drm/i915/gt: Poison residual state [HWSP] across resume.

Since we may lose the content of any buffer when we relinquish control
of the system (e.g. suspend/resume), we have to be careful not to rely
on regaining control. A good method to detect when we might be using
garbage is by always injecting that garbage prior to first use on
load/resume/etc.

v2: Drop sanitize callback on cleanup
v3: Move seqno reset to timeline enter, so we reset all timelines.
However, this is done on every activation during runtime and not reset.
The similar level of paranoia we apply to correcting context state after
a period of inactivity.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Venkata Ramana Nayana <venkata.ramana.nayana@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200421092504.7416-1-chris@chris-wilson.co.uk

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_timeline.h b/drivers/gpu/drm/i915/gt/intel_timeline.h
index f5b7eade3809..c8e59a333182 100644
--- a/drivers/gpu/drm/i915/gt/intel_timeline.h
+++ b/drivers/gpu/drm/i915/gt/intel_timeline.h
@@ -84,6 +84,8 @@ int intel_timeline_get_seqno(struct intel_timeline *tl,
 void intel_timeline_exit(struct intel_timeline *tl);
 void intel_timeline_unpin(struct intel_timeline *tl);
 
+void intel_timeline_reset_seqno(const struct intel_timeline *tl);
+
 int intel_timeline_read_hwsp(struct i915_request *from,
 			     struct i915_request *until,
 			     u32 *hwsp_offset);