>Number:         23399
>Category:       port-sparc
>Synopsis:       sys/dev/sbus/zx* is unnecessarily sketchy
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-sparc-maintainer
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sun Nov 09 18:49:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     der Mouse
>Release:        -current as of 2003-11-09
>Organization:
	Dis-
>Environment:
	Any SPARC with a zx ("SUNW,leo")
>Description:
	sys/dev/sbus/zx* has a number of unknown things (search zxreg.h
	for UNK) and magic numbers (look at zx_reset's calls to
	zx_cross_loadwid, for example).  These need not be unknown; I
	have documentation on the leo that's detailed enough to explain
	them.
>How-To-Repeat:
	Look at the code.
>Fix:
	I have documentation enough to fix these.  Unfortunately it's
	in the form of HTML files; I have distilled them down into a
	text file, but the text file is intended for my own reference
	rather than as full documentation.

	The whole thing is up for anonymous ftp from
	sparkle.rodents.montreal.qc.ca:/mouse/docs/Sun/ZX/;
	notes/mouse-notes.txt is the aforementioned text file, with
	index.html being the root of the HTML docs.

	I spent a little while looking for where I got these HTML files
	from, but I found nothing answering that question.  (Googling
	for quotes finds no hits, for example.)

	Specifically:

	#define ZX_OFF_UNK2             0x00000000
	This is boot PROM space.

	#define ZX_OFF_UNK              0x00602000
	This is the video frame counter register.

	#define ZX_CROSS_TYPE_UNK       0x00001006
	This is an interrupt enable mask.

	#define ZX_CROSS_CSR_UNK        0x00000002
	#define ZX_CROSS_CSR_UNK2       0x00000001
	These are the WID LUT Transfer Command (UNK) and WID LUT
	Transfer Direction (UNK2) bits.

	zx_cross_wait is rather misnamed; it is wait-for-completion
	only for LUT transfers.

	The magic numbers in the cursor code are explained.  I also
	suspect there's a bug; I think 0x20<<j in zx_cursor_set should
	be 0x20*j, according to the doc.

	zx_cursor_color needs to do something analogous to
	zx_cross_wait().

	Most of the pad areas in the structs have things in them, but
	it would be way too lengthy to fill them all in here.

	LUT transfers do not use the recommended procedure of
	withdrawing a previous transfer request if present.  This
	mostly matters in that it may mean delaying some transfers by
	more vertical blanking intervals than necessary.  Since the
	delay is done by busy-waiting in the kernel, this is not good.

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>Release-Note:
>Audit-Trail:
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