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[v3,0/7] drm/i915: Use the memcpy_from_wc function from drm

Message ID 20220426165148.1784-1-balasubramani.vivekanandan@intel.com (mailing list archive)
Headers show
Series drm/i915: Use the memcpy_from_wc function from drm | expand

Message

Vivekanandan, Balasubramani April 26, 2022, 4:51 p.m. UTC 
drm_memcpy_from_wc() performs fast copy from WC memory type using
non-temporal instructions. Now there are two similar implementations of
this function. One exists in drm_cache.c as drm_memcpy_from_wc() and
another implementation in i915/i915_memcpy.c as i915_memcpy_from_wc().
drm_memcpy_from_wc() was the recent addition through the series
https://patchwork.freedesktop.org/patch/436276/?series=90681&rev=6

The goal of this patch series is to change all users of
i915_memcpy_from_wc() to drm_memcpy_from_wc() and a have common
implementation in drm and eventually remove the copy from i915.

Another benefit of using memcpy functions from drm is that
drm_memcpy_from_wc() is available for non-x86 architectures.
i915_memcpy_from_wc() is implemented only for x86 and prevents building
i915 for ARM64.
drm_memcpy_from_wc() does fast copy using non-temporal instructions for
x86 and for other architectures makes use of memcpy() family of
functions as fallback.

Another major difference is unlike i915_memcpy_from_wc(),
drm_memcpy_from_wc() will not fail if the passed address argument is not
alignment to be used with non-temporal load instructions or if the
platform lacks support for those instructions (non-temporal load
instructions are provided through SSE4.1 instruction set extension).
Instead drm_memcpy_from_wc() continues with fallback functions to
complete the copy.
This relieves the caller from checking the return value of
i915_memcpy_from_wc() and explicitly using a fallback.

Follow up series will be created to remove the memcpy_from_wc functions
from i915 once the dependency is completely removed.

v2: Fixed missing check to find if the address is from system memory or
    io memory and use the right initialization function to construct the
    iosys_map structure (Review feedback from Lucas)

v3: "drm/i915/guc: use the memcpy_from_wc call from the drm" replaced by
    patch "drm/i915/guc: use iosys_map abstraction to access GuC log".
    New patch does a wider change compared to the old patch. It
    completely changes the access to GuC log using iosys_map
    abstraction, in addition to using drm_memcpy_from_wc.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: David Airlie <airlied@linux.ie> 
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Chris Wilson <chris.p.wilson@intel.com>
Cc: Thomas Hellstr_m <thomas.hellstrom@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>

Balasubramani Vivekanandan (7):
  drm: Relax alignment constraint for destination address
  drm: Add drm_memcpy_from_wc() variant which accepts destination
    address
  drm/i915: use the memcpy_from_wc call from the drm
  drm/i915/guc: use iosys_map abstraction to access GuC log
  drm/i915/selftests: use the memcpy_from_wc call from the drm
  drm/i915/gt: Avoid direct dereferencing of io memory
  drm/i915: Avoid dereferencing io mapped memory

 drivers/gpu/drm/drm_cache.c                   | 99 +++++++++++++++++--
 drivers/gpu/drm/i915/gem/i915_gem_object.c    |  8 +-
 drivers/gpu/drm/i915/gt/selftest_reset.c      | 21 ++--
 drivers/gpu/drm/i915/gt/uc/guc_capture_fwif.h |  2 +-
 .../gpu/drm/i915/gt/uc/intel_guc_capture.c    | 52 +++++++---
 drivers/gpu/drm/i915/gt/uc/intel_guc_log.c    | 77 +++++++++++----
 drivers/gpu/drm/i915/gt/uc/intel_guc_log.h    |  3 +-
 drivers/gpu/drm/i915/i915_gpu_error.c         | 45 +++++----
 .../drm/i915/selftests/intel_memory_region.c  | 41 +++++---
 include/drm/drm_cache.h                       |  3 +
 10 files changed, 261 insertions(+), 90 deletions(-)