stmmac: troubleshoot unexpected bits in des0 & des1

Current implementation of descriptor init procedure only takes
care about setting/clearing ownership flag in "des0"/"des1"
fields while it is perfectly possible to get unexpected bits
set because of the following factors:

 [1] On driver probe underlying memory allocated with
     dma_alloc_coherent() might not be zeroed and so
     it will be filled with garbage.

 [2] During driver operation some bits could be set by SD/MMC
     controller (for example error flags etc).

And unexpected and/or randomly set flags in "des0"/"des1"
fields may lead to unpredictable behavior of GMAC DMA block.

This change addresses both items above with:

 [1] Use of dma_zalloc_coherent() instead of simple
     dma_alloc_coherent() to make sure allocated memory is
     zeroed. That shouldn't affect performance because
     this allocation only happens once on driver probe.

 [2] Do explicit zeroing of both "des0" and "des1" fields
     of all buffer descriptors during initialization of
     DMA transfer.

And while at it fixed identation of dma_free_coherent()
counterpart as well.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: arc-linux-dev@synopsys.com
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/stmicro/stmmac/descs.h b/drivers/net/ethernet/stmicro/stmmac/descs.h
index ad399603801800267d2704640d40251927a93396..799c2929c5365792ecf83682ac4064e24669d023 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/descs.h
+++ b/drivers/net/ethernet/stmicro/stmmac/descs.h
@@ -158,6 +158,8 @@ struct dma_desc {
                        u32 buffer2_size:13;
                        u32 reserved4:3;
                } etx;          /* -- enhanced -- */
+
+               u64 all_flags;
        } des01;
        unsigned int des2;
        unsigned int des3;

diff --git a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
index 1e2bcf5f89e13837b03bec3da31b48113441eb47..7d944449f5eff9b16c4d7cf633f0cd4d2eb9b879 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
@@ -240,6 +240,7 @@ static int enh_desc_get_rx_status(void *data, struct stmmac_extra_stats *x,
 static void enh_desc_init_rx_desc(struct dma_desc *p, int disable_rx_ic,
                                  int mode, int end)
 {
+       p->des01.all_flags = 0;
        p->des01.erx.own = 1;
        p->des01.erx.buffer1_size = BUF_SIZE_8KiB - 1;
 
@@ -254,7 +255,7 @@ static void enh_desc_init_rx_desc(struct dma_desc *p, int disable_rx_ic,
 
 static void enh_desc_init_tx_desc(struct dma_desc *p, int mode, int end)
 {
-       p->des01.etx.own = 0;
+       p->des01.all_flags = 0;
        if (mode == STMMAC_CHAIN_MODE)
                ehn_desc_tx_set_on_chain(p, end);
        else

diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
index 35ad4f427ae2b33120edabedb4d9b0aee7233abf..48c3456445b282597b89f73cd39b78d5e5caf982 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
@@ -123,6 +123,7 @@ static int ndesc_get_rx_status(void *data, struct stmmac_extra_stats *x,
 static void ndesc_init_rx_desc(struct dma_desc *p, int disable_rx_ic, int mode,
                               int end)
 {
+       p->des01.all_flags = 0;
        p->des01.rx.own = 1;
        p->des01.rx.buffer1_size = BUF_SIZE_2KiB - 1;
 
@@ -137,7 +138,7 @@ static void ndesc_init_rx_desc(struct dma_desc *p, int disable_rx_ic, int mode,
 
 static void ndesc_init_tx_desc(struct dma_desc *p, int mode, int end)
 {
-       p->des01.tx.own = 0;
+       p->des01.all_flags = 0;
        if (mode == STMMAC_CHAIN_MODE)
                ndesc_tx_set_on_chain(p, end);
        else

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 2c5ce2baca8712790d51096a53868b84466f7dde..2e299e0949d7ea263489bca6d0d3233dc7ddbc29 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1189,41 +1189,41 @@ static int alloc_dma_desc_resources(struct stmmac_priv *priv)
                goto err_tx_skbuff;
 
        if (priv->extend_desc) {
-               priv->dma_erx = dma_alloc_coherent(priv->device, rxsize *
-                                                  sizeof(struct
-                                                         dma_extended_desc),
-                                                  &priv->dma_rx_phy,
-                                                  GFP_KERNEL);
+               priv->dma_erx = dma_zalloc_coherent(priv->device, rxsize *
+                                                   sizeof(struct
+                                                          dma_extended_desc),
+                                                   &priv->dma_rx_phy,
+                                                   GFP_KERNEL);
                if (!priv->dma_erx)
                        goto err_dma;
 
-               priv->dma_etx = dma_alloc_coherent(priv->device, txsize *
-                                                  sizeof(struct
-                                                         dma_extended_desc),
-                                                  &priv->dma_tx_phy,
-                                                  GFP_KERNEL);
+               priv->dma_etx = dma_zalloc_coherent(priv->device, txsize *
+                                                   sizeof(struct
+                                                          dma_extended_desc),
+                                                   &priv->dma_tx_phy,
+                                                   GFP_KERNEL);
                if (!priv->dma_etx) {
                        dma_free_coherent(priv->device, priv->dma_rx_size *
-                                       sizeof(struct dma_extended_desc),
-                                       priv->dma_erx, priv->dma_rx_phy);
+                                         sizeof(struct dma_extended_desc),
+                                         priv->dma_erx, priv->dma_rx_phy);
                        goto err_dma;
                }
        } else {
-               priv->dma_rx = dma_alloc_coherent(priv->device, rxsize *
-                                                 sizeof(struct dma_desc),
-                                                 &priv->dma_rx_phy,
-                                                 GFP_KERNEL);
+               priv->dma_rx = dma_zalloc_coherent(priv->device, rxsize *
+                                                  sizeof(struct dma_desc),
+                                                  &priv->dma_rx_phy,
+                                                  GFP_KERNEL);
                if (!priv->dma_rx)
                        goto err_dma;
 
-               priv->dma_tx = dma_alloc_coherent(priv->device, txsize *
-                                                 sizeof(struct dma_desc),
-                                                 &priv->dma_tx_phy,
-                                                 GFP_KERNEL);
+               priv->dma_tx = dma_zalloc_coherent(priv->device, txsize *
+                                                  sizeof(struct dma_desc),
+                                                  &priv->dma_tx_phy,
+                                                  GFP_KERNEL);
                if (!priv->dma_tx) {
                        dma_free_coherent(priv->device, priv->dma_rx_size *
-                                       sizeof(struct dma_desc),
-                                       priv->dma_rx, priv->dma_rx_phy);
+                                         sizeof(struct dma_desc),
+                                         priv->dma_rx, priv->dma_rx_phy);
                        goto err_dma;
                }
        }