[igt-dev] [i-g-t] i915_drm.h sync

Petri Latvala petri.latvala at intel.com
Thu Sep 2 08:51:31 UTC 2021


On Thu, Sep 02, 2021 at 11:10:57AM +0530, Tejas Upadhyay wrote:
> Sync to get I915_MMAP_OFFSET_FIXED define value.
> 
> Taken from kernel commit:
>     commit 7961c5b60f23 ("drm/i915: Add TTM offset argument to mmap.")
> 
> Signed-off-by: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay at intel.com>

Acked-by: Petri Latvala <petri.latvala at intel.com>

> ---
>  include/drm-uapi/i915_drm.h | 450 +++++++++++++++++++++++++++++-------
>  lib/i915/i915_drm_local.h   |   2 -
>  2 files changed, 369 insertions(+), 83 deletions(-)
> 
> diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h
> index a1c0030c..b9632bb2 100644
> --- a/include/drm-uapi/i915_drm.h
> +++ b/include/drm-uapi/i915_drm.h
> @@ -849,45 +849,94 @@ struct drm_i915_gem_mmap_gtt {
>  	__u64 offset;
>  };
>  
> +/**
> + * struct drm_i915_gem_mmap_offset - Retrieve an offset so we can mmap this buffer object.
> + *
> + * This struct is passed as argument to the `DRM_IOCTL_I915_GEM_MMAP_OFFSET` ioctl,
> + * and is used to retrieve the fake offset to mmap an object specified by &handle.
> + *
> + * The legacy way of using `DRM_IOCTL_I915_GEM_MMAP` is removed on gen12+.
> + * `DRM_IOCTL_I915_GEM_MMAP_GTT` is an older supported alias to this struct, but will behave
> + * as setting the &extensions to 0, and &flags to `I915_MMAP_OFFSET_GTT`.
> + */
>  struct drm_i915_gem_mmap_offset {
> -	/** Handle for the object being mapped. */
> +	/** @handle: Handle for the object being mapped. */
>  	__u32 handle;
> +	/** @pad: Must be zero */
>  	__u32 pad;
>  	/**
> -	 * Fake offset to use for subsequent mmap call
> +	 * @offset: The fake offset to use for subsequent mmap call
>  	 *
>  	 * This is a fixed-size type for 32/64 compatibility.
>  	 */
>  	__u64 offset;
>  
>  	/**
> -	 * Flags for extended behaviour.
> +	 * @flags: Flags for extended behaviour.
>  	 *
> -	 * It is mandatory that one of the MMAP_OFFSET types
> -	 * (GTT, WC, WB, UC, etc) should be included.
> +	 * It is mandatory that one of the `MMAP_OFFSET` types
> +	 * should be included:
> +	 *
> +	 * - `I915_MMAP_OFFSET_GTT`: Use mmap with the object bound to GTT. (Write-Combined)
> +	 * - `I915_MMAP_OFFSET_WC`: Use Write-Combined caching.
> +	 * - `I915_MMAP_OFFSET_WB`: Use Write-Back caching.
> +	 * - `I915_MMAP_OFFSET_FIXED`: Use object placement to determine caching.
> +	 *
> +	 * On devices with local memory `I915_MMAP_OFFSET_FIXED` is the only valid
> +	 * type. On devices without local memory, this caching mode is invalid.
> +	 *
> +	 * As caching mode when specifying `I915_MMAP_OFFSET_FIXED`, WC or WB will
> +	 * be used, depending on the object placement on creation. WB will be used
> +	 * when the object can only exist in system memory, WC otherwise.
>  	 */
>  	__u64 flags;
> -#define I915_MMAP_OFFSET_GTT 0
> -#define I915_MMAP_OFFSET_WC  1
> -#define I915_MMAP_OFFSET_WB  2
> -#define I915_MMAP_OFFSET_UC  3
>  
> -	/*
> -	 * Zero-terminated chain of extensions.
> +#define I915_MMAP_OFFSET_GTT	0
> +#define I915_MMAP_OFFSET_WC	1
> +#define I915_MMAP_OFFSET_WB	2
> +#define I915_MMAP_OFFSET_UC	3
> +#define I915_MMAP_OFFSET_FIXED	4
> +
> +	/**
> +	 * @extensions: Zero-terminated chain of extensions.
>  	 *
>  	 * No current extensions defined; mbz.
