Commit 86a88cf3 authored by Alexey Brodkin's avatar Alexey Brodkin Committed by Luis Henriques

stmmac: troubleshoot unexpected bits in des0 & des1

commit f1590670 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: default avatarAlexey 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: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 57932240
......@@ -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;
......
......@@ -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
......
......@@ -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
......
......@@ -1142,41 +1142,41 @@ 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;
}
}
......
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