- optimize the i2c retry-address error problem by distinguishing between

  analog tv cards and dvb cards. (see source comments for further
  informations)

1 files changed, 26 insertions, 9 deletions

diff --git a/linux/drivers/media/common/saa7146_i2c.c b/linux/drivers/media/common/saa7146_i2c.c
index 9a0092635..cade026d2 100644
--- a/linux/drivers/media/common/saa7146_i2c.c
+++ b/linux/drivers/media/common/saa7146_i2c.c
@@ -313,7 +313,23 @@ int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg msgs[], i
 		for(i = 0; i < count; i++) {
 			err = saa7146_i2c_writeout(dev, &buffer[i] );
 			if ( 0 != err) {
+				/* this one is unsatisfying: some i2c slaves on some
+				   dvb cards don't acknowledge correctly, so the saa7146
+				   thinks that an address error occured. in that case, the
+				   transaction should be retrying, even if an address error
+				   occured. analog saa7146 based cards extensively rely on
+				   i2c address probing, however, and address errors indicate that a 
+				   device is really *not* there. retrying in that case
+				   increases the time the device needs to probe greatly, so
+				   it should be avoided. because of the fact, that only 
+				   analog based cards use irq based i2c transactions (for dvb
+				   cards, this screwes up other interrupt sources), we bail out
+				   completely for analog cards after an address error and trust
+				   the saa7146 address error detection. */
 				if ( -EREMOTEIO == err ) {
+					if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {
+						goto out;
+					}
 				        address_err++;
 				}
 				DEB_I2C(("error while sending message(s). starting again.\n"));
@@ -330,15 +346,6 @@ int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg msgs[], i
 		
 	} while (err != num && retries--);
 
-	/* another bug in revision 0: the i2c-registers get uploaded randomly by other
-	   uploads, so we better clear them out before continueing */	
-	if( 0 == dev->revision ) {
-		u32 zero = 0;
-		if( 0 != saa7146_i2c_writeout(dev, &zero)) {
-			INFO(("revision 0 error. this should never happen.\n"));
-		}
-	}
-   
         /* if every retry had an address error, exit right away */
         if (address_err == retries) {
 	        goto out;
@@ -354,6 +361,16 @@ int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg msgs[], i
 	/* return the number of delivered messages */
 	DEB_I2C(("transmission successful. (msg:%d).\n",err));
 out:
+	/* another bug in revision 0: the i2c-registers get uploaded randomly by other
+	   uploads, so we better clear them out before continueing */	
+	if( 0 == dev->revision ) {
+		u32 zero = 0;
+		saa7146_i2c_reset(dev);
+		if( 0 != saa7146_i2c_writeout(dev, &zero)) {
+			INFO(("revision 0 error. this should never happen.\n"));
+		}
+	}
+
 	up(&dev->i2c_lock);
 	return err;	
 }