>  	 */
>  	__u64 extensions;
>  };
>  
> +/**
> + * struct drm_i915_gem_set_domain - Adjust the objects write or read domain, in
> + * preparation for accessing the pages via some CPU domain.
> + *
> + * Specifying a new write or read domain will flush the object out of the
> + * previous domain(if required), before then updating the objects domain
> + * tracking with the new domain.
> + *
> + * Note this might involve waiting for the object first if it is still active on
> + * the GPU.
> + *
> + * Supported values for @read_domains and @write_domain:
> + *
> + *	- I915_GEM_DOMAIN_WC: Uncached write-combined domain
> + *	- I915_GEM_DOMAIN_CPU: CPU cache domain
> + *	- I915_GEM_DOMAIN_GTT: Mappable aperture domain
> + *
> + * All other domains are rejected.
> + */
>  struct drm_i915_gem_set_domain {
> -	/** Handle for the object */
> +	/** @handle: Handle for the object. */
>  	__u32 handle;
>  
> -	/** New read domains */
> +	/** @read_domains: New read domains. */
>  	__u32 read_domains;
>  
> -	/** New write domain */
> +	/**
> +	 * @write_domain: New write domain.
> +	 *
> +	 * Note that having something in the write domain implies it's in the
> +	 * read domain, and only that read domain.
> +	 */
>  	__u32 write_domain;
>  };
>  
> @@ -1348,12 +1397,11 @@ struct drm_i915_gem_busy {
>  	 * reading from the object simultaneously.
>  	 *
>  	 * The value of each engine class is the same as specified in the
> -	 * I915_CONTEXT_SET_ENGINES parameter and via perf, i.e.
> +	 * I915_CONTEXT_PARAM_ENGINES context parameter and via perf, i.e.
>  	 * I915_ENGINE_CLASS_RENDER, I915_ENGINE_CLASS_COPY, etc.
> -	 * reported as active itself. Some hardware may have parallel
> -	 * execution engines, e.g. multiple media engines, which are
> -	 * mapped to the same class identifier and so are not separately
> -	 * reported for busyness.
> +	 * Some hardware may have parallel execution engines, e.g. multiple
> +	 * media engines, which are mapped to the same class identifier and so
> +	 * are not separately reported for busyness.
>  	 *
>  	 * Caveat emptor:
>  	 * Only the boolean result of this query is reliable; that is whether
> @@ -1364,43 +1412,79 @@ struct drm_i915_gem_busy {
>  };
>  
>  /**
> - * I915_CACHING_NONE
> - *
> - * GPU access is not coherent with cpu caches. Default for machines without an
> - * LLC.
> - */
> -#define I915_CACHING_NONE		0
> -/**
> - * I915_CACHING_CACHED
> - *
> - * GPU access is coherent with cpu caches and furthermore the data is cached in
> - * last-level caches shared between cpu cores and the gpu GT. Default on
> - * machines with HAS_LLC.
> + * struct drm_i915_gem_caching - Set or get the caching for given object
> + * handle.
> + *
> + * Allow userspace to control the GTT caching bits for a given object when the
> + * object is later mapped through the ppGTT(or GGTT on older platforms lacking
> + * ppGTT support, or if the object is used for scanout). Note that this might
> + * require unbinding the object from the GTT first, if its current caching value
> + * doesn't match.
> + *
> + * Note that this all changes on discrete platforms, starting from DG1, the
> + * set/get caching is no longer supported, and is now rejected.  Instead the CPU
> + * caching attributes(WB vs WC) will become an immutable creation time property
> + * for the object, along with the GTT caching level. For now we don't expose any
> + * new uAPI for this, instead on DG1 this is all implicit, although this largely
> + * shouldn't matter since DG1 is coherent by default(without any way of
> + * controlling it).
> + *
> + * Implicit caching rules, starting from DG1:
> + *
> + *     - If any of the object placements (see &drm_i915_gem_create_ext_memory_regions)
> + *       contain I915_MEMORY_CLASS_DEVICE then the object will be allocated and
> + *       mapped as write-combined only.
> + *
> + *     - Everything else is always allocated and mapped as write-back, with the
> + *       guarantee that everything is also coherent with the GPU.
> + *
> + * Note that this is likely to change in the future again, where we might need
> + * more flexibility on future devices, so making this all explicit as part of a
> + * new &drm_i915_gem_create_ext extension is probable.
