patch-2.4.0-prerelease linux/Documentation/parport.txt

• Lines: 47
• Date: Fri Dec 29 14:07:19 2000
• Orig file: v2.4.0-test12/linux/Documentation/parport.txt
• Orig date: Mon Jun 19 17:59:32 2000

diff -u --recursive --new-file v2.4.0-test12/linux/Documentation/parport.txt linux/Documentation/parport.txt
@@ -219,6 +219,46 @@
 
  * IRQ autoprobing works only for a few port types at the moment.
 
+Reporting printer problems with parport
+=======================================
+
+If you are having problems printing, please go through these steps to
+try to narrow down where the problem area is.
+
+When reporting problems with parport, really you need to give all of
+the messages that parport_pc spits out when it initialises.  There are
+several code paths:
+
+o polling
+o interrupt-driven, protocol in software
+o interrupt-driven, protocol in hardware using PIO
+o interrupt-driven, protocol in hardware using DMA
+
+The kernel messages that parport_pc logs give an indication of which
+code path is being used. (They could be a lot better actually..)
+
+For normal printer protocol, having IEEE 1284 modes enabled or not
+should not make a difference.
+
+To turn off the 'protocol in hardware' code paths, disable
+CONFIG_PARPORT_PC_FIFO.  Note that when they are enabled they are not
+necessarily _used_; it depends on whether the hardware is available,
+enabled by the BIOS, and detected by the driver.
+
+So, to start with, disable CONFIG_PARPORT_PC_FIFO, and load parport_pc
+with 'irq=none'. See if printing works then.  It really should,
+because this is the simplest code path.
+
+If that works fine, try with 'io=0x378 irq=7' (adjust for your
+hardware), to make it use interrupt-driven in-software protocol.
+
+If _that_ works fine, then one of the hardware modes isn't working
+right.  Enable CONFIG_PARPORT_PC_FIFO (no, it isn't a module option,
+and yes, it should be), set the port to ECP mode in the BIOS and note
+the DMA channel, and try with:
+
+    io=0x378 irq=7 dma=none (for PIO)
+    io=0x378 irq=7 dma=3 (for DMA)
 --
 Philip.Blundell@pobox.com
 tim@cyberelk.demon.co.uk