[PATCH v2] mmc: mmci: Allow MMCI to request channels with information acquired from DT

[Lee Jones <lee.jones@linaro.org>]

Currently, if DMA information isn't passed from platform data, then DMA
will not be used. This patch allows DMA information obtained though Device
Tree to be used as well.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Chris Ball <cjb@laptop.org>
Cc: linux-mmc@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 372e921..45dda46 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -304,10 +304,8 @@ static void mmci_dma_setup(struct mmci_host *host)
 	const char *rxname, *txname;
 	dma_cap_mask_t mask;
 
-	if (!plat || !plat->dma_filter) {
-		dev_info(mmc_dev(host->mmc), "no DMA platform data\n");
-		return;
-	}
+	host->dma_rx_channel = dma_request_slave_channel(mmc_dev(host->mmc), "rx");
+	host->dma_tx_channel = dma_request_slave_channel(mmc_dev(host->mmc), "tx");
 
 	/* initialize pre request cookie */
 	host->next_data.cookie = 1;
@@ -316,30 +314,33 @@ static void mmci_dma_setup(struct mmci_host *host)
 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);
 
-	/*
-	 * If only an RX channel is specified, the driver will
-	 * attempt to use it bidirectionally, however if it is
-	 * is specified but cannot be located, DMA will be disabled.
-	 */
-	if (plat->dma_rx_param) {
-		host->dma_rx_channel = dma_request_channel(mask,
+	if (plat && plat->dma_filter) {
+		if (!host->dma_rx_channel && plat->dma_rx_param) {
+			host->dma_rx_channel = dma_request_channel(mask,
 							   plat->dma_filter,
 							   plat->dma_rx_param);
-		/* E.g if no DMA hardware is present */
-		if (!host->dma_rx_channel)
-			dev_err(mmc_dev(host->mmc), "no RX DMA channel\n");
-	}
+			/* E.g if no DMA hardware is present */
+			if (!host->dma_rx_channel)
+				dev_err(mmc_dev(host->mmc), "no RX DMA channel\n");
+		}
 
-	if (plat->dma_tx_param) {
-		host->dma_tx_channel = dma_request_channel(mask,
+		if (!host->dma_tx_channel && plat->dma_tx_param) {
+			host->dma_tx_channel = dma_request_channel(mask,
 							   plat->dma_filter,
 							   plat->dma_tx_param);
-		if (!host->dma_tx_channel)
-			dev_warn(mmc_dev(host->mmc), "no TX DMA channel\n");
-	} else {
-		host->dma_tx_channel = host->dma_rx_channel;
+			if (!host->dma_tx_channel)
+				dev_warn(mmc_dev(host->mmc), "no TX DMA channel\n");
+		}
 	}
 
+	/*
+	 * If only an RX channel is specified, the driver will
+	 * attempt to use it bidirectionally, however if it is
+	 * is specified but cannot be located, DMA will be disabled.
+	 */
+	if (host->dma_rx_channel && !host->dma_tx_channel)
+		host->dma_tx_channel = host->dma_rx_channel;
+
 	if (host->dma_rx_channel)
 		rxname = dma_chan_name(host->dma_rx_channel);
 	else