16bpp bugfix for CL-GD7548 Cirrus frame buffer

16bpp bugfix for CL-GD7548 Cirrus frame buffer

Post by Clifford T. Matthew » Mon, 09 Dec 2002 10:20:04



I have a Micron Millennium Transport laptop with Cirrus CL-GD7548
based video.  It works fine in 16bpp using the Cirrus XFree86 4.2.0
driver.  /dev/fb works fine at 8bpp, but didn't work at 16bpp.  I
looked at the two drivers and made clgenfb.c do a few things the
XFree86 driver was doing and now 16bpp appears to work fine on that
laptop.

I don't subscribe to linux-fbdev-devel, but do read lkml via a
leisurely Usenet feed.

--Cliff Matthews        After some people managed to scale the wall,

diff -Naur linux-2.4.20/drivers/video/clgenfb.c linux-2.4.20-clpatch/drivers/video/clgenfb.c
--- linux-2.4.20/drivers/video/clgenfb.c        2002-11-28 16:53:15.000000000 -0700

  *     Lars Hecking:
  *     Amiga updates and testing.
  *

+ *     16bpp fix for CL-GD7548 (uses info from XFree86 4.2.0 source)
+ *
  * Original clgenfb author:  Frank Neumann
  *

 #ifdef CONFIG_PCI
        struct pci_dev *pdev;
+#define IS_7548(x) ((x)->pdev->device == PCI_DEVICE_ID_CIRRUS_7548)
+#else
+#define IS_7548(x) (FALSE)
 #endif
 };

        DPRINTK ("desired pixclock: %ld kHz\n", freq);

-       maxclock = clgen_board_info[fb_info->btype].maxclock;
+       if (IS_7548(fb_info))
+               maxclock = 80100;
+       else
+               maxclock = clgen_board_info[fb_info->btype].maxclock;
        _par->multiplexing = 0;


                case BT_ALPINE:
                        DPRINTK (" (for GD543x)\n");
-                       if (_par->HorizRes >= 1024)
-                               vga_wseq (fb_info->regs, CL_SEQR7, 0xa7);
-                       else
-                               vga_wseq (fb_info->regs, CL_SEQR7, 0xa3);
+                       if (IS_7548(fb_info)) {
+                               vga_wseq (fb_info->regs, CL_SEQR7,
+                                         (vga_rseq (fb_info->regs, CL_SEQR7) & 0xE0)
+                                         | 0x17);
+                               WHDR (fb_info, 0xC1);
+                       } else {
+                               if (_par->HorizRes >= 1024)
+                                       vga_wseq (fb_info->regs, CL_SEQR7, 0xa7);
+                               else
+                                       vga_wseq (fb_info->regs, CL_SEQR7, 0xa3);
+                       }      
                        clgen_set_mclk (fb_info, _par->mclk, _par->divMCLK);
                        break;

                        _par->var.bits_per_pixel);
        }

+       if (IS_7548(fb_info)) {
+               vga_wseq (fb_info->regs, CL_SEQR2D,
+                       vga_rseq (fb_info->regs, CL_SEQR2D) | 0xC0);
+       }
+
        vga_wcrt (fb_info->regs, VGA_CRTC_OFFSET, offset & 0xff);
        tmp = 0x22;
        if (offset & 0x100)
diff -Naur linux-2.4.20/drivers/video/clgenfb.h linux-2.4.20-clpatch/drivers/video/clgenfb.h
--- linux-2.4.20/drivers/video/clgenfb.h        2000-01-06 11:23:46.000000000 -0700

 #define CL_SEQR1D      0x1d    /* VCLK2 Denominator and Post-Scalar Value */
 #define CL_SEQR1E      0x1e    /* VCLK3 Denominator and Post-Scalar Value */
 #define CL_SEQR1F      0x1f    /* BIOS ROM write enable and MCLK Select */
+#define CL_SEQR2D      0x2d    /* unknown, snagged from XFree86 4.2.0 */

 /*** CRT Controller Registers ***/
 #define CL_CRT22       0x22    /* Graphics Data Latches ReadBack */
-
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