* driver threads, but also with hardware/firmware agents. A dedicated
* locking register is used.
*/
- if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70))
+ if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) {
+ /*
+ * The steering control and semaphore registers are inside an
+ * "always on" power domain with respect to RC6. However there
+ * are some issues if higher-level platform sleep states are
+ * entering/exiting at the same time these registers are
+ * accessed. Grabbing GT forcewake and holding it over the
+ * entire lock/steer/unlock cycle ensures that those sleep
+ * states have been fully exited before we access these
+ * registers. This wakeref will be released in the unlock
+ * routine.
+ *
+ * This is expected to become a formally documented/numbered
+ * workaround soon.
+ */
+ intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_GT);
+
err = wait_for(intel_uncore_read_fw(gt->uncore,
MTL_STEER_SEMAPHORE) == 0x1, 100);
+ }
/*
* Even on platforms with a hardware lock, we'll continue to grab
{
spin_unlock_irqrestore(>->mcr_lock, flags);
- if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70))
+ if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70)) {
intel_uncore_write_fw(gt->uncore, MTL_STEER_SEMAPHORE, 0x1);
+
+ intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_GT);
+ }
}
/**