The DMC typifies the worst example of firmware: it overrides system behaviour and is fubar. When no displays are active, the DMC appears to continually toggle its control register trying to change display power states. This in turn has the side effect of slowing down the GT by a few orders of magntidue, making headless operations intolerably slow. This seems to affect all machines with dmc (so a byproduct of the dmc code itself being shared) and severely limits throughput on the CI bxt and triggers the watchdog for incomplete tests. Altenative suggestion is to blacklist all DMC firmware until it is fixed. References: https://bugs.freedesktop.org/show_bug.cgi?id=100572 Testcase: igt/gem_exec_nop/headless Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Imre Deak <imre.deak@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem.c | 3 +++ drivers/gpu/drm/i915/i915_gem_request.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index ba72a4bdaa78..e3236c1d44f0 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3331,6 +3331,9 @@ i915_gem_idle_work_handler(struct work_struct *work) intel_engines_mark_idle(dev_priv); i915_gem_timelines_mark_idle(dev_priv); + if (dev_priv->csr.dmc_payload) + intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET); + GEM_BUG_ON(!dev_priv->gt.awake); dev_priv->gt.awake = false; rearm_hangcheck = false; diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c index 813a3b546d6e..3c8ebdb5b0b4 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.c +++ b/drivers/gpu/drm/i915/i915_gem_request.c @@ -254,6 +254,9 @@ static void mark_busy(struct drm_i915_private *i915) intel_runtime_pm_get_noresume(i915); i915->gt.awake = true; + if (i915->csr.dmc_payload) + intel_display_power_get(i915, POWER_DOMAIN_MODESET); + intel_enable_gt_powersave(i915); i915_update_gfx_val(i915); if (INTEL_GEN(i915) >= 6) -- 2.14.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
