add a timeout to saa7146_i2c_writeout() to prevent endless loop

1 files changed, 16 insertions, 2 deletions

diff --git a/linux/drivers/media/common/saa7146_i2c.c b/linux/drivers/media/common/saa7146_i2c.c
index adbf61aa6..b73803310 100644
--- a/linux/drivers/media/common/saa7146_i2c.c
+++ b/linux/drivers/media/common/saa7146_i2c.c
@@ -193,6 +193,7 @@ static
 int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword)
 {
 	u32 status = 0, mc2 = 0;
+	int timeout;
 
 	/* write out i2c-command */
 	DEB_I2C(("before: 0x%08x (status: 0x%08x), %d\n",*dword,saa7146_read(dev, I2C_STATUS), dev->i2c_op));
@@ -205,11 +206,11 @@ int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword)
 		dev->i2c_op = 1;
 		IER_ENABLE(dev, MASK_16|MASK_17);
 		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
-	
+
 		wait_event_interruptible(dev->i2c_wq, dev->i2c_op == 0);
 		if (signal_pending (current)) {
 			/* a signal arrived */
-			return -ERESTARTSYS; 
+			return -ERESTARTSYS;
 		}
 		status = saa7146_read(dev, I2C_STATUS);
 	} else {
@@ -218,18 +219,31 @@ int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword)
 		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
 
 		/* do not poll for i2c-status before upload is complete */
+		timeout = jiffies + HZ/100 + 1; /* 10ms */
 		while(1) {
 			mc2 = (saa7146_read(dev, MC2) & 0x1);
 			if( 0 != mc2 ) {
 				break;
 			}
+			if (jiffies > timeout) {
+				printk(KERN_WARNING "saa7146_i2c_writeout: timed out waiting for MC2\n");
+				return -EIO;
+			}
 		}
 		/* wait until we get a transfer done or error */
+		timeout = jiffies + HZ/100 + 1; /* 10ms */
 		while(1) {
 			status = saa7146_i2c_status(dev);
 			if( (0x3 == (status & 0x3)) || (0 == (status & 0x1)) ) {
 				break;
 			}
+			if (jiffies > timeout) {
+				/* this is normal when probing the bus
+				 * (no answer from nonexisistant device...)
+				 */
+				DEB_I2C(("saa7146_i2c_writeout: timed out waiting for end of xfer\n"));
+				return -EIO;
+			}
 			my_wait(dev,1);
 		}
 	}