> + *
> + * Side note: Part of the reason for this is that changing the at-allocation-time CPU
> + * caching attributes for the pages might be required(and is expensive) if we
> + * need to then CPU map the pages later with different caching attributes. This
> + * inconsistent caching behaviour, while supported on x86, is not universally
> + * supported on other architectures. So for simplicity we opt for setting
> + * everything at creation time, whilst also making it immutable, on discrete
> + * platforms.
>   */
> -#define I915_CACHING_CACHED		1
> -/**
> - * I915_CACHING_DISPLAY
> - *
> - * Special GPU caching mode which is coherent with the scanout engines.
> - * Transparently falls back to I915_CACHING_NONE on platforms where no special
> - * cache mode (like write-through or gfdt flushing) is available. The kernel
> - * automatically sets this mode when using a buffer as a scanout target.
> - * Userspace can manually set this mode to avoid a costly stall and clflush in
> - * the hotpath of drawing the first frame.
> - */
> -#define I915_CACHING_DISPLAY		2
> -
>  struct drm_i915_gem_caching {
>  	/**
> -	 * Handle of the buffer to set/get the caching level of. */
> +	 * @handle: Handle of the buffer to set/get the caching level.
> +	 */
>  	__u32 handle;
>  
>  	/**
> -	 * Cacheing level to apply or return value
> +	 * @caching: The GTT caching level to apply or possible return value.
> +	 *
> +	 * The supported @caching values:
> +	 *
> +	 * I915_CACHING_NONE:
> +	 *
> +	 * GPU access is not coherent with CPU caches.  Default for machines
> +	 * without an LLC. This means manual flushing might be needed, if we
> +	 * want GPU access to be coherent.
> +	 *
> +	 * I915_CACHING_CACHED:
> +	 *
> +	 * GPU access is coherent with CPU caches and furthermore the data is
> +	 * cached in last-level caches shared between CPU cores and the GPU GT.
>  	 *
> -	 * bits0-15 are for generic caching control (i.e. the above defined
> -	 * values). bits16-31 are reserved for platform-specific variations
> -	 * (e.g. l3$ caching on gen7). */
> +	 * I915_CACHING_DISPLAY:
> +	 *
> +	 * Special GPU caching mode which is coherent with the scanout engines.
> +	 * Transparently falls back to I915_CACHING_NONE on platforms where no
> +	 * special cache mode (like write-through or gfdt flushing) is
> +	 * available. The kernel automatically sets this mode when using a
> +	 * buffer as a scanout target.  Userspace can manually set this mode to
> +	 * avoid a costly stall and clflush in the hotpath of drawing the first
> +	 * frame.
> +	 */
> +#define I915_CACHING_NONE		0
> +#define I915_CACHING_CACHED		1
> +#define I915_CACHING_DISPLAY		2
>  	__u32 caching;
>  };
>  
> @@ -1639,6 +1723,10 @@ struct drm_i915_gem_context_param {
>  	__u32 size;
>  	__u64 param;
>  #define I915_CONTEXT_PARAM_BAN_PERIOD	0x1
> +/* I915_CONTEXT_PARAM_NO_ZEROMAP has been removed.  On the off chance
> + * someone somewhere has attempted to use it, never re-use this context
> + * param number.
> + */
>  #define I915_CONTEXT_PARAM_NO_ZEROMAP	0x2
>  #define I915_CONTEXT_PARAM_GTT_SIZE	0x3
>  #define I915_CONTEXT_PARAM_NO_ERROR_CAPTURE	0x4
> @@ -1723,24 +1811,8 @@ struct drm_i915_gem_context_param {
>   */
>  #define I915_CONTEXT_PARAM_PERSISTENCE	0xb
>  
> -/*
> - * I915_CONTEXT_PARAM_RINGSIZE:
> - *
> - * Sets the size of the CS ringbuffer to use for logical ring contexts. This
> - * applies a limit of how many batches can be queued to HW before the caller
> - * is blocked due to lack of space for more commands.
> - *
> - * Only reliably possible to be set prior to first use, i.e. during
> - * construction. At any later point, the current execution must be flushed as
> - * the ring can only be changed while the context is idle. Note, the ringsize
> - * can be specified as a constructor property, see
> - * I915_CONTEXT_CREATE_EXT_SETPARAM, but can also be set later if required.
> - *
> - * Only applies to the current set of engine and lost when those engines
> - * are replaced by a new mapping (see I915_CONTEXT_PARAM_ENGINES).
> - *
> - * Must be between 4 - 512 KiB, in intervals of page size [4 KiB].
