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| author |   Paul Cercueil <paul@crapouillou.net> | 2021-12-20 19:08:40 +0000 |
|---|---|---|
| committer |   Ulf Hansson <ulf.hansson@linaro.org> | 2021-12-21 13:38:38 +0100 |
| commit | a474e52c3109870946755925ce379d730a6dcaf7 (patch) | |
| tree | 1047433931431f004bfc3c68c37da34002dc2c8a /drivers/mmc | |
| parent | dt-bindings: mmc: ingenic: Support using bi-directional DMA channel (diff) | |
| download | linux-dev-a474e52c3109870946755925ce379d730a6dcaf7.tar.xz linux-dev-a474e52c3109870946755925ce379d730a6dcaf7.zip | |
mmc: jz4740: Support using a bi-directional DMA channel
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@crapouillou.net>
Link: https://lore.kernel.org/r/20211220190840.108061-3-paul@crapouillou.net
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/jz4740_mmc.c | 19 |
1 files 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, |