Since the MMC/SD controller in Ingenic SoCs work in half-duplex, it is
possible to use one single DMA channel for both TX and RX operations,
instead of using separate channels.
As some older Ingenic SoCs offer only a handful of DMA channels,
supporting bi-directional channels allow more hardware to use the
channels that would otherwise be used for the MMC/SD operation.
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
drivers/mmc/host/jz4740_mmc.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
index 80a2c270d502..a0b94f61ddcf 100644
--- a/drivers/mmc/host/jz4740_mmc.c
+++ b/drivers/mmc/host/jz4740_mmc.c
@@ -217,11 +217,23 @@ static void jz4740_mmc_release_dma_channels(struct jz4740_mmc_host *host)
return;
dma_release_channel(host->dma_tx);
- dma_release_channel(host->dma_rx);
+ if (host->dma_rx)
+ dma_release_channel(host->dma_rx);
}
static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
{
+ struct device *dev = mmc_dev(host->mmc);
+
+ host->dma_tx = dma_request_chan(dev, "tx-rx");
+ if (!IS_ERR(host->dma_tx))
+ return 0;
+
+ if (PTR_ERR(host->dma_tx) != -ENODEV) {
+ dev_err(dev, "Failed to get dma tx-rx channel\n");
+ return PTR_ERR(host->dma_tx);
+ }
+
host->dma_tx = dma_request_chan(mmc_dev(host->mmc), "tx");
if (IS_ERR(host->dma_tx)) {
dev_err(mmc_dev(host->mmc), "Failed to get dma_tx channel\n");
@@ -241,7 +253,10 @@ static int jz4740_mmc_acquire_dma_channels(struct jz4740_mmc_host *host)
static inline struct dma_chan *jz4740_mmc_get_dma_chan(struct jz4740_mmc_host *host,
struct mmc_data *data)
{
- return (data->flags & MMC_DATA_READ) ? host->dma_rx : host->dma_tx;
+ if ((data->flags & MMC_DATA_READ) && host->dma_rx)
+ return host->dma_rx;
+ else
+ return host->dma_tx;
}
static void jz4740_mmc_dma_unmap(struct jz4740_mmc_host *host,
--
2.34.1
