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)
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 the memcpy_from_wc call from the drm 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 | 98 +++++++++++++++++-- drivers/gpu/drm/i915/gem/i915_gem_object.c | 6 +- drivers/gpu/drm/i915/gt/selftest_reset.c | 21 ++-- drivers/gpu/drm/i915/gt/uc/intel_guc_log.c | 15 ++- drivers/gpu/drm/i915/i915_gpu_error.c | 45 +++++---- .../drm/i915/selftests/intel_memory_region.c | 41 +++++--- include/drm/drm_cache.h | 3 + 7 files changed, 174 insertions(+), 55 deletions(-)