Workaround for some broken BIOSes that forgot to enable ATA channels [patch]

[Maxim Sobolev]

Hi,

Attached please find a patch, which workaround a bug found in
some BIOSes, which forget to enable ATA channels properly.
This results in ATA driver not attaching properly and inability
to use disk devices.

Thanks!

-Maxim
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Index: conf/NOTES
===================================================================
RCS file: /home/ncvs/src/sys/conf/NOTES,v
retrieving revision 1.1140
diff -d -u -r1.1140 NOTES
--- conf/NOTES	22 Mar 2003 14:18:21 -0000	1.1140
+++ conf/NOTES	14 Apr 2003 09:59:48 -0000
@@ -1370,8 +1370,11 @@
 #
 # ATA_STATIC_ID:	controller numbering is static ie depends on location
 #			else the device numbers are dynamically allocated.
+# ATA_ENABLE_CHANNELS:	forcefully enable channels if they appear disabled
+#			by BIOS. Some buggy BIOSes "forget" to enable them.
 
 options 	ATA_STATIC_ID
+#options	ATA_ENABLE_CHANNELS
 
 #
 # Standard floppy disk controllers and floppy tapes, supports
Index: conf/options
===================================================================
RCS file: /home/ncvs/src/sys/conf/options,v
retrieving revision 1.383
diff -d -u -r1.383 options
--- conf/options	25 Mar 2003 05:45:04 -0000	1.383
+++ conf/options	14 Apr 2003 09:59:49 -0000
@@ -299,6 +300,7 @@
 
 # Options used in the 'ata' ATA/ATAPI driver
 ATA_STATIC_ID		opt_ata.h
+ATA_ENABLE_CHANNELS	opt_ata.h
 ATA_NOPCI		opt_ata.h
 DEV_ATADISK		opt_ata.h
 DEV_ATAPICD		opt_ata.h
Index: dev/ata/ata-pci.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/ata/ata-pci.c,v
retrieving revision 1.57
diff -d -u -r1.57 ata-pci.c
--- dev/ata/ata-pci.c	25 Feb 2003 14:46:30 -0000	1.57
+++ dev/ata/ata-pci.c	14 Apr 2003 09:59:49 -0000
@@ -129,6 +129,13 @@
     subclass = pci_get_subclass(dev);
     cmd = pci_read_config(dev, PCIR_COMMAND, 2);
 
+#ifdef ATA_ENABLE_CHANNELS
+    if (!(cmd & PCIM_CMD_PORTEN)) {
+	pci_write_config(dev, PCIR_COMMAND, cmd | PCIM_CMD_PORTEN, 2);
+	cmd = pci_read_config(dev, PCIR_COMMAND, 2);
+    }
+#endif
+
     if (!(cmd & PCIM_CMD_PORTEN)) {
 	device_printf(dev, "ATA channel disabled by BIOS\n");
 	return 0;