Re: [PATCH 01/13] drm/i915: Refactor shmem pread setup

Jani Nikula
2014-03-06T12:14:04Z

On Tue, 18 Feb 2014, bradley.d.volkin@intel.com wrote:
> From: Brad Volkin <bradley.d.volkin@intel.com>
>
> The command parser is going to need the same synchronization and
> setup logic, so factor it out for reuse.
>
> v2: Add a check that the object is backed by shmem
>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 3 +++
> drivers/gpu/drm/i915/i915_gem.c | 51 ++++++++++++++++++++++++++++++-----------
> 2 files changed, 40 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 8c64831..582035b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2097,6 +2097,9 @@ void i915_gem_release_all_mmaps(struct drm_i915_private *dev_priv);
> void i915_gem_release_mmap(struct drm_i915_gem_object *obj);
> void i915_gem_lastclose(struct drm_device *dev);
>
> +int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
> + int *needs_clflush);
> +
> int __must_check i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
> static inline struct page *i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n)
> {
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 3618bb0..83990cb 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -326,6 +326,42 @@ __copy_from_user_swizzled(char *gpu_vaddr, int gpu_offset,
> return 0;
> }
>
> +/*
> + * Pins the specified object's pages and synchronizes the object with
> + * GPU accesses. Sets needs_clflush to non-zero if the caller should
> + * flush the object from the CPU cache.
> + */
> +int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
> + int *needs_clflush)
> +{
> + int ret;
> +
> + *needs_clflush = 0;
> +
> + if (!obj->base.filp)
> + return -EINVAL;
> +
> + if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU)) {
> + /* If we're not in the cpu read domain, set ourself into the gtt
> + * read domain and manually flush cachelines (if required). This
> + * optimizes for the case when the gpu will dirty the data
> + * anyway again before the next pread happens. */
> + *needs_clflush = !cpu_cache_is_coherent(obj->base.dev,
> + obj->cache_level);
> + ret = i915_gem_object_wait_rendering(obj, true);
> + if (ret)
> + return ret;
> + }
> +
> + ret = i915_gem_object_get_pages(obj);
> + if (ret)
> + return ret;
> +
> + i915_gem_object_pin_pages(obj);
> +
> + return ret;
> +}
> +
> /* Per-page copy function for the shmem pread fastpath.
> * Flushes invalid cachelines before reading the target if
> * needs_clflush is set. */
> @@ -423,23 +459,10 @@ i915_gem_shmem_pread(struct drm_device *dev,
>
> obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);
>
> - if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU)) {
> - /* If we're not in the cpu read domain, set ourself into the gtt
> - * read domain and manually flush cachelines (if required). This
> - * optimizes for the case when the gpu will dirty the data
> - * anyway again before the next pread happens. */
> - needs_clflush = !cpu_cache_is_coherent(dev, obj->cache_level);
> - ret = i915_gem_object_wait_rendering(obj, true);
> - if (ret)
> - return ret;
> - }
> -
> - ret = i915_gem_object_get_pages(obj);
> + ret = i915_gem_obj_prepare_shmem_read(obj, &needs_clflush);
> if (ret)
> return ret;
>
> - i915_gem_object_pin_pages(obj);
> -
> offset = args->offset;
>
> for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
> --
> 1.8.3.2
>
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--
Jani Nikula, Intel Open Source Technology Center