tmp = navi10_ih_rb_cntl(ih, tmp);
        if (ih == &adev->irq.ih)
                tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, RPTR_REARM, !!adev->irq.msi_enabled);
-       if (ih == &adev->irq.ih1) {
-               tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, WPTR_OVERFLOW_ENABLE, 0);
+       if (ih == &adev->irq.ih1)
                tmp = REG_SET_FIELD(tmp, IH_RB_CNTL, RB_FULL_DRAIN_ENABLE, 1);
-       }
 
        if (amdgpu_sriov_vf(adev) && amdgpu_sriov_reg_indirect_ih(adev)) {
                if (psp_reg_program(&adev->psp, ih_regs->psp_reg_id, tmp)) {
 {
        struct amdgpu_ih_ring *ih[] = {&adev->irq.ih, &adev->irq.ih1, &adev->irq.ih2};
        u32 ih_chicken;
-       u32 tmp;
        int ret;
        int i;
 
        adev->nbio.funcs->ih_doorbell_range(adev, ih[0]->use_doorbell,
                                            ih[0]->doorbell_index);
 
-       tmp = RREG32_SOC15(OSSSYS, 0, mmIH_STORM_CLIENT_LIST_CNTL);
-       tmp = REG_SET_FIELD(tmp, IH_STORM_CLIENT_LIST_CNTL,
-                           CLIENT18_IS_STORM_CLIENT, 1);
-       WREG32_SOC15(OSSSYS, 0, mmIH_STORM_CLIENT_LIST_CNTL, tmp);
-
-       tmp = RREG32_SOC15(OSSSYS, 0, mmIH_INT_FLOOD_CNTL);
-       tmp = REG_SET_FIELD(tmp, IH_INT_FLOOD_CNTL, FLOOD_CNTL_ENABLE, 1);
-       WREG32_SOC15(OSSSYS, 0, mmIH_INT_FLOOD_CNTL, tmp);
-
        pci_set_master(adev->pdev);
 
        /* enable interrupts */
        u32 wptr, tmp;
        struct amdgpu_ih_regs *ih_regs;
 
-       wptr = le32_to_cpu(*ih->wptr_cpu);
-       ih_regs = &ih->ih_regs;
+       if (ih == &adev->irq.ih) {
+               /* Only ring0 supports writeback. On other rings fall back
+                * to register-based code with overflow checking below.
+                */
+               wptr = le32_to_cpu(*ih->wptr_cpu);
 
-       if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
-               goto out;
+               if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
+                       goto out;
+       }
 
+       ih_regs = &ih->ih_regs;
+
+       /* Double check that the overflow wasn't already cleared. */
        wptr = RREG32_NO_KIQ(ih_regs->ih_rb_wptr);
        if (!REG_GET_FIELD(wptr, IH_RB_WPTR, RB_OVERFLOW))
                goto out;
                              struct amdgpu_irq_src *source,
                              struct amdgpu_iv_entry *entry)
 {
-       uint32_t wptr = cpu_to_le32(entry->src_data[0]);
-
        switch (entry->ring_id) {
        case 1:
-               *adev->irq.ih1.wptr_cpu = wptr;
                schedule_work(&adev->irq.ih1_work);
                break;
        case 2:
-               *adev->irq.ih2.wptr_cpu = wptr;
                schedule_work(&adev->irq.ih2_work);
                break;
        default: break;