From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 22 May 2018 11:19:37 +0100
Subject: drm/i915/execlists: Wait for ELSP submission on restart
Git-commit: fe25f3048322f32131a151ebe213f52821322f9c
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
After a reset, we will ensure that there is at least one request
submitted to HW to ensure that a context is loaded for powersaving.
Let's wait for this submission via a tasklet to complete before we drop
our forcewake, ensuring the system is ready for rc6 before we let it
possibly sleep.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180522101937.7738-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/i915_gem.h | 6 ++++++
drivers/gpu/drm/i915/intel_lrc.c | 11 ++++++++++-
2 files changed, 16 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -82,4 +82,10 @@ static inline void __tasklet_disable_syn
tasklet_unlock_wait(t);
}
+static inline void __tasklet_enable_sync_once(struct tasklet_struct *t)
+{
+ if (atomic_dec_return(&t->count) == 0)
+ tasklet_kill(t);
+}
+
#endif /* __I915_GEM_H__ */
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -2017,7 +2017,16 @@ static void execlists_reset(struct intel
static void execlists_reset_finish(struct intel_engine_cs *engine)
{
- tasklet_enable(&engine->execlists.tasklet);
+ /*
+ * Flush the tasklet while we still have the forcewake to be sure
+ * that it is not allowed to sleep before we restart and reload a
+ * context.
+ *
+ * As before (with execlists_reset_prepare) we rely on the caller
+ * serialising multiple attempts to reset so that we know that we
+ * are the only one manipulating tasklet state.
+ */
+ __tasklet_enable_sync_once(&engine->execlists.tasklet);
GEM_TRACE("%s\n", engine->name);
}