[Linux-parport] [PATCH] IEEE1284.3 chain end detection fix

[Marko Kohtala]

This is the same patch I sent earlier. Now against todays BitKeeper and with
the signed-off-by.

My Kodak Advantix FD 300 does not detect itself as last device in chain. This
patch fixes the address assignment stop when it sees status from non
IEEE1284.3 device. Also the logic for last_dev was broken because it assigned
address one past the last device.

It now correctly finds my one broken DC device.

I bundle it together with the second patch to fix opening daisy-chain devices.

Signed-off-by: Marko Kohtala <marko.kohtala at gmail.com>

diff -Nru a/drivers/parport/daisy.c b/drivers/parport/daisy.c
--- a/drivers/parport/daisy.c	2005-03-30 20:36:55 +03:00
+++ b/drivers/parport/daisy.c	2005-03-30 20:36:55 +03:00
@@ -436,7 +436,7 @@

  static int assign_addrs (struct parport *port)
  {
-	unsigned char s, last_dev;
+	unsigned char s;
  	unsigned char daisy;
  	int thisdev = numdevs;
  	int detected;
@@ -472,10 +472,13 @@
  	}

  	parport_write_data (port, 0x78); udelay (2);
-	last_dev = 0; /* We've just been speaking to a device, so we
-			 know there must be at least _one_ out there. */
+	s = parport_read_status (port);

-	for (daisy = 0; daisy < 4; daisy++) {
+	for (daisy = 0;
+	     (s & (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT))
+		     == (PARPORT_STATUS_PAPEROUT|PARPORT_STATUS_SELECT)
+		     && daisy < 4;
+	     ++daisy) {
  		parport_write_data (port, daisy);
  		udelay (2);
  		parport_frob_control (port,
@@ -485,14 +488,18 @@
  		parport_frob_control (port, PARPORT_CONTROL_STROBE, 0);
  		udelay (1);

-		if (last_dev)
-			/* No more devices. */
-			break;
+		add_dev (numdevs++, port, daisy);

-		last_dev = !(parport_read_status (port)
-			     & PARPORT_STATUS_BUSY);
+		/* See if this device thought it was the last in the
+		 * chain. */
+		if (!(s & PARPORT_STATUS_BUSY))
+			break;

-		add_dev (numdevs++, port, daisy);
+		/* We are seeing pass through status now. We see
+		   last_dev from next device or if last_dev does not
+		   work status lines from some non-daisy chain
+		   device. */
+		s = parport_read_status (port);
  	}

  	parport_write_data (port, 0xff); udelay (2);
diff -Nru a/drivers/parport/daisy.c b/drivers/parport/daisy.c
--- a/drivers/parport/daisy.c	2005-01-10 07:58:18 +02:00
+++ b/drivers/parport/daisy.c	2005-01-10 07:58:18 +02:00
@@ -252,7 +252,7 @@
  		selected = port->daisy;
  		parport_release (dev);

-		if (selected != port->daisy) {
+		if (selected != daisy) {
  			/* No corresponding device. */
  			parport_unregister_device (dev);
  			return NULL;