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authorRadu Rendec <radu.rendec@gmail.com>2018-01-04 18:18:13 +0000
committerWolfram Sang <wsa@the-dreams.de>2018-01-15 21:02:43 +0100
commit5cd5f0bb0d9c32876b3d86b70fb45da10d028be7 (patch)
tree198e1c234751afa5b92467bcfb11f2143875675f /drivers/i2c
parent38a99bd7730efdd0ca6ce2531a2761778fca3293 (diff)
i2c: ismt: 16-byte align the DMA buffer address
Use only a portion of the data buffer for DMA transfers, which is always 16-byte aligned. This makes the DMA buffer address 16-byte aligned and compensates for spurious hardware parity errors that may appear when the DMA buffer address is not 16-byte aligned. The data buffer is enlarged in order to accommodate any possible 16-byte alignment offset and changes the DMA code to only use a portion of the data buffer, which is 16-byte aligned. The symptom of the hardware issue is the same as the one addressed in v3.12-rc2-5-gbf41691 and manifests by transfers failing with EIO, with bit 9 being set in the ERRSTS register. Signed-off-by: Radu Rendec <radu.rendec@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-ismt.c37
1 files changed, 19 insertions, 18 deletions
diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index 45ad9b847c58..0d1c3ec8cb40 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -172,7 +172,7 @@ struct ismt_priv {
dma_addr_t io_rng_dma; /* descriptor HW base addr */
u8 head; /* ring buffer head pointer */
struct completion cmp; /* interrupt completion */
- u8 dma_buffer[I2C_SMBUS_BLOCK_MAX + 1]; /* temp R/W data buffer */
+ u8 buffer[I2C_SMBUS_BLOCK_MAX + 16]; /* temp R/W data buffer */
};
/**
@@ -320,7 +320,7 @@ static int ismt_process_desc(const struct ismt_desc *desc,
struct ismt_priv *priv, int size,
char read_write)
{
- u8 *dma_buffer = priv->dma_buffer;
+ u8 *dma_buffer = PTR_ALIGN(&priv->buffer[0], 16);
dev_dbg(&priv->pci_dev->dev, "Processing completed descriptor\n");
__ismt_desc_dump(&priv->pci_dev->dev, desc);
@@ -395,11 +395,12 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
struct ismt_desc *desc;
struct ismt_priv *priv = i2c_get_adapdata(adap);
struct device *dev = &priv->pci_dev->dev;
+ u8 *dma_buffer = PTR_ALIGN(&priv->buffer[0], 16);
desc = &priv->hw[priv->head];
/* Initialize the DMA buffer */
- memset(priv->dma_buffer, 0, sizeof(priv->dma_buffer));
+ memset(priv->buffer, 0, sizeof(priv->buffer));
/* Initialize the descriptor */
memset(desc, 0, sizeof(struct ismt_desc));
@@ -448,8 +449,8 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
desc->wr_len_cmd = 2;
dma_size = 2;
dma_direction = DMA_TO_DEVICE;
- priv->dma_buffer[0] = command;
- priv->dma_buffer[1] = data->byte;
+ dma_buffer[0] = command;
+ dma_buffer[1] = data->byte;
} else {
/* Read Byte */
dev_dbg(dev, "I2C_SMBUS_BYTE_DATA: READ\n");
@@ -468,9 +469,9 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
desc->wr_len_cmd = 3;
dma_size = 3;
dma_direction = DMA_TO_DEVICE;
- priv->dma_buffer[0] = command;
- priv->dma_buffer[1] = data->word & 0xff;
- priv->dma_buffer[2] = data->word >> 8;
+ dma_buffer[0] = command;
+ dma_buffer[1] = data->word & 0xff;
+ dma_buffer[2] = data->word >> 8;
} else {
/* Read Word */
dev_dbg(dev, "I2C_SMBUS_WORD_DATA: READ\n");
@@ -488,9 +489,9 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
desc->rd_len = 2;
dma_size = 3;
dma_direction = DMA_BIDIRECTIONAL;
- priv->dma_buffer[0] = command;
- priv->dma_buffer[1] = data->word & 0xff;
- priv->dma_buffer[2] = data->word >> 8;
+ dma_buffer[0] = command;
+ dma_buffer[1] = data->word & 0xff;
+ dma_buffer[2] = data->word >> 8;
break;
case I2C_SMBUS_BLOCK_DATA:
@@ -501,8 +502,8 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
dma_direction = DMA_TO_DEVICE;
desc->wr_len_cmd = dma_size;
desc->control |= ISMT_DESC_BLK;
- priv->dma_buffer[0] = command;
- memcpy(&priv->dma_buffer[1], &data->block[1], dma_size - 1);
+ dma_buffer[0] = command;
+ memcpy(&dma_buffer[1], &data->block[1], dma_size - 1);
} else {
/* Block Read */
dev_dbg(dev, "I2C_SMBUS_BLOCK_DATA: READ\n");
@@ -529,8 +530,8 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
dma_direction = DMA_TO_DEVICE;
desc->wr_len_cmd = dma_size;
desc->control |= ISMT_DESC_I2C;
- priv->dma_buffer[0] = command;
- memcpy(&priv->dma_buffer[1], &data->block[1], dma_size - 1);
+ dma_buffer[0] = command;
+ memcpy(&dma_buffer[1], &data->block[1], dma_size - 1);
} else {
/* i2c Block Read */
dev_dbg(dev, "I2C_SMBUS_I2C_BLOCK_DATA: READ\n");
@@ -559,18 +560,18 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
if (dma_size != 0) {
dev_dbg(dev, " dev=%p\n", dev);
dev_dbg(dev, " data=%p\n", data);
- dev_dbg(dev, " dma_buffer=%p\n", priv->dma_buffer);
+ dev_dbg(dev, " dma_buffer=%p\n", dma_buffer);
dev_dbg(dev, " dma_size=%d\n", dma_size);
dev_dbg(dev, " dma_direction=%d\n", dma_direction);
dma_addr = dma_map_single(dev,
- priv->dma_buffer,
+ dma_buffer,
dma_size,
dma_direction);
if (dma_mapping_error(dev, dma_addr)) {
dev_err(dev, "Error in mapping dma buffer %p\n",
- priv->dma_buffer);
+ dma_buffer);
return -EIO;
}

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