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@xxxxxxxxx>
---
drivers/i2c/busses/i2c-ismt.c | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)
diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index b51adffa4841..f4f806135119 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);
@@ -393,11 +393,12 @@ 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));
@@ -446,8 +447,8 @@ 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");
@@ -466,9 +467,9 @@ 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");
@@ -486,9 +487,9 @@ 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:
@@ -499,8 +500,8 @@ 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");
@@ -527,8 +528,8 @@ 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");
@@ -557,18 +558,18 @@ 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;
}
--
2.13.6
