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Message-Id: <1435135661-24359-1-git-send-email-abrodkin@synopsys.com>
Date: Wed, 24 Jun 2015 11:47:41 +0300
From: Alexey Brodkin <Alexey.Brodkin@...opsys.com>
To: netdev@...r.kernel.org
Cc: Alexey Brodkin <Alexey.Brodkin@...opsys.com>,
Giuseppe Cavallaro <peppe.cavallaro@...com>,
arc-linux-dev@...opsys.com, linux-kernel@...r.kernel.org,
stable@...r.kernel.org, David Miller <davem@...emloft.net>
Subject: [PATCH v3] 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@...opsys.com>
Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>
Cc: arc-linux-dev@...opsys.com
Cc: linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org
Cc: David Miller <davem@...emloft.net>
---
Changes compared to v2:
* Fixed identation of dma_zalloc_coherent() parameters
* Fixed identation of dma_free_coherent() counterpart
Changes compared to v1:
* Use dma_zalloc_coherent() instead of dma_alloc_coherent()
on probing to make sure no garbage appears in buffer descriptors
---
drivers/net/ethernet/stmicro/stmmac/descs.h | 2 ++
drivers/net/ethernet/stmicro/stmmac/enh_desc.c | 3 +-
drivers/net/ethernet/stmicro/stmmac/norm_desc.c | 3 +-
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 44 +++++++++++------------
4 files changed, 28 insertions(+), 24 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/descs.h b/drivers/net/ethernet/stmicro/stmmac/descs.h
index ad39960..799c292 100644
--- 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 1e2bcf5..7d94444 100644
--- 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 35ad4f4..48c3456 100644
--- 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 a515673..50f7a7a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1195,41 +1195,41 @@ 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;
}
}
--
2.4.2
--
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