public inbox for linux-fbdev@vger.kernel.org
 help / color / mirror / Atom feed
From: Daniel Palmer <daniel@thingy.jp>
To: deller@gmx.de, linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	Daniel Palmer <daniel@thingy.jp>
Subject: [PATCH] fbdev/tdfxfb: Make the VGA register initialisation a bit more obvious
Date: Fri, 27 Feb 2026 21:25:00 +0900	[thread overview]
Message-ID: <20260227122500.3885069-1-daniel@thingy.jp> (raw)

For a while I was trying to get this working on m68k, for some reason
the card doesn't display anything if it's own video BIOS didn't run..

Anyhow, I spent a long time looking up what each of these offsets
were to work out what the code is configuring and eventually
replaced them with the human readable defines in video/vga.h.

Functionally there is no change but maybe it makes it a bit easier to
look at for the next person that finds themselves in here.

Tested on a real voodoo 3 on x86_64.

Signed-off-by: Daniel Palmer <daniel@thingy.jp>
---
 drivers/video/fbdev/tdfxfb.c | 109 ++++++++++++++++++-----------------
 1 file changed, 55 insertions(+), 54 deletions(-)

diff --git a/drivers/video/fbdev/tdfxfb.c b/drivers/video/fbdev/tdfxfb.c
index 51ebe78359ec..7606e024fa3f 100644
--- a/drivers/video/fbdev/tdfxfb.c
+++ b/drivers/video/fbdev/tdfxfb.c
@@ -77,6 +77,7 @@
 #include <asm/io.h>
 
 #include <video/tdfx.h>
+#include <video/vga.h>
 
 #define DPRINTK(a, b...) pr_debug("fb: %s: " a, __func__ , ## b)
 
@@ -591,7 +592,7 @@ static int tdfxfb_set_par(struct fb_info *info)
 		vt = ve + (info->var.upper_margin << 1) - 1;
 		reg.screensize = info->var.xres | (info->var.yres << 13);
 		reg.vidcfg |= VIDCFG_HALF_MODE;
-		reg.crt[0x09] = 0x80;
+		reg.crt[VGA_CRTC_MAX_SCAN] = 0x80;
 	} else {
 		vd = info->var.yres - 1;
 		vs  = vd + info->var.lower_margin;
@@ -609,59 +610,59 @@ static int tdfxfb_set_par(struct fb_info *info)
 			 info->var.xres < 480 ? 0x60 :
 			 info->var.xres < 768 ? 0xe0 : 0x20);
 
