From: Fabrice Gasnier <fabrice.gasn...@st.com>

The RDES0 register can be read several times while doing RX of a
packet.
This patch slightly improves RX path performance by reading rdes0
once for two operation: check rx owner, get rx status bits.

Signed-off-by: Fabrice Gasnier <fabrice.gasn...@st.com>
Acked-by: Giuseppe Cavallaro <peppe.cavall...@st.com>
Signed-off-by: Alexandre TORGUE <alexandre.tor...@st.com>

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h 
b/drivers/net/ethernet/stmicro/stmmac/common.h
index 09291af..3ba268e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -238,10 +238,11 @@ struct stmmac_extra_stats {
 
 /* Rx IPC status */
 enum rx_frame_status {
-       good_frame = 0,
-       discard_frame = 1,
-       csum_none = 2,
-       llc_snap = 4,
+       good_frame = 0x0,
+       discard_frame = 0x1,
+       csum_none = 0x2,
+       llc_snap = 0x4,
+       dma_own = 0x8,
 };
 
 enum dma_irq_status {
@@ -356,7 +357,6 @@ struct stmmac_desc_ops {
        /* Get the buffer size from the descriptor */
        int (*get_tx_len) (struct dma_desc *p);
        /* Handle extra events on specific interrupts hw dependent */
-       int (*get_rx_owner) (struct dma_desc *p);
        void (*set_rx_owner) (struct dma_desc *p);
        /* Get the receive frame size */
        int (*get_rx_frame_len) (struct dma_desc *p, int rx_coe_type);
diff --git a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c 
b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
index 716b807..1a2fce9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
@@ -186,6 +186,9 @@ static int enh_desc_get_rx_status(void *data, struct 
stmmac_extra_stats *x,
        unsigned int rdes0 = p->des0;
        int ret = good_frame;
 
+       if (unlikely(rdes0 & RDES0_OWN))
+               return dma_own;
+
        if (unlikely(rdes0 & RDES0_ERROR_SUMMARY)) {
                if (unlikely(rdes0 & RDES0_DESCRIPTOR_ERROR)) {
                        x->rx_desc++;
@@ -272,11 +275,6 @@ static int enh_desc_get_tx_owner(struct dma_desc *p)
        return (p->des0 & ETDES0_OWN) >> 31;
 }
 
-static int enh_desc_get_rx_owner(struct dma_desc *p)
-{
-       return (p->des0 & RDES0_OWN) >> 31;
-}
-
 static void enh_desc_set_tx_owner(struct dma_desc *p)
 {
        p->des0 |= ETDES0_OWN;
@@ -402,7 +400,6 @@ const struct stmmac_desc_ops enh_desc_ops = {
        .init_rx_desc = enh_desc_init_rx_desc,
        .init_tx_desc = enh_desc_init_tx_desc,
        .get_tx_owner = enh_desc_get_tx_owner,
-       .get_rx_owner = enh_desc_get_rx_owner,
        .release_tx_desc = enh_desc_release_tx_desc,
        .prepare_tx_desc = enh_desc_prepare_tx_desc,
        .clear_tx_ic = enh_desc_clear_tx_ic,
diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c 
b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
index 460c573..5a91932 100644
--- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
@@ -82,6 +82,9 @@ static int ndesc_get_rx_status(void *data, struct 
stmmac_extra_stats *x,
        unsigned int rdes0 = p->des0;
        struct net_device_stats *stats = (struct net_device_stats *)data;
 
+       if (unlikely(rdes0 & RDES0_OWN))
+               return dma_own;
+
        if (unlikely(!(rdes0 & RDES0_LAST_DESCRIPTOR))) {
                pr_warn("%s: Oversized frame spanned multiple buffers\n",
                        __func__);
@@ -155,11 +158,6 @@ static int ndesc_get_tx_owner(struct dma_desc *p)
        return (p->des0 & TDES0_OWN) >> 31;
 }
 
-static int ndesc_get_rx_owner(struct dma_desc *p)
-{
-       return (p->des0 & RDES0_OWN) >> 31;
-}
-
 static void ndesc_set_tx_owner(struct dma_desc *p)
 {
        p->des0 |= TDES0_OWN;
@@ -277,7 +275,6 @@ const struct stmmac_desc_ops ndesc_ops = {
        .init_rx_desc = ndesc_init_rx_desc,
        .init_tx_desc = ndesc_init_tx_desc,
        .get_tx_owner = ndesc_get_tx_owner,
-       .get_rx_owner = ndesc_get_rx_owner,
        .release_tx_desc = ndesc_release_tx_desc,
        .prepare_tx_desc = ndesc_prepare_tx_desc,
        .clear_tx_ic = ndesc_clear_tx_ic,
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c 
b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 0194a8f..796d7c6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2205,7 +2205,11 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit)
                else
                        p = priv->dma_rx + entry;
 
-               if (priv->hw->desc->get_rx_owner(p))
+               /* read the status of the incoming frame */
+               status = priv->hw->desc->rx_status(&priv->dev->stats,
+                                                  &priv->xstats, p);
+               /* check if managed by the DMA otherwise go ahead */
+               if (unlikely(status & dma_own))
                        break;
 
                count++;
@@ -2218,9 +2222,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit)
                else
                        prefetch(priv->dma_rx + next_entry);
 
-               /* read the status of the incoming frame */
-               status = priv->hw->desc->rx_status(&priv->dev->stats,
-                                                  &priv->xstats, p);
                if ((priv->extend_desc) && (priv->hw->desc->rx_extended_status))
                        priv->hw->desc->rx_extended_status(&priv->dev->stats,
                                                           &priv->xstats,
-- 
1.9.1

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