iwlwifi: refactor rx register initialization

The patch adds HW bug W/A FH_RCSR_CHNL0_RX_IGNORE_RXF_EMPTY so that we
can enable again interrupt coalescing. It also uses named constants for
open code.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-fh.h

@@ -247,8 +247,8 @@
 #define FH_RCSR_CHNL0_RX_CONFIG_RBDBC_SIZE_MSK (0x00F00000) /* bits 20-23 */
 #define FH_RCSR_CHNL0_RX_CONFIG_DMA_CHNL_EN_MSK (0xC0000000) /* bits 30-31*/
 
-#define FH_RCSR_RX_CONFIG_RBDCB_SIZE_BITSHIFT	(20)
-#define FH_RCSR_RX_CONFIG_REG_IRQ_RBTH_BITSHIFT	(4)
+#define FH_RCSR_RX_CONFIG_RBDCB_SIZE_POS	(20)
+#define FH_RCSR_RX_CONFIG_REG_IRQ_RBTH_POS	(4)
 #define RX_RB_TIMEOUT	(0x10)
 
 #define FH_RCSR_RX_CONFIG_CHNL_EN_PAUSE_VAL         (0x00000000)
@@ -260,6 +260,7 @@
 #define FH_RCSR_RX_CONFIG_REG_VAL_RB_SIZE_12K   (0x00020000)
 #define FH_RCSR_RX_CONFIG_REG_VAL_RB_SIZE_16K   (0x00030000)
 
+#define FH_RCSR_CHNL0_RX_IGNORE_RXF_EMPTY              (0x00000004)
 #define FH_RCSR_CHNL0_RX_CONFIG_IRQ_DEST_NO_INT_VAL    (0x00000000)
 #define FH_RCSR_CHNL0_RX_CONFIG_IRQ_DEST_INT_HOST_VAL  (0x00001000)
 

drivers/net/wireless/iwlwifi/iwl-rx.c

@@ -376,7 +376,9 @@ int iwl_rx_init(struct iwl_priv *priv, struct iwl_rx_queue *rxq)
 {
 	int ret;
 	unsigned long flags;
-	unsigned int rb_size;
+	u32 rb_size;
+	const u32 rfdnlog = RX_QUEUE_SIZE_LOG; /* 256 RBDs */
+	const u32 rb_timeout = 0; /* FIXME: RX_RB_TIMEOUT why this stalls RX */
 
 	spin_lock_irqsave(&priv->lock, flags);
 	ret = iwl_grab_nic_access(priv);
@@ -398,26 +400,32 @@ int iwl_rx_init(struct iwl_priv *priv, struct iwl_rx_queue *rxq)
 
 	/* Tell device where to find RBD circular buffer in DRAM */
 	iwl_write_direct32(priv, FH_RSCSR_CHNL0_RBDCB_BASE_REG,
-			   rxq->dma_addr >> 8);
+			   (u32)(rxq->dma_addr >> 8));
 
 	/* Tell device where in DRAM to update its Rx status */
 	iwl_write_direct32(priv, FH_RSCSR_CHNL0_STTS_WPTR_REG,
 			   (priv->shared_phys + priv->rb_closed_offset) >> 4);
 
-	/* Enable Rx DMA, enable host interrupt, Rx buffer size 4k, 256 RBDs */
+	/* Enable Rx DMA
+	 * FH_RCSR_CHNL0_RX_IGNORE_RXF_EMPTY is set becuase of HW bug in
+	 *      the credit mechanism in 5000 HW RX FIFO
+	 * Direct rx interrupts to hosts
+	 * Rx buffer size 4 or 8k
+	 * RB timeout 0x10
+	 * 256 RBDs
+	 */
 	iwl_write_direct32(priv, FH_MEM_RCSR_CHNL0_CONFIG_REG,
 			   FH_RCSR_RX_CONFIG_CHNL_EN_ENABLE_VAL |
+			   FH_RCSR_CHNL0_RX_IGNORE_RXF_EMPTY |
 			   FH_RCSR_CHNL0_RX_CONFIG_IRQ_DEST_INT_HOST_VAL |
-			   rb_size |
-			     /* 0x10 << 4 | */
-			   (RX_QUEUE_SIZE_LOG <<
-			      FH_RCSR_RX_CONFIG_RBDCB_SIZE_BITSHIFT));
-
-	/*
-	 * iwl_write32(priv,CSR_INT_COAL_REG,0);
-	 */
+			   rb_size|
+			   (rb_timeout << FH_RCSR_RX_CONFIG_REG_IRQ_RBTH_POS)|
+			   (rfdnlog << FH_RCSR_RX_CONFIG_RBDCB_SIZE_POS));
 
 	iwl_release_nic_access(priv);
+
+	iwl_write32(priv, CSR_INT_COALESCING, 0x40);
+
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	return 0;