1 files changed, 22 insertions, 10 deletions

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 61eef47ae821..b3db4612b622 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -809,6 +809,10 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
         return 0;
 }
 
+/*
+ * Note that we currently allow DMA only if we get a channel
+ * for both rx and tx. Otherwise we'll do PIO for both rx and tx.
+ */
 static int omap2_mcspi_request_dma(struct spi_device *spi)
 {
         struct spi_master       *master = spi->master;
@@ -827,21 +831,22 @@ static int omap2_mcspi_request_dma(struct spi_device *spi)
         dma_cap_set(DMA_SLAVE, mask);
         sig = mcspi_dma->dma_rx_sync_dev;
         mcspi_dma->dma_rx = dma_request_channel(mask, omap_dma_filter_fn, &sig);
-        if (!mcspi_dma->dma_rx) {
-                dev_err(&spi->dev, "no RX DMA engine channel for McSPI\n");
-                return -EAGAIN;
-        }
+        if (!mcspi_dma->dma_rx)
+                goto no_dma;
 
         sig = mcspi_dma->dma_tx_sync_dev;
         mcspi_dma->dma_tx = dma_request_channel(mask, omap_dma_filter_fn, &sig);
         if (!mcspi_dma->dma_tx) {
-                dev_err(&spi->dev, "no TX DMA engine channel for McSPI\n");
                 dma_release_channel(mcspi_dma->dma_rx);
                 mcspi_dma->dma_rx = NULL;
-                return -EAGAIN;
+                goto no_dma;
         }
 
         return 0;
+
+no_dma:
+        dev_warn(&spi->dev, "not using DMA for McSPI\n");
+        return -EAGAIN;
 }
 
 static int omap2_mcspi_setup(struct spi_device *spi)
@@ -874,7 +879,7 @@ static int omap2_mcspi_setup(struct spi_device *spi)
 
         if (!mcspi_dma->dma_rx || !mcspi_dma->dma_tx) {
                 ret = omap2_mcspi_request_dma(spi);
-                if (ret < 0)
+                if (ret < 0 && ret != -EAGAIN)
                         return ret;
         }
 
@@ -932,6 +937,7 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
         struct spi_device               *spi;
         struct spi_transfer             *t = NULL;
         struct spi_master               *master;
+        struct omap2_mcspi_dma          *mcspi_dma;
         int                             cs_active = 0;
         struct omap2_mcspi_cs           *cs;
         struct omap2_mcspi_device_config *cd;
@@ -941,6 +947,7 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 
         spi = m->spi;
         master = spi->master;
+        mcspi_dma = mcspi->dma_channels + spi->chip_select;
         cs = spi->controller_state;
         cd = spi->controller_data;
 
@@ -997,7 +1004,8 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
                                 __raw_writel(0, cs->base
                                                 + OMAP2_MCSPI_TX0);
 
-                        if (m->is_dma_mapped || t->len >= DMA_MIN_BYTES)
+                        if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
+                            (m->is_dma_mapped || t->len >= DMA_MIN_BYTES))
                                 count = omap2_mcspi_txrx_dma(spi, t);
                         else
                                 count = omap2_mcspi_txrx_pio(spi, t);
@@ -1044,10 +1052,14 @@ static void omap2_mcspi_work(struct omap2_mcspi *mcspi, struct spi_message *m)
 static int omap2_mcspi_transfer_one_message(struct spi_master *master,
                 struct spi_message *m)
 {
+        struct spi_device       *spi;
         struct omap2_mcspi      *mcspi;
+        struct omap2_mcspi_dma  *mcspi_dma;
         struct spi_transfer     *t;
 
+        spi = m->spi;
         mcspi = spi_master_get_devdata(master);
+        mcspi_dma = mcspi->dma_channels + spi->chip_select;
         m->actual_length = 0;
         m->status = 0;
 
@@ -1082,7 +1094,7 @@ static int omap2_mcspi_transfer_one_message(struct spi_master *master,
                 if (m->is_dma_mapped || len < DMA_MIN_BYTES)
                         continue;
 
-                if (tx_buf != NULL) {
+                if (mcspi_dma->dma_tx && tx_buf != NULL) {
                         t->tx_dma = dma_map_single(mcspi->dev, (void *) tx_buf,
                                         len, DMA_TO_DEVICE);
                         if (dma_mapping_error(mcspi->dev, t->tx_dma)) {
@@ -1091,7 +1103,7 @@ static int omap2_mcspi_transfer_one_message(struct spi_master *master,
                                 return -EINVAL;
                         }
                 }
-                if (rx_buf != NULL) {
+                if (mcspi_dma->dma_rx && rx_buf != NULL) {
                         t->rx_dma = dma_map_single(mcspi->dev, rx_buf, t->len,
                                         DMA_FROM_DEVICE);
                         if (dma_mapping_error(mcspi->dev, t->rx_dma)) {