drm/i915: Emphasize that ctx->id is merely a user handle
This is an Execlists preparatory patch, since they make context ID become an
overloaded term:
- In the software, it was used to distinguish which context userspace was
trying to use.
- In the BSpec, the term is used to describe the 20-bits long field the
hardware uses to it to discriminate the contexts that are submitted to
the ELSP and inform the driver about their current status (via Context
Switch Interrupts and Context Status Buffers).
Initially, I tried to make the different meanings converge, but it proved
impossible:
- The software ctx->id is per-filp, while the hardware one needs to be
globally unique.
- Also, we multiplex several backing states objects per intel_context,
and all of them need unique HW IDs.
- I tried adding a per-filp ID and then composing the HW context ID as:
ctx->id + file_priv->id + ring->id, but the fact that the hardware only
uses 20-bits means we have to artificially limit the number of filps or
contexts the userspace can create.
The ctx->user_handle renaming bits are done with this Cocci patch (plus
manual frobbing of the struct declaration):
@@
struct intel_context c;
@@
- (c).id
+ c.user_handle
@@
struct intel_context *c;
@@
- (c)->id
+ c->user_handle
Also, while we are at it, s/DEFAULT_CONTEXT_ID/DEFAULT_CONTEXT_HANDLE and
change the type to unsigned 32 bits.
v2: s/handle/user_handle and change the type to uint32_t as suggested by
Chris Wilson.
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org> (v1)
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index eeb3e4c..dcef38b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -585,10 +585,10 @@
};
/* This must match up with the value previously used for execbuf2.rsvd1. */
-#define DEFAULT_CONTEXT_ID 0
+#define DEFAULT_CONTEXT_HANDLE 0
struct intel_context {
struct kref ref;
- int id;
+ int user_handle;
uint8_t remap_slice;
struct drm_i915_file_private *file_priv;
struct i915_ctx_hang_stats hang_stats;
@@ -2469,7 +2469,7 @@
static inline bool i915_gem_context_is_default(const struct intel_context *c)
{
- return c->id == DEFAULT_CONTEXT_ID;
+ return c->user_handle == DEFAULT_CONTEXT_HANDLE;
}
int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,