3.2.71-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Alexey Brodkin <Alexey.Brodkin@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
Cc: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
Cc: arc-linux-dev@xxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: David Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.2:
- Adjust context, indentation
- Normal and extended descriptors are allocated in the same place here]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- 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;
--- 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
{
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
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++;
}
--- 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 dm
{
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 dm
{
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++;
}
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -441,19 +441,17 @@ static void init_dma_desc_rings(struct n
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__);
--
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