Refine the frame buffer probe again, to correctly detect a newport frame buffer

on Indy if an HPC SCSI board is plugged in either expansion slots, as this
somehow affects pipelined reads of the newport space.

The framebuffer detection is slowly becoming an ISA-like mess...

Thanks to Alain Tauch for giving me an HPC SCSI board (wrapped in yet another
Indy)

1 files changed, 30 insertions, 2 deletions

diff --git a/sys/arch/sgi/gio/gio.c b/sys/arch/sgi/gio/gio.c
index 7f4faf506ae..77341e1d170 100644
--- a/sys/arch/sgi/gio/gio.c
+++ b/sys/arch/sgi/gio/gio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gio.c,v 1.15 2013/04/21 17:13:36 miod Exp $	*/
+/*	$OpenBSD: gio.c,v 1.16 2013/09/28 14:03:13 miod Exp $	*/
 /*	$NetBSD: gio.c,v 1.32 2011/07/01 18:53:46 dyoung Exp $	*/
 
 /*
@@ -371,7 +371,7 @@ gio_id(vaddr_t va, paddr_t pa, int maybe_gfx)
 	}
 
 	/*
-	 * GIO32 devices with a 32-bit ID register will not necesserily
+	 * GIO32 devices with a 32-bit ID register will not necessarily
 	 * answer to addresses not aligned on 32 bit boundaries.
 	 */
 
@@ -403,6 +403,34 @@ gio_id(vaddr_t va, paddr_t pa, int maybe_gfx)
 	 */
 
 	if (maybe_gfx) {
+		/*
+		 * On (at least) Indy systems with newport graphics, the
+		 * presence of a SCSI Expansion board (030-8133) in either
+		 * slot will cause extra bits to be set in the topmost byte
+		 * of the 32-bit access to the pipelined slot (i.e. the
+		 * value of id32 is 0x18000004, not 0x00000004).
+		 *
+		 * This would prevent newport from being recognized
+		 * properly.
+		 *
+		 * This behaviour seems to be specific to the SCSI board,
+		 * since the E++ board does not trigger it. This would
+		 * rule out an HPC1.x-specific cause.
+		 * 
+		 * We work around this by ignoring the topmost byte of id32
+		 * from this point on, but it's ugly and isaish...
+		 *
+		 * Note that this is not necessary on Indigo 2 since this
+		 * troublesome board can not be installed on such a system.
+		 * Indigo are probably safe from this issues, for they can't
+		 * use newport graphics; but the issue at hand might be
+		 * HPC 1.x related, so better play safe.
+		 */
+		if (sys_config.system_type == SGI_IP20 ||
+		    (sys_config.system_type == SGI_IP22 &&
+		     sys_config.system_subtype != IP22_INDIGO2))
+			id32 &= ~0xff000000;
+
 		if (id32 != 4 || id16 != 2 || id8 != 1) {
 			if (guarded_read_4(va + HQ2_MYSTERY, &mystery) == 0 &&
 			    mystery == HQ2_MYSTERY_VALUE)