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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>
This commit is contained in:
Radu Rendec 2018-01-04 18:18:13 +00:00 committed by Wolfram Sang
parent 38a99bd773
commit 5cd5f0bb0d
1 changed files with 19 additions and 18 deletions
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37
drivers/i2c/busses/i2c-ismt.c
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@ -172,7 +172,7 @@ struct ismt_priv {
dma_addr_t io_rng_dma; /* descriptor HW base addr */ dma_addr_t io_rng_dma; /* descriptor HW base addr */
u8 head; /* ring buffer head pointer */ u8 head; /* ring buffer head pointer */
struct completion cmp; /* interrupt completion */ 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, struct ismt_priv *priv, int size,
char read_write) 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"); dev_dbg(&priv->pci_dev->dev, "Processing completed descriptor\n");
__ismt_desc_dump(&priv->pci_dev->dev, desc); __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_desc *desc;
struct ismt_priv *priv = i2c_get_adapdata(adap); struct ismt_priv *priv = i2c_get_adapdata(adap);
struct device *dev = &priv->pci_dev->dev; struct device *dev = &priv->pci_dev->dev;
u8 *dma_buffer = PTR_ALIGN(&priv->buffer[0], 16);
desc = &priv->hw[priv->head]; desc = &priv->hw[priv->head];
/* Initialize the DMA buffer */ /* Initialize the DMA buffer */
memset(priv->dma_buffer, 0, sizeof(priv->dma_buffer)); memset(priv->buffer, 0, sizeof(priv->buffer));
/* Initialize the descriptor */ /* Initialize the descriptor */
memset(desc, 0, sizeof(struct ismt_desc)); 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; desc->wr_len_cmd = 2;
dma_size = 2; dma_size = 2;
dma_direction = DMA_TO_DEVICE; dma_direction = DMA_TO_DEVICE;
priv->dma_buffer[0] = command; dma_buffer[0] = command;
priv->dma_buffer[1] = data->byte; dma_buffer[1] = data->byte;
} else { } else {
/* Read Byte */ /* Read Byte */
dev_dbg(dev, "I2C_SMBUS_BYTE_DATA: READ\n"); 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; desc->wr_len_cmd = 3;
dma_size = 3; dma_size = 3;
dma_direction = DMA_TO_DEVICE; dma_direction = DMA_TO_DEVICE;
priv->dma_buffer[0] = command; dma_buffer[0] = command;
priv->dma_buffer[1] = data->word & 0xff; dma_buffer[1] = data->word & 0xff;
priv->dma_buffer[2] = data->word >> 8; dma_buffer[2] = data->word >> 8;
} else { } else {
/* Read Word */ /* Read Word */
dev_dbg(dev, "I2C_SMBUS_WORD_DATA: READ\n"); 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; desc->rd_len = 2;
dma_size = 3; dma_size = 3;
dma_direction = DMA_BIDIRECTIONAL; dma_direction = DMA_BIDIRECTIONAL;
priv->dma_buffer[0] = command; dma_buffer[0] = command;
priv->dma_buffer[1] = data->word & 0xff; dma_buffer[1] = data->word & 0xff;
priv->dma_buffer[2] = data->word >> 8; dma_buffer[2] = data->word >> 8;
break; break;
case I2C_SMBUS_BLOCK_DATA: case I2C_SMBUS_BLOCK_DATA:
@ -501,8 +502,8 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
dma_direction = DMA_TO_DEVICE; dma_direction = DMA_TO_DEVICE;
desc->wr_len_cmd = dma_size; desc->wr_len_cmd = dma_size;
desc->control |= ISMT_DESC_BLK; desc->control |= ISMT_DESC_BLK;
priv->dma_buffer[0] = command; dma_buffer[0] = command;
memcpy(&priv->dma_buffer[1], &data->block[1], dma_size - 1); memcpy(&dma_buffer[1], &data->block[1], dma_size - 1);
} else { } else {
/* Block Read */ /* Block Read */
dev_dbg(dev, "I2C_SMBUS_BLOCK_DATA: READ\n"); 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; dma_direction = DMA_TO_DEVICE;
desc->wr_len_cmd = dma_size; desc->wr_len_cmd = dma_size;
desc->control |= ISMT_DESC_I2C; desc->control |= ISMT_DESC_I2C;
priv->dma_buffer[0] = command; dma_buffer[0] = command;
memcpy(&priv->dma_buffer[1], &data->block[1], dma_size - 1); memcpy(&dma_buffer[1], &data->block[1], dma_size - 1);
} else { } else {
/* i2c Block Read */ /* i2c Block Read */
dev_dbg(dev, "I2C_SMBUS_I2C_BLOCK_DATA: READ\n"); 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) { if (dma_size != 0) {
dev_dbg(dev, " dev=%p\n", dev); dev_dbg(dev, " dev=%p\n", dev);
dev_dbg(dev, " data=%p\n", data); 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_size=%d\n", dma_size);
dev_dbg(dev, " dma_direction=%d\n", dma_direction); dev_dbg(dev, " dma_direction=%d\n", dma_direction);
dma_addr = dma_map_single(dev, dma_addr = dma_map_single(dev,
priv->dma_buffer, dma_buffer,
dma_size, dma_size,
dma_direction); dma_direction);
if (dma_mapping_error(dev, dma_addr)) { if (dma_mapping_error(dev, dma_addr)) {
dev_err(dev, "Error in mapping dma buffer %p\n", dev_err(dev, "Error in mapping dma buffer %p\n",
priv->dma_buffer); dma_buffer);
return -EIO; return -EIO;
} }