drm/i915: Use MI_BATCH_BUFFER_START on 830/845

MI_BATCH_BUFFER is nasty since it requires that userspace pass in the
correct batch length.

Let's switch to using MI_BATCH_BUFFER_START instead (like we do on
other platforms). Then we don't have to specify the batch length
at all, and the CS will instead execute until it sees the
MI_BATCH_BUFFER_END.

We still need the batch length since we do the CS TLB workaround
and copy the batch into the permanently pinned scratch object
and execute it from there. But for this we can simply use the
batch object length when the user hasn't specified the actual
batch length. So specifying the batch length becomes just a
way to optimize the batch copy a little bit.

We lost batch_len from a bunch of igts (including the quiesce batch)
so without this igt is utterly broken on 830/845. Also some igts such
as gem_cpu_reloc never specified the batch_len and so didn't work.
With MI_BATCH_BUFFER_START we don't have to fix up igt every time
someone forgets that 830/845 exist.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450110229-30450-11-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index dccb517361b3f1763e3241f9c87f04c58ec4d7fc..d469c4779ff5f67f36c0c1fcf9aee4d229c43131 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1309,6 +1309,9 @@ i915_gem_ringbuffer_submission(struct i915_execbuffer_params *params,
        exec_start = params->batch_obj_vm_offset +
                     params->args_batch_start_offset;
 
+       if (exec_len == 0)
+               exec_len = params->batch_obj->base.size;
+
        ret = ring->dispatch_execbuffer(params->request,
                                        exec_start, exec_len,
                                        params->dispatch_flags);

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index d9e0b400294d371bb05fd591b242707f9c91c9e7..4060acf0601a6fdac57486fde04420a1b99e672e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1865,15 +1865,13 @@ i830_dispatch_execbuffer(struct drm_i915_gem_request *req,
                offset = cs_offset;
        }
 
-       ret = intel_ring_begin(req, 4);
+       ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;
 
-       intel_ring_emit(ring, MI_BATCH_BUFFER);
+       intel_ring_emit(ring, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
        intel_ring_emit(ring, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
                                        0 : MI_BATCH_NON_SECURE));
-       intel_ring_emit(ring, offset + len - 8);
-       intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);
 
        return 0;