intel_uncore_forcewake_reset() does forcewake puts and gets as such we need to make sure that no-one tries to access the PUNIT->PMIC bus (on systems where this bus is shared) while it runs, otherwise bad things happen. Normally this is taken care of by the i915_pmic_bus_access_notifier() which does an intel_uncore_forcewake_get(FORCEWAKE_ALL) when some other driver tries to access the PMIC bus, so that later forcewake gets are no-ops (for the duration of the bus access). But intel_uncore_forcewake_reset gets called in 3 cases: 1) Before registering the pmic_bus_access_notifier 2) After unregistering the pmic_bus_access_notifier 3) To reset forcewake state on a GPU reset In all 3 cases the i915_pmic_bus_access_notifier() protection is insufficient. This commit fixes the pmic bus access race this causes by making intel_uncore_forcewake_reset() call iosf_mbi_punit_acquire() (and iosf_mbi_punit_release() when done). Note that iosf_mbi_punit_acquire() locks a mutex and thus intel_uncore_forcewake_reset() may sleep after this commit. I've checked all callers and they all already take other mutexes, so this is not a problem. Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/gpu/drm/i915/intel_uncore.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 882cf7187a57..0fb829cc1cbd 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -252,6 +252,9 @@ static void intel_uncore_forcewake_reset(struct drm_i915_private *dev_priv, int retry_count = 100; enum forcewake_domains fw, active_domains; + /* Acquire the PUNIT->PMIC bus before modifying forcewake settings */ + iosf_mbi_punit_acquire(); + /* Hold uncore.lock across reset to prevent any register access * with forcewake not set correctly. Wait until all pending * timers are run before holding. @@ -308,6 +311,7 @@ static void intel_uncore_forcewake_reset(struct drm_i915_private *dev_priv, assert_forcewakes_inactive(dev_priv); spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); + iosf_mbi_punit_release(); } static u64 gen9_edram_size(struct drm_i915_private *dev_priv) -- 2.12.2 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
