spi: davinci: handle DMA completion errors correctly

Do not simply clean the DMA channel on a DMA completion
error. Instead, use wcount and rcount members of davinci_spi
to detecion non-completion of DMA and signal EIO to the
application.

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Tested-By: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

1 files changed, 36 insertions, 27 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index 975c2a228d0a..a47947da17a3 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -388,24 +388,26 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
 
 static void davinci_spi_dma_rx_callback(unsigned lch, u16 ch_status, void *data)
 {
-        struct davinci_spi_dma *davinci_spi_dma = data;
+        struct davinci_spi *davinci_spi = data;
+        struct davinci_spi_dma *davinci_spi_dma = &davinci_spi->dma_channels;
+
+        edma_stop(davinci_spi_dma->dma_rx_channel);
 
         if (ch_status == DMA_COMPLETE)
-                edma_stop(davinci_spi_dma->dma_rx_channel);
-        else
-                edma_clean_channel(davinci_spi_dma->dma_rx_channel);
+                davinci_spi->rcount = 0;
 
         complete(&davinci_spi_dma->dma_rx_completion);
 }
 
 static void davinci_spi_dma_tx_callback(unsigned lch, u16 ch_status, void *data)
 {
-        struct davinci_spi_dma *davinci_spi_dma = data;
+        struct davinci_spi *davinci_spi = data;
+        struct davinci_spi_dma *davinci_spi_dma = &davinci_spi->dma_channels;
+
+        edma_stop(davinci_spi_dma->dma_tx_channel);
 
         if (ch_status == DMA_COMPLETE)
-                edma_stop(davinci_spi_dma->dma_tx_channel);
-        else
-                edma_clean_channel(davinci_spi_dma->dma_tx_channel);
+                davinci_spi->wcount = 0;
 
         complete(&davinci_spi_dma->dma_tx_completion);
 }
@@ -632,7 +634,6 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
 {
         struct davinci_spi *davinci_spi;
         int int_status = 0;
-        int count;
         unsigned rx_buf_count;
         struct davinci_spi_dma *davinci_spi_dma;
         int data_type, ret;
@@ -648,20 +649,20 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
 
         davinci_spi_dma = &davinci_spi->dma_channels;
 
+        /* convert len to words based on bits_per_word */
+        data_type = davinci_spi->bytes_per_word[spi->chip_select];
+
         tx_reg = (unsigned long)davinci_spi->pbase + SPIDAT1;
         rx_reg = (unsigned long)davinci_spi->pbase + SPIBUF;
 
         davinci_spi->tx = t->tx_buf;
         davinci_spi->rx = t->rx_buf;
-
-        /* convert len to words based on bits_per_word */
-        data_type = davinci_spi->bytes_per_word[spi->chip_select];
+        davinci_spi->wcount = t->len / data_type;
+        davinci_spi->rcount = davinci_spi->wcount;
 
         init_completion(&davinci_spi_dma->dma_rx_completion);
         init_completion(&davinci_spi_dma->dma_tx_completion);
 
-        count = t->len / data_type;     /* the number of elements */
-
         /* disable all interrupts for dma transfers */
         clear_io_bits(davinci_spi->base + SPIINT, SPIINT_MASKALL);
         /* Enable SPI */
@@ -680,18 +681,18 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
          */
 
         if (t->tx_buf) {
-                t->tx_dma = dma_map_single(&spi->dev, (void *)t->tx_buf, count,
-                                DMA_TO_DEVICE);
+                t->tx_dma = dma_map_single(&spi->dev, (void *)t->tx_buf,
+                                        davinci_spi->wcount, DMA_TO_DEVICE);
                 if (dma_mapping_error(&spi->dev, t->tx_dma)) {
-                        dev_dbg(sdev, "Unable to DMA map a %d bytes"
-                                " TX buffer\n", count);
+                        dev_dbg(sdev, "Unable to DMA map %d bytes TX buffer\n",
+                                                        davinci_spi->wcount);
                         return -ENOMEM;
                 }
         }
 