> - * Default is 16 KiB.
> +/* This API has been removed.  On the off chance someone somewhere has
> + * attempted to use it, never re-use this context param number.
>   */
>  #define I915_CONTEXT_PARAM_RINGSIZE	0xc
>  /* Must be kept compact -- no holes and well documented */
> @@ -1807,6 +1879,69 @@ struct drm_i915_gem_context_param_sseu {
>  	__u32 rsvd;
>  };
>  
> +/**
> + * DOC: Virtual Engine uAPI
> + *
> + * Virtual engine is a concept where userspace is able to configure a set of
> + * physical engines, submit a batch buffer, and let the driver execute it on any
> + * engine from the set as it sees fit.
> + *
> + * This is primarily useful on parts which have multiple instances of a same
> + * class engine, like for example GT3+ Skylake parts with their two VCS engines.
> + *
> + * For instance userspace can enumerate all engines of a certain class using the
> + * previously described `Engine Discovery uAPI`_. After that userspace can
> + * create a GEM context with a placeholder slot for the virtual engine (using
> + * `I915_ENGINE_CLASS_INVALID` and `I915_ENGINE_CLASS_INVALID_NONE` for class
> + * and instance respectively) and finally using the
> + * `I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE` extension place a virtual engine in
> + * the same reserved slot.
> + *
> + * Example of creating a virtual engine and submitting a batch buffer to it:
> + *
> + * .. code-block:: C
> + *
> + * 	I915_DEFINE_CONTEXT_ENGINES_LOAD_BALANCE(virtual, 2) = {
> + * 		.base.name = I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE,
> + * 		.engine_index = 0, // Place this virtual engine into engine map slot 0
> + * 		.num_siblings = 2,
> + * 		.engines = { { I915_ENGINE_CLASS_VIDEO, 0 },
> + * 			     { I915_ENGINE_CLASS_VIDEO, 1 }, },
> + * 	};
> + * 	I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 1) = {
> + * 		.engines = { { I915_ENGINE_CLASS_INVALID,
> + * 			       I915_ENGINE_CLASS_INVALID_NONE } },
> + * 		.extensions = to_user_pointer(&virtual), // Chains after load_balance extension
> + * 	};
> + * 	struct drm_i915_gem_context_create_ext_setparam p_engines = {
> + * 		.base = {
> + * 			.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
> + * 		},
> + * 		.param = {
> + * 			.param = I915_CONTEXT_PARAM_ENGINES,
> + * 			.value = to_user_pointer(&engines),
> + * 			.size = sizeof(engines),
> + * 		},
> + * 	};
> + * 	struct drm_i915_gem_context_create_ext create = {
> + * 		.flags = I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS,
> + * 		.extensions = to_user_pointer(&p_engines);
> + * 	};
> + *
> + * 	ctx_id = gem_context_create_ext(drm_fd, &create);
> + *
> + * 	// Now we have created a GEM context with its engine map containing a
> + * 	// single virtual engine. Submissions to this slot can go either to
> + * 	// vcs0 or vcs1, depending on the load balancing algorithm used inside
> + * 	// the driver. The load balancing is dynamic from one batch buffer to
> + * 	// another and transparent to userspace.
> + *
> + * 	...
> + * 	execbuf.rsvd1 = ctx_id;
> + * 	execbuf.flags = 0; // Submits to index 0 which is the virtual engine
> + * 	gem_execbuf(drm_fd, &execbuf);
> + */
> +
>  /*
>   * i915_context_engines_load_balance:
>   *
> @@ -1883,6 +2018,61 @@ struct i915_context_engines_bond {
>  	struct i915_engine_class_instance engines[N__]; \
>  } __attribute__((packed)) name__
>  
> +/**
> + * DOC: Context Engine Map uAPI
> + *
> + * Context engine map is a new way of addressing engines when submitting batch-
> + * buffers, replacing the existing way of using identifiers like `I915_EXEC_BLT`
> + * inside the flags field of `struct drm_i915_gem_execbuffer2`.
> + *
> + * To use it created GEM contexts need to be configured with a list of engines
> + * the user is intending to submit to. This is accomplished using the
> + * `I915_CONTEXT_PARAM_ENGINES` parameter and `struct
> + * i915_context_param_engines`.
> + *
> + * For such contexts the `I915_EXEC_RING_MASK` field becomes an index into the
> + * configured map.