-	reg.gra[0x05] = 0x40;
-	reg.gra[0x06] = 0x05;
-	reg.gra[0x07] = 0x0f;
-	reg.gra[0x08] = 0xff;
-
-	reg.att[0x00] = 0x00;
-	reg.att[0x01] = 0x01;
-	reg.att[0x02] = 0x02;
-	reg.att[0x03] = 0x03;
-	reg.att[0x04] = 0x04;
-	reg.att[0x05] = 0x05;
-	reg.att[0x06] = 0x06;
-	reg.att[0x07] = 0x07;
-	reg.att[0x08] = 0x08;
-	reg.att[0x09] = 0x09;
-	reg.att[0x0a] = 0x0a;
-	reg.att[0x0b] = 0x0b;
-	reg.att[0x0c] = 0x0c;
-	reg.att[0x0d] = 0x0d;
-	reg.att[0x0e] = 0x0e;
-	reg.att[0x0f] = 0x0f;
-	reg.att[0x10] = 0x41;
-	reg.att[0x12] = 0x0f;
-
-	reg.seq[0x00] = 0x03;
-	reg.seq[0x01] = 0x01; /* fixme: clkdiv2? */
-	reg.seq[0x02] = 0x0f;
-	reg.seq[0x03] = 0x00;
-	reg.seq[0x04] = 0x0e;
-
-	reg.crt[0x00] = ht - 4;
-	reg.crt[0x01] = hd;
-	reg.crt[0x02] = hbs;
-	reg.crt[0x03] = 0x80 | (hbe & 0x1f);
-	reg.crt[0x04] = hs;
-	reg.crt[0x05] = ((hbe & 0x20) << 2) | (he & 0x1f);
-	reg.crt[0x06] = vt;
-	reg.crt[0x07] = ((vs & 0x200) >> 2) |
-			((vd & 0x200) >> 3) |
-			((vt & 0x200) >> 4) | 0x10 |
-			((vbs & 0x100) >> 5) |
-			((vs & 0x100) >> 6) |
-			((vd & 0x100) >> 7) |
-			((vt & 0x100) >> 8);
-	reg.crt[0x09] |= 0x40 | ((vbs & 0x200) >> 4);
-	reg.crt[0x10] = vs;
-	reg.crt[0x11] = (ve & 0x0f) | 0x20;
-	reg.crt[0x12] = vd;
-	reg.crt[0x13] = wd;
-	reg.crt[0x15] = vbs;
-	reg.crt[0x16] = vbe + 1;
-	reg.crt[0x17] = 0xc3;
-	reg.crt[0x18] = 0xff;
+	reg.gra[VGA_GFX_MODE]         = 0x40;
+	reg.gra[VGA_GFX_MISC]         = 0x05;
+	reg.gra[VGA_GFX_COMPARE_MASK] = 0x0f;
+	reg.gra[VGA_GFX_BIT_MASK]     = 0xff;
+
+	reg.att[VGA_ATC_PALETTE0]     = 0x00;
+	reg.att[VGA_ATC_PALETTE1]     = 0x01;
+	reg.att[VGA_ATC_PALETTE2]     = 0x02;
+	reg.att[VGA_ATC_PALETTE3]     = 0x03;
+	reg.att[VGA_ATC_PALETTE4]     = 0x04;
+	reg.att[VGA_ATC_PALETTE5]     = 0x05;
+	reg.att[VGA_ATC_PALETTE6]     = 0x06;
+	reg.att[VGA_ATC_PALETTE7]     = 0x07;
+	reg.att[VGA_ATC_PALETTE8]     = 0x08;
+	reg.att[VGA_ATC_PALETTE9]     = 0x09;
+	reg.att[VGA_ATC_PALETTEA]     = 0x0a;
+	reg.att[VGA_ATC_PALETTEB]     = 0x0b;
+	reg.att[VGA_ATC_PALETTEC]     = 0x0c;
+	reg.att[VGA_ATC_PALETTED]     = 0x0d;
+	reg.att[VGA_ATC_PALETTEE]     = 0x0e;
+	reg.att[VGA_ATC_PALETTEF]     = 0x0f;
+	reg.att[VGA_ATC_MODE]         = 0x41;
+	reg.att[VGA_ATC_PLANE_ENABLE] = 0x0f;
+
+	reg.seq[VGA_SEQ_RESET]         = 0x03;
+	reg.seq[VGA_SEQ_CLOCK_MODE]    = 0x01; /* fixme: clkdiv2? */
+	reg.seq[VGA_SEQ_PLANE_WRITE]   = 0x0f;
+	reg.seq[VGA_SEQ_CHARACTER_MAP] = 0x00;
+	reg.seq[VGA_SEQ_MEMORY_MODE]   = 0x0e;
+
+	reg.crt[VGA_CRTC_H_TOTAL]       = ht - 4;
+	reg.crt[VGA_CRTC_H_DISP]        = hd;
+	reg.crt[VGA_CRTC_H_BLANK_START] = hbs;
+	reg.crt[VGA_CRTC_H_BLANK_END]   = 0x80 | (hbe & 0x1f);
+	reg.crt[VGA_CRTC_H_SYNC_START]  = hs;
+	reg.crt[VGA_CRTC_H_SYNC_END]    = ((hbe & 0x20) << 2) | (he & 0x1f);
+	reg.crt[VGA_CRTC_V_TOTAL]       = vt;
+	reg.crt[VGA_CRTC_OVERFLOW]      = ((vs & 0x200) >> 2) |
+					  ((vd & 0x200) >> 3) |
+					  ((vt & 0x200) >> 4) | 0x10 |
+					  ((vbs & 0x100) >> 5) |
+					  ((vs & 0x100) >> 6) |
+					  ((vd & 0x100) >> 7) |
+					  ((vt & 0x100) >> 8);
+	reg.crt[VGA_CRTC_MAX_SCAN]     |= 0x40 | ((vbs & 0x200) >> 4);
+	reg.crt[VGA_CRTC_V_SYNC_START]  = vs;
+	reg.crt[VGA_CRTC_V_SYNC_END]    = (ve & 0x0f) | 0x20;
+	reg.crt[VGA_CRTC_V_DISP_END]    = vd;
+	reg.crt[VGA_CRTC_OFFSET]        = wd;
+	reg.crt[VGA_CRTC_V_BLANK_START] = vbs;
+	reg.crt[VGA_CRTC_V_BLANK_END]   = vbe + 1;
+	reg.crt[VGA_CRTC_MODE]          = 0xc3;
+	reg.crt[VGA_CRTC_LINE_COMPARE]  = 0xff;
 
 	/* Banshee's nonvga stuff */
 	reg.ext[0x00] = (((ht & 0x100) >> 8) |
-- 
2.51.0


             reply	other threads:[~2026-02-27 12:25 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-27 12:25 Daniel Palmer [this message]
2026-02-27 14:27 ` [PATCH] fbdev/tdfxfb: Make the VGA register initialisation a bit more obvious Helge Deller

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=20260227122500.3885069-1-daniel@thingy.jp \
    --to=daniel@thingy.jp \
    --cc=deller@gmx.de \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=linux-fbdev@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.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