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authorChris Wilson2016-08-02 23:50:29 +0200
committerChris Wilson2016-08-02 23:58:24 +0200
commitc5efa1ad09784905ae31cd65b659cc73c09fd290 (patch)
treeb87da28fd7e4da5eada8378eeb20a397510c5a2b /drivers/gpu/drm/i915/intel_ringbuffer.h
parentdrm/i915: Remove intel_ring_get_tail() (diff)
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drm/i915: Convert engine->write_tail to operate on a request
If we rewrite the I915_WRITE_TAIL specialisation for the legacy ringbuffer as submitting the request onto the ringbuffer, we can unify the vfunc with both execlists and GuC in the next patch. v2: Drop the modulus from the I915_WRITE_TAIL as it is currently being applied in intel_ring_advance() after every command packet, and add a comment explaining why we need the modulus at all. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-22-git-send-email-chris@chris-wilson.co.uk Link: http://patchwork.freedesktop.org/patch/msgid/1470174640-18242-12-git-send-email-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/intel_ringbuffer.h')
-rw-r--r--drivers/gpu/drm/i915/intel_ringbuffer.h10
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 0c3c7185d9ad..14d2ea36fb88 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -204,8 +204,6 @@ struct intel_engine_cs {
int (*init_context)(struct drm_i915_gem_request *req);
- void (*write_tail)(struct intel_engine_cs *engine,
- u32 value);
int (*add_request)(struct drm_i915_gem_request *req);
/* Some chipsets are not quite as coherent as advertised and need
* an expensive kick to force a true read of the up-to-date seqno.
@@ -296,6 +294,7 @@ struct intel_engine_cs {
#define I915_DISPATCH_SECURE 0x1
#define I915_DISPATCH_PINNED 0x2
#define I915_DISPATCH_RS 0x4
+ void (*submit_request)(struct drm_i915_gem_request *req);
/**
* List of objects currently involved in rendering from the
@@ -461,6 +460,13 @@ static inline void intel_ring_emit_reg(struct intel_ring *ring, i915_reg_t reg)
static inline void intel_ring_advance(struct intel_ring *ring)
{
+ /* The modulus is required so that we avoid writing
+ * request->tail == ring->size, rather than the expected 0,
+ * into the RING_TAIL register as that can cause a GPU hang.
+ * As this is only strictly required for the request->tail,
+ * and only then as we write the value into hardware, we can
+ * one day remove the modulus after every command packet.
+ */
ring->tail &= ring->size - 1;
}