys/kernel/debug/dri/guc_log' for User to
collect the logs. Availed relay framework to implement this interface, where
Driver will have to just use a relay API to store snapshots of GuC log buffer
in a buffer managed by relay. The relay buffer will be operated in a mode
where the old data, not yet collected by User, will be overwritten if buffer
becomes full. So the behavior exhibited will be equivalent to 'dmesg -c'.
Besides mmap method, through which User can directly access the relay
buffer contents, relay also supports the 'poll' method. Through the 'poll'
call on log file, User can come to know whenever a new snapshot of the log
buffer is taken by Driver, so can run in tandem with the Driver and thus
capture logs in a sustained/streaming manner, without any loss of data.

v2: Rebased to the latest drm-intel-nightly.

v3: Aligned with the modification of late debugfs registration, at the end of
    i915 Driver load. Did cleanup as per Tvrtko's review comments, added 3
    new patches to optimize the log-buffer flush interrupt handling, gather
    and report the logging related stats.

v4: Added 2 new patches to further optimize the log-buffer flush interrupt
    handling. Did cleanup as per Chris's review comments, fixed couple of
    issues related to clearing of Guc2Host message register. Switched to
    no-overwrite mode for the relay.

Akash Goel (10):
  drm/i915: New structure to contain GuC logging related fields
  drm/i915: Add low level set of routines for programming PM IER/IIR/IMR
    register set
  drm/i915: Add a relay backed debugfs interface for capturing GuC logs
  drm/i915: New module param to control the size of buffer used for
    storing GuC firmware logs
  drm/i915: Use uncached(WC) mapping for acessing the GuC log buffer
  drm/i915: New lock to serialize the Host2GuC actions
  drm/i915: Add stats for GuC log buffer flush interrupts
  drm/i915: Increase GuC log buffer size to reduce flush interrupts
  drm/i915: Optimization to reduce the sampling time of GuC log buffer
  drm/i915: Use rt priority kthread to do GuC log buffer sampling

Chris Wilson (1):
  drm/i915: Support to create write combined type vmaps

Sagar Arun Kamble (6):
  drm/i915: Decouple GuC log setup from verbosity parameter
  drm/i915: Add GuC ukernel logging related fields to fw interface file
  drm/i915: Support for GuC interrupts
  drm/i915: Handle log buffer flush interrupt event from GuC
  drm/i915: Forcefully flush GuC log buffer on reset
  drm/i915: Debugfs support for GuC logging control

 drivers/gpu/drm/i915/i915_debugfs.c        |  60 +++-
 drivers/gpu/drm/i915/i915_drv.c            |   2 +
 drivers/gpu/drm/i915/i915_drv.h            |   8 +-
 drivers/gpu/drm/i915/i915_gem.c            |  57 ++-
 drivers/gpu/drm/i915/i915_gem_dmabuf.c     |   2 +-
 drivers/gpu/drm/i915/i915_guc_submission.c | 554 ++++++++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_irq.c            | 159 +++++++--
 drivers/gpu/drm/i915/i915_params.c         |   5 +
 drivers/gpu/drm/i915/i915_params.h         |   1 +
 drivers/gpu/drm/i915/i915_reg.h            |  11 +
 drivers/gpu/drm/i915/intel_drv.h           |   6 +
 drivers/gpu/drm/i915/intel_guc.h           |  30 +-
 drivers/gpu/drm/i915/intel_guc_fwif.h      |  82 ++++-
 drivers/gpu/drm/i915/intel_guc_loader.c    |  12 +-
 drivers/gpu/drm/i915/intel_lrc.c           |   8 +-
 drivers/gpu/drm/i915/intel_ringbuffer.c    |   6 +-
 16 files changed, 934 insertions(+), 69 deletions(-)

-- 
1.9.2