[Intel-gfx] [PATCH v2 0/7] drm/i915: Use the memcpy_from_wc function from drm

[Das, Nirmoy]

looks good to me overall but I would get others r-b.

Patches 1-3 Reviewed-by: Nirmoy Das <nirmoy.das at intel.com>

Patches 4-7 Acked-by: Nirmoy Das <nirmoy.das at intel.com>

On 03/03/2022 19:00, Balasubramani Vivekanandan wrote:
> 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 at intel.com>
> Cc: Lucas De Marchi<lucas.demarchi at intel.com>  
> Cc: David Airlie<airlied at linux.ie>
> Cc: Daniel Vetter<daniel at ffwll.ch>
> Cc: Chris Wilson<chris.p.wilson at intel.com>  
> Cc: Thomas Hellstr_m<thomas.hellstrom at linux.intel.com>  
> Cc: Joonas Lahtinen<joonas.lahtinen at linux.intel.com>
> Cc: Rodrigo Vivi<rodrigo.vivi at intel.com>
> Cc: Tvrtko Ursulin<tvrtko.ursulin at linux.intel.com>
> Cc: Nirmoy Das<nirmoy.das at 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(-)
>