Workaround for /dev/grf3 pixel clock only <29Mhz problem.

[Petri Koistinen <petri.koistinen%iki.fi@localhost>]

Hi!

I found a workaround for the problem with /dev/grf3 that text console
pixel clock could be only under 29Mhz.

Below there is a patch, maybe it could be integrated in the source
tree. It is not complete solution, it just makes it work for me. 
I don´t know if that 58Mhz limit is smart thing, it´s just invented
value.

Are text console modes real hardware text modes, or are they graphics
modes with bitmapped fonts copied on screen. It would explain a lot.

Those who are interessed about Cirrus Logic 5446 databook may look at:
http://iki.fi/thoron/amiga/gd5446trm.lha (pdf, package about 2,3MB).
See page 8-44 (p. 265 in pdf file).

Happy New Year!
Petri Koistinen

--- /sys/arch/amiga/dev/grf_cl.c,old    Wed Dec 20 23:58:03 2000
+++ /sys/arch/amiga/dev/grf_cl.c    Wed Dec 27 17:08:45 2000
@@ -1657,11 +1657,31 @@
         WCrt(ba, CRT_ID_SYNC_ADJ_GENLOCK, 0x00);
         WCrt(ba, CRT_ID_OVERLAY_EXT_CTRL_REG, 0x40);
     }
-    WCrt(ba, CRT_ID_EXT_DISP_CNTL,
-        ((TEXT && gv->pixel_clock > 29000000) ? 0x40 : 0x00) |
-        0x22 |
-        ((HDE > 0xff) ? 0x10 : 0x00));
 
+    /*
+     * Following code tries set fast-page mode after pixel clock
+     * goes over limit. This doesn't work for PicassoIV. Althought
+     * Cirrus Logic claims that 5446 chip can only handle text modes
+     * up to 30Mhz pixel clock, PicassoIV seems to working still with
+     * pixel clock around 58Mhz. After that code will try change to
+     * fast-page mode, but it will fail because there is something
+     * wrong with that code below. (Petri Koistinen, 27.12.2000)
+     *
+     */
+     
+    if ((cltype == PICASSO) && (cl_64bit == 1)) { /* Tested on PIV only. */
+        WCrt(ba, CRT_ID_EXT_DISP_CNTL,
+            ((TEXT && gv->pixel_clock > 58000000) ? 0x40 : 0x00) |
+              0x22 |
+               ((HDE > 0xff) ? 0x10 : 0x00));
+    } 
+    else { /* Other cards may work with original code. */
+        WCrt(ba, CRT_ID_EXT_DISP_CNTL,
+            ((TEXT && gv->pixel_clock > 29000000) ? 0x40 : 0x00) |
+              0x22 |
+               ((HDE > 0xff) ? 0x10 : 0x00));
+    }
+    
     WAttr(ba, ACT_ID_ATTR_MODE_CNTL, (TEXT ? 0x0a : 0x01));
     WAttr(ba, 0x20 | ACT_ID_COLOR_PLANE_ENA,
         (gv->depth == 1) ? 0x01 : 0x0f);