From 5cd5f0bb0d9c32876b3d86b70fb45da10d028be7 Mon Sep 17 00:00:00 2001 From: Radu Rendec Date: Thu, 4 Jan 2018 18:18:13 +0000 Subject: [PATCH] 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 Acked-by: Neil Horman Signed-off-by: Wolfram Sang --- 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 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; }