> + *
> + * Example of creating such context and submitting against it:
> + *
> + * .. code-block:: C
> + *
> + * 	I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, 2) = {
> + * 		.engines = { { I915_ENGINE_CLASS_RENDER, 0 },
> + * 			     { I915_ENGINE_CLASS_COPY, 0 } }
> + * 	};
> + * 	struct drm_i915_gem_context_create_ext_setparam p_engines = {
> + * 		.base = {
> + * 			.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
> + * 		},
> + * 		.param = {
> + * 			.param = I915_CONTEXT_PARAM_ENGINES,
> + * 			.value = to_user_pointer(&engines),
> + * 			.size = sizeof(engines),
> + * 		},
> + * 	};
> + * 	struct drm_i915_gem_context_create_ext create = {
> + * 		.flags = I915_CONTEXT_CREATE_FLAGS_USE_EXTENSIONS,
> + * 		.extensions = to_user_pointer(&p_engines);
> + * 	};
> + *
> + * 	ctx_id = gem_context_create_ext(drm_fd, &create);
> + *
> + * 	// We have now created a GEM context with two engines in the map:
> + * 	// Index 0 points to rcs0 while index 1 points to bcs0. Other engines
> + * 	// will not be accessible from this context.
> + *
> + * 	...
> + * 	execbuf.rsvd1 = ctx_id;
> + * 	execbuf.flags = 0; // Submits to index 0, which is rcs0 for this context
> + * 	gem_execbuf(drm_fd, &execbuf);
> + *
> + * 	...
> + * 	execbuf.rsvd1 = ctx_id;
> + * 	execbuf.flags = 1; // Submits to index 0, which is bcs0 for this context
> + * 	gem_execbuf(drm_fd, &execbuf);
> + */
> +
>  struct i915_context_param_engines {
>  	__u64 extensions; /* linked chain of extension blocks, 0 terminates */
>  #define I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE 0 /* see i915_context_engines_load_balance */
> @@ -1901,20 +2091,10 @@ struct drm_i915_gem_context_create_ext_setparam {
>  	struct drm_i915_gem_context_param param;
>  };
>  
> -struct drm_i915_gem_context_create_ext_clone {
> +/* This API has been removed.  On the off chance someone somewhere has
> + * attempted to use it, never re-use this extension number.
> + */
>  #define I915_CONTEXT_CREATE_EXT_CLONE 1
> -	struct i915_user_extension base;
> -	__u32 clone_id;
> -	__u32 flags;
> -#define I915_CONTEXT_CLONE_ENGINES	(1u << 0)
> -#define I915_CONTEXT_CLONE_FLAGS	(1u << 1)
> -#define I915_CONTEXT_CLONE_SCHEDATTR	(1u << 2)
> -#define I915_CONTEXT_CLONE_SSEU		(1u << 3)
> -#define I915_CONTEXT_CLONE_TIMELINE	(1u << 4)
> -#define I915_CONTEXT_CLONE_VM		(1u << 5)
> -#define I915_CONTEXT_CLONE_UNKNOWN -(I915_CONTEXT_CLONE_VM << 1)
> -	__u64 rsvd;
> -};
>  
>  struct drm_i915_gem_context_destroy {
>  	__u32 ctx_id;
> @@ -1986,14 +2166,52 @@ struct drm_i915_reset_stats {
>  	__u32 pad;
>  };
>  
> +/**
> + * struct drm_i915_gem_userptr - Create GEM object from user allocated memory.
> + *
> + * Userptr objects have several restrictions on what ioctls can be used with the
> + * object handle.
> + */
>  struct drm_i915_gem_userptr {
> +	/**
> +	 * @user_ptr: The pointer to the allocated memory.
> +	 *
> +	 * Needs to be aligned to PAGE_SIZE.
> +	 */
>  	__u64 user_ptr;
> +
> +	/**
> +	 * @user_size:
> +	 *
> +	 * The size in bytes for the allocated memory. This will also become the
> +	 * object size.
> +	 *
> +	 * Needs to be aligned to PAGE_SIZE, and should be at least PAGE_SIZE,
> +	 * or larger.
> +	 */
>  	__u64 user_size;
> +
> +	/**
> +	 * @flags:
> +	 *
> +	 * Supported flags:
> +	 *
> +	 * I915_USERPTR_READ_ONLY:
> +	 *
> +	 * Mark the object as readonly, this also means GPU access can only be
> +	 * readonly. This is only supported on HW which supports readonly access
> +	 * through the GTT. If the HW can't support readonly access, an error is
> +	 * returned.
