Bug#334104: RFC: workaround for dmfe/tulip module problem

[Jurij Smakov <jurij@wooyd.org>]

Hi,

The issue of dmfe and tulip drivers advertising support for the cards 
with the same PCI IDs has popped up recently again [0]. As some of the 
cards work with dmfe driver (mostly on x86), and some work with tulip 
(on sparc Netra machines, for example), the issue cannot be resolved 
by simply removing the duplicate PCI IDs from one of the drivers, as I 
initially thought. To provide some kind of workaround for it, I 
propose to patch dmfe and tulip drivers, introducing a 'disable' 
parameter, which can be used to prevent the particular module from 
taking over hardware. d-i currently has a mechanism to supply the 
options to the modules using kernel boot parameters, so the user may 
disable the unwanted module without starting a shell and manually 
mucking with module loading and unloading.

The patch (attached) is really straightforward, and is unlikely to 
cause any regression. I don't have access to the dmfe or tulip 
hardware, so I would appreciate if you could test it on the 
affected machines (particularly, the disabling feature), and report 
back.

[0] http://bugs.debian.org/400837
 
Thanks,
-- 
Jurij Smakov                                           jurij@wooyd.org
Key: http://www.wooyd.org/pgpkey/                      KeyID: C99E03CC

diff -aur a/drivers/net/tulip/dmfe.c b/drivers/net/tulip/dmfe.c
--- a/drivers/net/tulip/dmfe.c	2006-09-19 20:42:06.000000000 -0700
+++ b/drivers/net/tulip/dmfe.c	2006-11-29 21:00:45.000000000 -0800
@@ -281,6 +281,7 @@
 
 /* For module input parameter */
 static int debug;
+static int disable;
 static u32 cr6set;
 static unsigned char mode = 8;
 static u8 chkmode = 1;
@@ -1987,6 +1988,7 @@
 MODULE_VERSION(DRV_VERSION);
 
 module_param(debug, int, 0);
+module_param(disable, int, 0);
 module_param(mode, byte, 0);
 module_param(cr6set, int, 0);
 module_param(chkmode, byte, 0);
@@ -2008,6 +2010,11 @@
 {
 	int rc;
 
+	if (disable) {
+		printk(KERN_INFO "dmfe: driver disabled, aborting initialization.\n");
+		return 0;
+	}
+
 	printk(version);
 	printed_version = 1;
 
@@ -2055,6 +2062,8 @@
 
 static void __exit dmfe_cleanup_module(void)
 {
+	if (disable)
+		return;
 	DMFE_DBUG(0, "dmfe_clean_module() ", debug);
 	pci_unregister_driver(&dmfe_driver);
 }
diff -aur a/drivers/net/tulip/tulip_core.c b/drivers/net/tulip/tulip_core.c
--- a/drivers/net/tulip/tulip_core.c	2006-09-19 20:42:06.000000000 -0700
+++ b/drivers/net/tulip/tulip_core.c	2006-11-29 21:01:04.000000000 -0800
@@ -106,6 +106,8 @@
 static int csr0 = 0x00A00000 | 0x4800;
 #endif
 
+static int disable;
+
 /* Operational parameters that usually are not changed. */
 /* Time in jiffies before concluding the transmitter is hung. */
 #define TX_TIMEOUT  (4*HZ)
@@ -116,6 +118,7 @@
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);
 module_param(tulip_debug, int, 0);
+module_param(disable, int, 0);
 module_param(max_interrupt_work, int, 0);
 module_param(rx_copybreak, int, 0);
 module_param(csr0, int, 0);
@@ -1840,6 +1843,11 @@
 
 static int __init tulip_init (void)
 {
+	if (disable) {
+		printk (KERN_INFO "tulip: driver disabled, aborting initialization\n");
+		return 0;
+	}
+
 #ifdef MODULE
 	printk (KERN_INFO "%s", version);
 #endif
@@ -1855,6 +1863,8 @@
 
 static void __exit tulip_cleanup (void)
 {
+	if (disable)
+		return;
 	pci_unregister_driver (&tulip_driver);
 }