9front - general discussion about 9front
 help / color / mirror / Atom feed
From: Michael Forney <mforney@mforney.org>
To: 9front@9front.org
Subject: [9front] [PATCH] aux/vga: return modes according to EDID timing priority order
Date: Mon, 28 Feb 2022 13:20:52 -0800	[thread overview]
Message-ID: <20220228212052.16195-1-mforney@mforney.org> (raw)


EDID 1.3 section 5 gives a table describing the priority order of
timing information. Use this ordering when constructing the EDID
mode list.

Since aux/vga selects the first mode in the modelist that matches
the given size, it will now select the mode of that size with the
highest preference. Or, if you set vgasize=auto (or some other
string without an 'x'), aux/vga will select the Preferred Detailed
Timing.

This should make it unnecessary to modify vgadb in many cases.
---
 sys/src/cmd/aux/vga/edid.c | 133 ++++++++++++++++++++-----------------
 1 file changed, 73 insertions(+), 60 deletions(-)

diff --git a/sys/src/cmd/aux/vga/edid.c b/sys/src/cmd/aux/vga/edid.c
index d475678fe..09a0acbbc 100644
--- a/sys/src/cmd/aux/vga/edid.c
+++ b/sys/src/cmd/aux/vga/edid.c
@@ -6,8 +6,8 @@
 #include "pci.h"
 #include "vga.h"
 
-static Modelist*
-addmode(Modelist *l, Mode m)
+static void
+addmode(Modelist **l, Mode m)
 {
 	Modelist *ll;
 	int rr;
@@ -15,17 +15,15 @@ addmode(Modelist *l, Mode m)
 	rr = (m.frequency+m.ht*m.vt/2)/(m.ht*m.vt);
 	snprint(m.name, sizeof m.name, "%dx%d@%dHz", m.x, m.y, rr);
 
-	for(ll = l; ll != nil; ll = ll->next){
-		if(strcmp(ll->name, m.name) == 0){
-			ll->Mode = m;
-			return l;
-		}
+	for(ll = *l; ll != nil; ll = *l){
+		if(strcmp(ll->name, m.name) == 0)
+			return;
+		l = &ll->next;
 	}
 
 	ll = alloc(sizeof(Modelist));
 	ll->Mode = m;
-	ll->next = l;
-	return ll;
+	*l = ll;
 }
 
 /*
@@ -282,70 +280,85 @@ parseedid128(void *v)
 
 	assert(p == (uchar*)v+8+10+2+5+10);
 	/*
-	 * Established timings: a bitmask of 19 preset timings.
+	 * Timing information priority order (EDID 1.3 section 5)
+	 *   1. Preferred Timing Mode (first detailed timing block)
+	 *   2. Other Detailed Timing Mode, in order listed
+	 *   3. Standard Timings, in order listed
+	 *   4. Established Timings
 	 */
-	estab = (p[0]<<16) | (p[1]<<8) | p[2];
-	p += 3;
 
-	for(i=0, m=1<<23; i<nelem(estabtime); i++, m>>=1)
-		if(estab & m)
-			if(vesalookup(&mode, estabtime[i]) == 0)
-				e->modelist = addmode(e->modelist,  mode);
+	/*
+	 * Detailed Timings
+	 */
+	p = (uchar*)v+8+10+2+5+10+3+16;
+	for(i=0; i<4; i++, p+=18)
+		if(p[0] || p[1])	/* detailed timing block: p[0] or p[1] != 0 */
+			if(decodedtb(&mode, p) == 0)
+				addmode(&e->modelist, mode);
+	assert(p == (uchar*)v+8+10+2+5+10+3+16+72);
 