> +	 *
> +	 * I915_USERPTR_UNSYNCHRONIZED:
> +	 *
> +	 * NOT USED. Setting this flag will result in an error.
> +	 */
>  	__u32 flags;
>  #define I915_USERPTR_READ_ONLY 0x1
>  #define I915_USERPTR_UNSYNCHRONIZED 0x80000000
>  	/**
> -	 * Returned handle for the object.
> +	 * @handle: Returned handle for the object.
>  	 *
>  	 * Object handles are nonzero.
>  	 */
> @@ -2376,6 +2594,76 @@ struct drm_i915_query_topology_info {
>  	__u8 data[];
>  };
>  
> +/**
> + * DOC: Engine Discovery uAPI
> + *
> + * Engine discovery uAPI is a way of enumerating physical engines present in a
> + * GPU associated with an open i915 DRM file descriptor. This supersedes the old
> + * way of using `DRM_IOCTL_I915_GETPARAM` and engine identifiers like
> + * `I915_PARAM_HAS_BLT`.
> + *
> + * The need for this interface came starting with Icelake and newer GPUs, which
> + * started to establish a pattern of having multiple engines of a same class,
> + * where not all instances were always completely functionally equivalent.
> + *
> + * Entry point for this uapi is `DRM_IOCTL_I915_QUERY` with the
> + * `DRM_I915_QUERY_ENGINE_INFO` as the queried item id.
> + *
> + * Example for getting the list of engines:
> + *
> + * .. code-block:: C
> + *
> + * 	struct drm_i915_query_engine_info *info;
> + * 	struct drm_i915_query_item item = {
> + * 		.query_id = DRM_I915_QUERY_ENGINE_INFO;
> + * 	};
> + * 	struct drm_i915_query query = {
> + * 		.num_items = 1,
> + * 		.items_ptr = (uintptr_t)&item,
> + * 	};
> + * 	int err, i;
> + *
> + * 	// First query the size of the blob we need, this needs to be large
> + * 	// enough to hold our array of engines. The kernel will fill out the
> + * 	// item.length for us, which is the number of bytes we need.
> + * 	//
> + * 	// Alternatively a large buffer can be allocated straight away enabling
> + * 	// querying in one pass, in which case item.length should contain the
> + * 	// length of the provided buffer.
> + * 	err = ioctl(fd, DRM_IOCTL_I915_QUERY, &query);
> + * 	if (err) ...
> + *
> + * 	info = calloc(1, item.length);
> + * 	// Now that we allocated the required number of bytes, we call the ioctl
> + * 	// again, this time with the data_ptr pointing to our newly allocated
> + * 	// blob, which the kernel can then populate with info on all engines.
> + * 	item.data_ptr = (uintptr_t)&info,
> + *
> + * 	err = ioctl(fd, DRM_IOCTL_I915_QUERY, &query);
> + * 	if (err) ...
> + *
> + * 	// We can now access each engine in the array
> + * 	for (i = 0; i < info->num_engines; i++) {
> + * 		struct drm_i915_engine_info einfo = info->engines[i];
> + * 		u16 class = einfo.engine.class;
> + * 		u16 instance = einfo.engine.instance;
> + * 		....
> + * 	}
> + *
> + * 	free(info);
> + *
> + * Each of the enumerated engines, apart from being defined by its class and
> + * instance (see `struct i915_engine_class_instance`), also can have flags and
> + * capabilities defined as documented in i915_drm.h.
> + *
> + * For instance video engines which support HEVC encoding will have the
> + * `I915_VIDEO_CLASS_CAPABILITY_HEVC` capability bit set.
> + *
> + * Engine discovery only fully comes to its own when combined with the new way
> + * of addressing engines when submitting batch buffers using contexts with
> + * engine maps configured.
> + */
> +
>  /**
>   * struct drm_i915_engine_info
>   *
> diff --git a/lib/i915/i915_drm_local.h b/lib/i915/i915_drm_local.h
> index 0e3cef81..dd646aed 100644
> --- a/lib/i915/i915_drm_local.h
> +++ b/lib/i915/i915_drm_local.h
> @@ -20,8 +20,6 @@ extern "C" {
>   * clean these up when kernel uapi headers are sync'd.
>   */
>  
> -#define I915_MMAP_OFFSET_FIXED 4
> -
>  #if defined(__cplusplus)
>  }
>  #endif
> -- 
> 2.31.1
> 


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