spi_bfin5xx: use PIO for full duplex, not DMA
Vitja Makarov [Thu, 1 May 2008 11:35:03 +0000 (04:35 -0700)]
Use PIO for full-duplex transfers, instead of DMA.

Signed-off-by: Vitja Makarov <vitja.makarov@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bfin5xx.c

index a9ac1fd..7fea3cf 100644 (file)
@@ -608,6 +608,7 @@ static void pump_transfers(unsigned long data)
        u8 width;
        u16 cr, dma_width, dma_config;
        u32 tranf_success = 1;
+       u8 full_duplex = 0;
 
        /* Get current state information */
        message = drv_data->cur_msg;
@@ -658,6 +659,7 @@ static void pump_transfers(unsigned long data)
        }
 
        if (transfer->rx_buf != NULL) {
+               full_duplex = transfer->tx_buf != NULL;
                drv_data->rx = transfer->rx_buf;
                drv_data->rx_end = drv_data->rx + transfer->len;
                dev_dbg(&drv_data->pdev->dev, "rx_buf is %p, rx_end is %p\n",
@@ -740,7 +742,8 @@ static void pump_transfers(unsigned long data)
         * successful use different way to r/w according to
         * drv_data->cur_chip->enable_dma
         */
-       if (drv_data->cur_chip->enable_dma && drv_data->len > 6) {
+       if (!full_duplex && drv_data->cur_chip->enable_dma
+                               && drv_data->len > 6) {
 
                disable_dma(drv_data->dma_channel);
                clear_dma_irqstat(drv_data->dma_channel);
@@ -828,7 +831,7 @@ static void pump_transfers(unsigned long data)
                /* IO mode write then read */
                dev_dbg(&drv_data->pdev->dev, "doing IO transfer\n");
 
-               if (drv_data->tx != NULL && drv_data->rx != NULL) {
+               if (full_duplex) {
                        /* full duplex mode */
                        BUG_ON((drv_data->tx_end - drv_data->tx) !=
                               (drv_data->rx_end - drv_data->rx));