         param.opt = TCINTEN | EDMA_TCC(davinci_spi_dma->dma_tx_channel);
         param.src = t->tx_buf ? t->tx_dma : tx_reg;
-        param.a_b_cnt = count << 16 | data_type;
+        param.a_b_cnt = davinci_spi->wcount << 16 | data_type;
         param.dst = tx_reg;
         param.src_dst_bidx = t->tx_buf ? data_type : 0;
         param.link_bcntrld = 0xffff;
@@ -715,7 +716,7 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
 
         if (t->rx_buf) {
                 rx_buf = t->rx_buf;
-                rx_buf_count = count;
+                rx_buf_count = davinci_spi->rcount;
         } else {
                 rx_buf = davinci_spi->rx_tmp_buf;
                 rx_buf_count = sizeof(davinci_spi->rx_tmp_buf);
@@ -727,13 +728,14 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
                 dev_dbg(sdev, "Couldn't DMA map a %d bytes RX buffer\n",
                                                                 rx_buf_count);
                 if (t->tx_buf)
-                        dma_unmap_single(NULL, t->tx_dma, count, DMA_TO_DEVICE);
+                        dma_unmap_single(NULL, t->tx_dma, davinci_spi->wcount,
+                                                                DMA_TO_DEVICE);
                 return -ENOMEM;
         }
 
         param.opt = TCINTEN | EDMA_TCC(davinci_spi_dma->dma_rx_channel);
         param.src = rx_reg;
-        param.a_b_cnt = count << 16 | data_type;
+        param.a_b_cnt = davinci_spi->rcount << 16 | data_type;
         param.dst = t->rx_dma;
         param.src_dst_bidx = (t->rx_buf ? data_type : 0) << 16;
         param.link_bcntrld = 0xffff;
@@ -754,7 +756,8 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
         wait_for_completion_interruptible(&davinci_spi_dma->dma_rx_completion);
 
         if (t->tx_buf)
-                dma_unmap_single(NULL, t->tx_dma, count, DMA_TO_DEVICE);
+                dma_unmap_single(NULL, t->tx_dma, davinci_spi->wcount,
+                                                                DMA_TO_DEVICE);
 
         dma_unmap_single(NULL, t->rx_dma, rx_buf_count, DMA_FROM_DEVICE);
 
@@ -770,15 +773,21 @@ static int davinci_spi_bufs_dma(struct spi_device *spi, struct spi_transfer *t)
         if (ret != 0)
                 return ret;
 
+        if (davinci_spi->rcount != 0 || davinci_spi->wcount != 0) {
+                dev_err(sdev, "SPI data transfer error\n");
+                return -EIO;
+        }
+
         return t->len;
 }
 
-static int davinci_spi_request_dma(struct davinci_spi_dma *davinci_spi_dma)
+static int davinci_spi_request_dma(struct davinci_spi *davinci_spi)
 {
         int r;
+        struct davinci_spi_dma *davinci_spi_dma = &davinci_spi->dma_channels;
 
         r = edma_alloc_channel(davinci_spi_dma->dma_rx_channel,
-                                davinci_spi_dma_rx_callback, davinci_spi_dma,
+                                davinci_spi_dma_rx_callback, davinci_spi,
                                 davinci_spi_dma->eventq);
         if (r < 0) {
                 pr_err("Unable to request DMA channel for SPI RX\n");
@@ -787,7 +796,7 @@ static int davinci_spi_request_dma(struct davinci_spi_dma *davinci_spi_dma)
         }
 
         r = edma_alloc_channel(davinci_spi_dma->dma_tx_channel,
-                                davinci_spi_dma_tx_callback, davinci_spi_dma,
+                                davinci_spi_dma_tx_callback, davinci_spi,
                                 davinci_spi_dma->eventq);
         if (r < 0) {
                 pr_err("Unable to request DMA channel for SPI TX\n");
@@ -929,7 +938,7 @@ static int davinci_spi_probe(struct platform_device *pdev)
                 davinci_spi->dma_channels.dma_tx_channel = dma_tx_chan;
                 davinci_spi->dma_channels.eventq = dma_eventq;
 
-                ret = davinci_spi_request_dma(&davinci_spi->dma_channels);
+                ret = davinci_spi_request_dma(davinci_spi);
                 if (ret)
                         goto free_clk;