+
+ /*
+ * These (at least TxRingAddr) need to be configured after the
+ * corresponding bits in CpCmd are enabled. Datasheet v1.6 ยง6.33
+ * (C+ Command Register) recommends that these and more be configured
+ * *after* the [RT]xEnable bits in CpCmd are set. And on some hardware
+ * it's been observed that the TxRingAddr is actually reset to garbage
+ * when C+ mode Tx is enabled in CpCmd.
+ */
+ cpw32_f(HiTxRingAddr, 0);
+ cpw32_f(HiTxRingAddr + 4, 0);
+
+ ring_dma = cp->ring_dma;
+ cpw32_f(RxRingAddr, ring_dma & 0xffffffff);
+ cpw32_f(RxRingAddr + 4, (ring_dma >> 16) >> 16);
+
+ ring_dma += sizeof(struct cp_desc) * CP_RX_RING_SIZE;
+ cpw32_f(TxRingAddr, ring_dma & 0xffffffff);
+ cpw32_f(TxRingAddr + 4, (ring_dma >> 16) >> 16);
+
+ /*
+ * Strictly speaking, the datasheet says this should be enabled
+ * *before* setting the descriptor addresses. But what, then, would
+ * prevent it from doing DMA to random unconfigured addresses?
+ * This variant appears to work fine.
+ */