drm/i915: Apply missed interrupt after reset w/a to all ringbuffer gen

Having completed a test run of gem_eio across all machines in CI we also
observe the phenomenon (of lost interrupts after resetting the GPU) on
gen3 machines as well as the previously sighted gen6/gen7. Let's apply
the same HWSTAM workaround that was effective for gen6+ for all, as
although we haven't seen the same failure on gen4/5 it seems prudent to
keep the code the same.

As a consequence we can remove the extra setting of HWSTAM and apply the
register from a single site.

v2: Delazy and move the HWSTAM into its own function
v3: Mask off all HWSP writes on driver unload and engine cleanup.
v4: And what about the physical hwsp?
v5: No, engine->init_hw() is not called from driver_init_hw(), don't be
daft. Really scrub HWSTAM as early as we can in driver_init_mmio()
v6: Rename set_hwsp as it was setting the mask not the hwsp register.
v7: Ville pointed out that although vcs(bsd) was introduced for g4x/ilk,
per-engine HWSTAM was not introduced until gen6!

References: https://bugs.freedesktop.org/show_bug.cgi?id=108735
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181218102712.11058-1-chris@chris-wilson.co.uk

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 66d0ad9c36c4..561b474cbab1 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -261,6 +261,31 @@ static void __sprint_engine_name(char *name, const struct engine_info *info)
 			 info->instance) >= INTEL_ENGINE_CS_MAX_NAME);
 }
 
+void intel_engine_set_hwsp_writemask(struct intel_engine_cs *engine, u32 mask)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+	i915_reg_t hwstam;
+
+	/*
+	 * Though they added more rings on g4x/ilk, they did not add
+	 * per-engine HWSTAM until gen6.
+	 */
+	if (INTEL_GEN(dev_priv) < 6 && engine->class != RENDER_CLASS)
+		return;
+
+	hwstam = RING_HWSTAM(engine->mmio_base);
+	if (INTEL_GEN(dev_priv) >= 3)
+		I915_WRITE(hwstam, mask);
+	else
+		I915_WRITE16(hwstam, mask);
+}
+
+static void intel_engine_sanitize_mmio(struct intel_engine_cs *engine)
+{
+	/* Mask off all writes into the unknown HWSP */
+	intel_engine_set_hwsp_writemask(engine, ~0u);
+}
+
 static int
 intel_engine_setup(struct drm_i915_private *dev_priv,
 		   enum intel_engine_id id)
@@ -312,6 +337,9 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
 
 	ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);
 
+	/* Scrub mmio state on takeover */
+	intel_engine_sanitize_mmio(engine);
+
 	dev_priv->engine_class[info->class][info->instance] = engine;
 	dev_priv->engine[id] = engine;
 	return 0;
@@ -495,6 +523,9 @@ void intel_engine_setup_common(struct intel_engine_cs *engine)
 
 static void cleanup_status_page(struct intel_engine_cs *engine)
 {
+	/* Prevent writes into HWSP after returning the page to the system */
+	intel_engine_set_hwsp_writemask(engine, ~0u);
+
 	if (HWS_NEEDS_PHYSICAL(engine->i915)) {
 		void *addr = fetch_and_zero(&engine->status_page.page_addr);