diff options
| -rw-r--r-- | drivers/dma/dw-edma/dw-edma-core.c | 49 |
1 files changed, 34 insertions, 15 deletions
diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c index af037ec61a86..23ad07496b10 100644 --- a/drivers/dma/dw-edma/dw-edma-core.c +++ b/drivers/dma/dw-edma/dw-edma-core.c @@ -339,21 +339,40 @@ dw_edma_device_transfer(struct dw_edma_transfer *xfer) if (!chan->configured) return NULL; - switch (chan->config.direction) { - case DMA_DEV_TO_MEM: /* local DMA */ - if (dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_READ) - break; - return NULL; - case DMA_MEM_TO_DEV: /* local DMA */ - if (dir == DMA_MEM_TO_DEV && chan->dir == EDMA_DIR_WRITE) - break; - return NULL; - default: /* remote DMA */ - if (dir == DMA_MEM_TO_DEV && chan->dir == EDMA_DIR_READ) - break; - if (dir == DMA_DEV_TO_MEM && chan->dir == EDMA_DIR_WRITE) - break; - return NULL; + /* + * Local Root Port/End-point Remote End-point + * +-----------------------+ PCIe bus +----------------------+ + * | | +-+ | | + * | DEV_TO_MEM Rx Ch <----+ +---+ Tx Ch DEV_TO_MEM | + * | | | | | | + * | MEM_TO_DEV Tx Ch +----+ +---> Rx Ch MEM_TO_DEV | + * | | +-+ | | + * +-----------------------+ +----------------------+ + * + * 1. Normal logic: + * If eDMA is embedded into the DW PCIe RP/EP and controlled from the + * CPU/Application side, the Rx channel (EDMA_DIR_READ) will be used + * for the device read operations (DEV_TO_MEM) and the Tx channel + * (EDMA_DIR_WRITE) - for the write operations (MEM_TO_DEV). + * + * 2. Inverted logic: + * If eDMA is embedded into a Remote PCIe EP and is controlled by the + * MWr/MRd TLPs sent from the CPU's PCIe host controller, the Tx + * channel (EDMA_DIR_WRITE) will be used for the device read operations + * (DEV_TO_MEM) and the Rx channel (EDMA_DIR_READ) - for the write + * operations (MEM_TO_DEV). + * + * It is the client driver responsibility to choose a proper channel + * for the DMA transfers. + */ + if (chan->dw->chip->flags & DW_EDMA_CHIP_LOCAL) { + if ((chan->dir == EDMA_DIR_READ && dir != DMA_DEV_TO_MEM) || + (chan->dir == EDMA_DIR_WRITE && dir != DMA_MEM_TO_DEV)) + return NULL; + } else { + if ((chan->dir == EDMA_DIR_WRITE && dir != DMA_DEV_TO_MEM) || + (chan->dir == EDMA_DIR_READ && dir != DMA_MEM_TO_DEV)) + return NULL; } if (xfer->type == EDMA_XFER_CYCLIC) { |