drm/i915: Cleanup some of the CSB handling
I think this patch is a worthwhile cleanup even if it might look only marginally
useful. It gets more useful in upcoming patches and for handling of future GEN
platforms.
The only non-mechanical part of this is the removal of the extra & operation on
the ring->next_context_status_buffer. This is safe because right above this, we
already did a modulus operation.
Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452018609-10142-2-git-send-email-benjamin.widawsky@intel.com
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 8096c6a..7fb2035 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -516,7 +516,7 @@
status_pointer = I915_READ(RING_CONTEXT_STATUS_PTR(ring));
read_pointer = ring->next_context_status_buffer;
- write_pointer = status_pointer & GEN8_CSB_PTR_MASK;
+ write_pointer = GEN8_CSB_WRITE_PTR(status_pointer);
if (read_pointer > write_pointer)
write_pointer += GEN8_CSB_ENTRIES;
@@ -559,10 +559,11 @@
WARN(submit_contexts > 2, "More than two context complete events?\n");
ring->next_context_status_buffer = write_pointer % GEN8_CSB_ENTRIES;
+ /* Update the read pointer to the old write pointer. Manual ringbuffer
+ * management ftw </sarcasm> */
I915_WRITE(RING_CONTEXT_STATUS_PTR(ring),
- _MASKED_FIELD(GEN8_CSB_PTR_MASK << 8,
- ((u32)ring->next_context_status_buffer &
- GEN8_CSB_PTR_MASK) << 8));
+ _MASKED_FIELD(GEN8_CSB_READ_PTR_MASK,
+ ring->next_context_status_buffer << 8));
}
static int execlists_context_queue(struct drm_i915_gem_request *request)
@@ -1506,9 +1507,11 @@
* | Suspend-to-idle (freeze) | Suspend-to-RAM (mem) |
* BDW | CSB regs not reset | CSB regs reset |
* CHT | CSB regs not reset | CSB regs not reset |
+ * SKL | ? | ? |
+ * BXT | ? | ? |
*/
- next_context_status_buffer_hw = (I915_READ(RING_CONTEXT_STATUS_PTR(ring))
- & GEN8_CSB_PTR_MASK);
+ next_context_status_buffer_hw =
+ GEN8_CSB_WRITE_PTR(I915_READ(RING_CONTEXT_STATUS_PTR(ring)));
/*
* When the CSB registers are reset (also after power-up / gpu reset),