[Intel-gfx] [RFC v3] drm/i915: Select engines via class and instance in execbuffer2
Chris Wilson
chris at chris-wilson.co.uk
Wed May 17 16:44:08 UTC 2017
On Wed, May 17, 2017 at 04:40:57PM +0100, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>
> Building on top of the previous patch which exported the concept
> of engine classes and instances, we can also use this instead of
> the current awkward engine selection uAPI.
>
> This is primarily interesting for the VCS engine selection which
> is a) currently done via disjoint set of flags, and b) the
> current I915_EXEC_BSD flags has different semantics depending on
> the underlying hardware which is bad.
>
> Proposed idea here is to reserve 16-bits of flags, to pass in
> the engine class and instance (8 bits each), and a new flag
> named I915_EXEC_CLASS_INSTACE to tell the kernel this new engine
> selection API is in use.
>
> The new uAPI also removes access to the weak VCS engine
> balancing as currently existing in the driver.
>
> Example usage to send a command to VCS0:
>
> eb.flags = i915_execbuffer2_engine(DRM_I915_ENGINE_CLASS_VIDEO_DECODE, 0);
>
> Or to send a command to VCS1:
>
> eb.flags = i915_execbuffer2_engine(DRM_I915_ENGINE_CLASS_VIDEO_DECODE, 1);
>
> v2:
> * Fix unknown flags mask.
> * Use I915_EXEC_RING_MASK for class. (Chris Wilson)
>
> v3:
> * Add a map for fast class-instance engine lookup. (Chris Wilson)
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Ben Widawsky <ben at bwidawsk.net>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Jon Bloomfield <jon.bloomfield at intel.com>
> Cc: Daniel Charles <daniel.charles at intel.com>
> Cc: "Rogozhkin, Dmitry V" <dmitry.v.rogozhkin at intel.com>
> Cc: Oscar Mateo <oscar.mateo at intel.com>
> Cc: "Gong, Zhipeng" <zhipeng.gong at intel.com>
> Cc: intel-vaapi-media at lists.01.org
> Cc: mesa-dev at lists.freedesktop.org
> ---
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 30 ++++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/i915_reg.h | 3 +++
> drivers/gpu/drm/i915/intel_engine_cs.c | 7 +++++++
> include/uapi/drm/i915_drm.h | 11 ++++++++++-
> 5 files changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 5dfa4a12e647..7bf4fd42480c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2066,6 +2066,7 @@ struct drm_i915_private {
> struct pci_dev *bridge_dev;
> struct i915_gem_context *kernel_context;
> struct intel_engine_cs *engine[I915_NUM_ENGINES];
> + struct intel_engine_cs *engine_class[MAX_ENGINE_CLASS + 1][MAX_ENGINE_INSTANCE + 1];
> struct i915_vma *semaphore;
>
> struct drm_dma_handle *status_page_dmah;
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index af1965774e7b..c1ad49ab64cd 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1492,6 +1492,33 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
> return file_priv->bsd_engine;
> }
>
> +extern u8 user_class_map[DRM_I915_ENGINE_CLASS_MAX];
> +
> +static struct intel_engine_cs *get_engine_class(struct drm_i915_private *i915,
> + u8 class, u8 instance)
> +{
> + if (class > MAX_ENGINE_CLASS || instance > MAX_ENGINE_INSTANCE)
> + return NULL;
> +
> + return i915->engine_class[class][instance];
> +}
Be bold make this this an intel_engine_lookup(), I forsee some other
users appearing very shortly.
> +static struct intel_engine_cs *
> +eb_select_engine_class_instance(struct drm_i915_private *i915,
> + struct drm_i915_gem_execbuffer2 *args)
> +{
> + u8 class, instance;
> +
> + class = args->flags & I915_EXEC_RING_MASK;
> + if (class >= DRM_I915_ENGINE_CLASS_MAX)
> + return NULL;
> +
> + instance = (args->flags >> I915_EXEC_INSTANCE_SHIFT) &&
> + I915_EXEC_INSTANCE_MASK;
> +
> + return get_engine_class(i915, user_class_map[class], instance);
> +}
> +
> #define I915_USER_RINGS (4)
>
> static const enum intel_engine_id user_ring_map[I915_USER_RINGS + 1] = {
> @@ -1510,6 +1537,9 @@ eb_select_engine(struct drm_i915_private *dev_priv,
> unsigned int user_ring_id = args->flags & I915_EXEC_RING_MASK;
> struct intel_engine_cs *engine;
>
> + if (args->flags & I915_EXEC_CLASS_INSTANCE)
> + return eb_select_engine_class_instance(dev_priv, args);
> +
> if (user_ring_id > I915_USER_RINGS) {
> DRM_DEBUG("execbuf with unknown ring: %u\n", user_ring_id);
> return NULL;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index ee144ec57935..a3b59043b991 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -92,6 +92,9 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
> #define VIDEO_ENHANCEMENT_CLASS 2
> #define COPY_ENGINE_CLASS 3
> #define OTHER_CLASS 4
> +#define MAX_ENGINE_CLASS 4
> +
> +#define MAX_ENGINE_INSTANCE 1
We also need the names in the uapi.h as well. Do we want to mention
OTHER_CLASS before it is defined? I trust your crystal ball.
Amusingly I notice that you do claim that you have these names in the
changelog. :) We don't need DRM_I915 all the time. I915_ENGINE_CLASS is
going to be unique, at least for those users of i915_drm.h
> /* PCI config space */
>
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index 7566cf48012f..c5ad51c43d23 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -225,7 +225,14 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
>
> ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);
>
> + if (WARN_ON(info->class > MAX_ENGINE_CLASS ||
> + info->instance > MAX_ENGINE_INSTANCE ||
> + dev_priv->engine_class[info->class][info->instance]))
Spread these out or add a message telling what was wrong.
> + return -EINVAL;
> +
> + dev_priv->engine_class[info->class][info->instance] = engine;
> dev_priv->engine[id] = engine;
> +
> return 0;
> }
>
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 2ac6667e57ea..6a26bdf5e684 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -906,7 +906,12 @@ struct drm_i915_gem_execbuffer2 {
> */
> #define I915_EXEC_FENCE_OUT (1<<17)
>
> -#define __I915_EXEC_UNKNOWN_FLAGS (-(I915_EXEC_FENCE_OUT<<1))
> +#define I915_EXEC_CLASS_INSTANCE (1<<18)
> +
> +#define I915_EXEC_INSTANCE_SHIFT (19)
> +#define I915_EXEC_INSTANCE_MASK (0xff << I915_EXEC_INSTANCE_SHIFT)
> +
> +#define __I915_EXEC_UNKNOWN_FLAGS (-((1 << 27) << 1))
>
> #define I915_EXEC_CONTEXT_ID_MASK (0xffffffff)
> #define i915_execbuffer2_set_context_id(eb2, context) \
> @@ -914,6 +919,10 @@ struct drm_i915_gem_execbuffer2 {
> #define i915_execbuffer2_get_context_id(eb2) \
> ((eb2).rsvd1 & I915_EXEC_CONTEXT_ID_MASK)
>
> +#define i915_execbuffer2_engine(class, instance) \
> + (I915_EXEC_CLASS_INSTANCE | (class) | \
> + ((instance) << I915_EXEC_INSTANCE_SHIFT))
(class |
(instance) << I915_EXEC_INSTANCE_SHIFT |
I915_EXEC_CLASS_INSTANCE)
Just suggesting to spread it out over another line for better
readability.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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