-	assert(p == (uchar*)v+8+10+2+5+10+3);
 	/*
 	 * Standard Timing Identifications: eight 2-byte selectors
 	 * of more standard timings.
 	 */
-
+	p = (uchar*)v+8+10+2+5+10+3;
 	for(i=0; i<8; i++, p+=2)
 		if(decodesti(&mode, p+2*i) == 0)
-			e->modelist = addmode(e->modelist, mode);
-
+			addmode(&e->modelist, mode);
 	assert(p == (uchar*)v+8+10+2+5+10+3+16);
-	/*
-	 * Detailed Timings
-	 */
-	for(i=0; i<4; i++, p+=18) {
-		if(p[0] || p[1]) {	/* detailed timing block: p[0] or p[1] != 0 */
-			if(decodedtb(&mode, p) == 0)
-				e->modelist = addmode(e->modelist, mode);
-		} else if(p[2]==0) {	/* monitor descriptor block */
-			switch(p[3]) {
-			case 0xFF:	/* monitor serial number (13-byte ascii, 0A terminated) */
-				if(q = memchr(p+5, 0x0A, 13))
-					*q = '\0';
-				memset(e->serialstr, 0, sizeof(e->serialstr));
-				strncpy(e->serialstr, (char*)p+5, 13);
-				break;
-			case 0xFE:	/* ascii string (13-byte ascii, 0A terminated) */
-				break;
-			case 0xFD:	/* monitor range limits */
-				e->rrmin = p[5];
-				e->rrmax = p[6];
-				e->hrmin = p[7]*1000;
-				e->hrmax = p[8]*1000;
-				if(p[9] != 0xFF)
-					e->pclkmax = p[9]*10*1000000;
-				break;
-			case 0xFC:	/* monitor name (13-byte ascii, 0A terminated) */
-				if(q = memchr(p+5, 0x0A, 13))
-					*q = '\0';
-				memset(e->name, 0, sizeof(e->name));
-				strncpy(e->name, (char*)p+5, 13);
-				break;
-			case 0xFB:	/* extra color point data */
-				break;
-			case 0xFA:	/* extra standard timing identifications */
-				for(i=0; i<6; i++)
-					if(decodesti(&mode, p+5+2*i) == 0)
-						e->modelist = addmode(e->modelist, mode);
-				break;
-			}
+
+	p = (uchar*)v+8+10+2+5+10+3+16;
+	for(i=0; i<4; i++, p+=18){
+		if(p[0] || p[1])
+			continue;
+		/* monitor descriptor block */
+		switch(p[3]) {
+		case 0xFF:	/* monitor serial number (13-byte ascii, 0A terminated) */
+			if(q = memchr(p+5, 0x0A, 13))
+				*q = '\0';
+			memset(e->serialstr, 0, sizeof(e->serialstr));
+			strncpy(e->serialstr, (char*)p+5, 13);
+			break;
+		case 0xFE:	/* ascii string (13-byte ascii, 0A terminated) */
+			break;
+		case 0xFD:	/* monitor range limits */
+			e->rrmin = p[5];
+			e->rrmax = p[6];
+			e->hrmin = p[7]*1000;
+			e->hrmax = p[8]*1000;
+			if(p[9] != 0xFF)
+				e->pclkmax = p[9]*10*1000000;
+			break;
+		case 0xFC:	/* monitor name (13-byte ascii, 0A terminated) */
+			if(q = memchr(p+5, 0x0A, 13))
+				*q = '\0';
+			memset(e->name, 0, sizeof(e->name));
+			strncpy(e->name, (char*)p+5, 13);
+			break;
+		case 0xFB:	/* extra color point data */
+			break;
+		case 0xFA:	/* extra standard timing identifications */
+			for(i=0; i<6; i++)
+				if(decodesti(&mode, p+5+2*i) == 0)
+					addmode(&e->modelist, mode);
+			break;
 		}
 	}
-
 	assert(p == (uchar*)v+8+10+2+5+10+3+16+72);
+
+	/*
+	 * Established timings: a bitmask of 19 preset timings.
+	 */
+	p = (uchar*)v+8+10+2+5+10;
+	estab = (p[0]<<16) | (p[1]<<8) | p[2];
+	p += 3;
+
+	for(i=0, m=1<<23; i<nelem(estabtime); i++, m>>=1)
+		if(estab & m)
+			if(vesalookup(&mode, estabtime[i]) == 0)
+				addmode(&e->modelist, mode);
+	assert(p == (uchar*)v+8+10+2+5+10+3);
+
 	return e;
 }
 
-- 
2.34.1


             reply	other threads:[~2022-02-28 21:32 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-28 21:20 Michael Forney [this message]
2022-02-28 22:06 ` Steve Simon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220228212052.16195-1-mforney@mforney.org \
    --to=mforney@mforney.org \
    --cc=9front@9front.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).