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authorAlexey Brodkin <Alexey.Brodkin@synopsys.com>2015-06-24 11:47:41 +0300
committerZefan Li <lizefan@huawei.com>2015-10-22 09:20:06 +0800
commit176a2eacd65fbc3b3d911605a83d3262770fc213 (patch)
tree88b9834660f5e3bfb99116356e663a9c53ad02aa
parente2b3a182f87e27d44bc95dcb1d005bc4191ea7e1 (diff)
downloadlwn-176a2eacd65fbc3b3d911605a83d3262770fc213.tar.gz
lwn-176a2eacd65fbc3b3d911605a83d3262770fc213.zip
stmmac: troubleshoot unexpected bits in des0 & des1
commit f1590670ce069eefeb93916391a67643e6ad1630 upstream. 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: David Miller <davem@davemloft.net> Signed-off-by: David S. Miller <davem@davemloft.net> [lizf: Backported to 3.4: - adjust contest - adjust allocations in init_dma_desc_rings()] Signed-off-by: Zefan Li <lizefan@huawei.com>
-rw-r--r--drivers/net/ethernet/stmicro/stmmac/descs.h2
-rw-r--r--drivers/net/ethernet/stmicro/stmmac/enh_desc.c4
-rw-r--r--drivers/net/ethernet/stmicro/stmmac/norm_desc.c4
-rw-r--r--drivers/net/ethernet/stmicro/stmmac/stmmac_main.c18
4 files changed, 16 insertions, 12 deletions
diff --git a/drivers/net/ethernet/stmicro/stmmac/descs.h b/drivers/net/ethernet/stmicro/stmmac/descs.h
index 9820ec842cc0..e93a0bf128be 100644
--- a/drivers/net/ethernet/stmicro/stmmac/descs.h
+++ b/drivers/net/ethernet/stmicro/stmmac/descs.h
@@ -153,6 +153,8 @@ 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 ad1b627f8ec2..e0db6f66e92e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/enh_desc.c
@@ -232,6 +232,7 @@ static void enh_desc_init_rx_desc(struct dma_desc *p, unsigned int ring_size,
{
int i;
for (i = 0; i < ring_size; i++) {
+ p->des01.all_flags = 0;
p->des01.erx.own = 1;
p->des01.erx.buffer1_size = BUF_SIZE_8KiB - 1;
@@ -248,7 +249,7 @@ static void enh_desc_init_tx_desc(struct dma_desc *p, unsigned int ring_size)
int i;
for (i = 0; i < ring_size; i++) {
- p->des01.etx.own = 0;
+ p->des01.all_flags = 0;
ehn_desc_tx_set_on_ring_chain(p, (i == ring_size - 1));
p++;
}
@@ -271,6 +272,7 @@ static void enh_desc_set_tx_owner(struct dma_desc *p)
static void enh_desc_set_rx_owner(struct dma_desc *p)
{
+ p->des01.all_flags = 0;
p->des01.erx.own = 1;
}
diff --git a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
index 25953bb45a73..9703340c3115 100644
--- a/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/norm_desc.c
@@ -126,6 +126,7 @@ static void ndesc_init_rx_desc(struct dma_desc *p, unsigned int ring_size,
{
int i;
for (i = 0; i < ring_size; i++) {
+ p->des01.all_flags = 0;
p->des01.rx.own = 1;
p->des01.rx.buffer1_size = BUF_SIZE_2KiB - 1;
@@ -141,7 +142,7 @@ static void ndesc_init_tx_desc(struct dma_desc *p, unsigned int ring_size)
{
int i;
for (i = 0; i < ring_size; i++) {
- p->des01.tx.own = 0;
+ p->des01.all_flags = 0;
ndesc_tx_set_on_ring_chain(p, (i == (ring_size - 1)));
p++;
}
@@ -164,6 +165,7 @@ static void ndesc_set_tx_owner(struct dma_desc *p)
static void ndesc_set_rx_owner(struct dma_desc *p)
{
+ p->des01.all_flags = 0;
p->des01.rx.own = 1;
}
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 9bdfaba4e308..88c8645e2f52 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -424,19 +424,17 @@ static void init_dma_desc_rings(struct net_device *dev)
priv->rx_skbuff =
kmalloc(sizeof(struct sk_buff *) * rxsize, GFP_KERNEL);
priv->dma_rx =
- (struct dma_desc *)dma_alloc_coherent(priv->device,
- rxsize *
- sizeof(struct dma_desc),
- &priv->dma_rx_phy,
- GFP_KERNEL);
+ (struct dma_desc *)dma_zalloc_coherent(priv->device, rxsize *
+ sizeof(struct dma_desc),
+ &priv->dma_rx_phy,
+ GFP_KERNEL);
priv->tx_skbuff = kmalloc(sizeof(struct sk_buff *) * txsize,
GFP_KERNEL);
priv->dma_tx =
- (struct dma_desc *)dma_alloc_coherent(priv->device,
- txsize *
- sizeof(struct dma_desc),
- &priv->dma_tx_phy,
- GFP_KERNEL);
+ (struct dma_desc *)dma_zalloc_coherent(priv->device, txsize *
+ sizeof(struct dma_desc),
+ &priv->dma_tx_phy,
+ GFP_KERNEL);
if ((priv->dma_rx == NULL) || (priv->dma_tx == NULL)) {
pr_err("%s:ERROR allocating the DMA Tx/Rx desc\n", __func__);