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

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Date:	Wed, 24 Apr 2013 16:55:47 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	arnd@...db.de, linus.walleij@...ricsson.com,
	Russell King <linux@....linux.org.uk>,
	Chris Ball <cjb@...top.org>, linux-mmc@...r.kernel.org
Subject: [PATCH v2] mmc: mmci: Allow MMCI to request channels with
 information acquired from DT

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@....linux.org.uk>
Cc: Chris Ball <cjb@...top.org>
Cc: linux-mmc@...r.kernel.org
Signed-off-by: Lee Jones <lee.jones@...aro.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
--
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