Add a simple helper to read data with the CPU from the page of a GEM object. Do the read either via a kmap if the object has struct pages or an iomap otherwise. This is needed by the next patch, reading a u64 value from the object (w/o requiring the obj to be mapped to the GPU).
Suggested by Chris. Cc: Chris Wilson <[email protected]> Signed-off-by: Imre Deak <[email protected]> --- drivers/gpu/drm/i915/gem/i915_gem_object.c | 75 ++++++++++++++++++++++ drivers/gpu/drm/i915/gem/i915_gem_object.h | 2 + 2 files changed, 77 insertions(+) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c index 00d24000b5e8..010f8d735e40 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c @@ -32,6 +32,7 @@ #include "i915_gem_mman.h" #include "i915_gem_object.h" #include "i915_globals.h" +#include "i915_memcpy.h" #include "i915_trace.h" static struct i915_global_object { @@ -383,6 +384,80 @@ void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj, } } +static void +i915_gem_object_read_from_page_kmap(struct drm_i915_gem_object *obj, unsigned long offset, int size, void *dst) +{ + const void *src_map; + const void *src_ptr; + + src_map = kmap_atomic(i915_gem_object_get_page(obj, offset >> PAGE_SHIFT)); + + src_ptr = src_map + offset_in_page(offset); + if (!(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)) + drm_clflush_virt_range((void *)src_ptr, size); + memcpy(dst, src_ptr, size); + + kunmap_atomic((void *)src_map); +} + +static void +i915_gem_object_read_from_page_iomap(struct drm_i915_gem_object *obj, unsigned long offset, int size, void *dst) +{ + const void __iomem *src_map; + const void __iomem *src_ptr; + + src_map = io_mapping_map_wc(&obj->mm.region->iomap, + i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT), + PAGE_SIZE); + + src_ptr = src_map + offset_in_page(offset); + if (!i915_memcpy_from_wc(dst, src_ptr, size)) + memcpy(dst, src_ptr, size); + + io_mapping_unmap((void __iomem *)src_map); +} + +/** + * i915_gem_object_read_from_page - read data from the page of a GEM object + * @obj: GEM object to read from + * @offset: offset within the object + * @size: size to read + * @dst: buffer to store the read data + * + * Reads data from @obj after syncing against any pending GPU writes on it. + * The requested region to read from can't cross a page boundary. + * + * Returns 0 on sucess, negative error code on failre. + */ +int i915_gem_object_read_from_page(struct drm_i915_gem_object *obj, unsigned long offset, size_t size, void *dst) +{ + int ret; + + WARN_ON(offset + size > obj->base.size || + offset_in_page(offset) + size > PAGE_SIZE); + + i915_gem_object_lock(obj, NULL); + + ret = i915_gem_object_wait(obj, 0, MAX_SCHEDULE_TIMEOUT); + if (ret) + goto unlock; + + ret = i915_gem_object_pin_pages(obj); + if (ret) + goto unlock; + + if (i915_gem_object_has_struct_page(obj)) + i915_gem_object_read_from_page_kmap(obj, offset, size, dst); + else + i915_gem_object_read_from_page_iomap(obj, offset, size, dst); + + i915_gem_object_unpin_pages(obj); +unlock: + i915_gem_object_unlock(obj); + + return ret; +} + void i915_gem_init__objects(struct drm_i915_private *i915) { INIT_WORK(&i915->mm.free_work, __i915_gem_free_work); diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h index be14486f63a7..75223f472a2b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h @@ -540,4 +540,6 @@ i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj, __i915_gem_object_invalidate_frontbuffer(obj, origin); } +int i915_gem_object_read_from_page(struct drm_i915_gem_object *obj, unsigned long offset, size_t size, void *dst); + #endif -- 2.25.1 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
