drm/i915: Restore context and pd for ringbuffer submission after reset
Following a reset, the context and page directory registers are lost.
However, the queue of requests that we resubmit after the reset may
depend upon them - the registers are restored from a context image, but
that restore may be inhibited and may simply be absent from the request
if it was in the middle of a sequence using the same context. If we
prime the CCID/PD registers with the first request in the queue (even
for the hung request), we prevent invalid memory access for the
following requests (and continually hung engines).
v2: Magic BIT(8), reserved for future use but still appears unused.
v3: Some commentary on handling innocent vs guilty requests
v4: Add a wait for PD_BASE fetch. The reload appears to be instant on my
Ivybridge, but this bit probably exists for a reason.
Fixes: 821ed7df6e2a ("drm/i915: Update reset path to fix incomplete requests")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170207152437.4252-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 4b5761d..bd2ff1f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3307,8 +3307,10 @@ enum skl_disp_power_wells {
/*
* Logical Context regs
*/
-#define CCID _MMIO(0x2180)
-#define CCID_EN (1<<0)
+#define CCID _MMIO(0x2180)
+#define CCID_EN BIT(0)
+#define CCID_EXTENDED_STATE_RESTORE BIT(2)
+#define CCID_EXTENDED_STATE_SAVE BIT(3)
/*
* Notes on SNB/IVB/VLV context size:
* - Power context is saved elsewhere (LLC or stolen)