[PATCH 13/20] Blackfin SPI Driver: add timeout while waiting for SPIF in dma irq handler

[Bryan Wu <cooloney-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

From: Mike Frysinger <vapier.adi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Bryan Wu <cooloney-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 drivers/spi/spi_bfin5xx.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 83398b3..748e98f 100644
--- 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;
-- 
1.5.6.3

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