Blackfin SPI Driver: add timeout while waiting for SPIF in dma irq handler

The "while" endless loop will cause the system hang if hardware error, so
we add timeout control to make the system alive.

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 88dee87fc420fa81dc310d3ad18e68a46ef31ca8..e706de1d10c840ee6d8730cd12eec15c3ee1704f 100644 (file)
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -557,6 +557,7 @@ static irqreturn_t dma_irq_handler(int irq, void *dev_id)
        struct driver_data *drv_data = dev_id;
        struct chip_data *chip = drv_data->cur_chip;
        struct spi_message *msg = drv_data->cur_msg;
+       unsigned long timeout;
        unsigned short dmastat = get_dma_curr_irqstat(drv_data->dma_channel);
        u16 spistat = read_STAT(drv_data);
 
@@ -582,8 +583,17 @@ static irqreturn_t dma_irq_handler(int irq, void *dev_id)
                        cpu_relax();
        }
 
+       dev_dbg(&drv_data->pdev->dev,
+               "in dma_irq_handler dmastat:0x%x spistat:0x%x\n",
+               dmastat, read_STAT(drv_data));
+
+       timeout = jiffies + HZ;
        while (!(read_STAT(drv_data) & SPIF))
-               cpu_relax();
+               if (!time_before(jiffies, timeout)) {
+                       dev_warn(&drv_data->pdev->dev, "timeout waiting for SPIF");
+                       break;
+               } else
+                       cpu_relax();
 
        if ((dmastat & DMA_ERR) && (spistat & RBSY)) {
                msg->state = ERROR_STATE;