GSoC: modprobe glint - monitor loses signal

[Adam Jackson]

On Thu, 2010-08-05 at 12:16 -0400, Matt Turner wrote:
> Hi,
> I've hit a snag and I'm not really sure how to debug it.
> 
> Both xf86-video-glint/src/pm3_dac.c:Permedia3Init and
> kernel/drivers/video/pm3fb.c:pm3fb_write_mode set the mode in
> virtually identical ways. I'm trying to do the same, but I think some
> of what I'm passing in from drm_display_mode is wrong, specifically
> 
> WREG32(PM3HTotal,  glint_shift_bpp(bpp, mode->htotal - 1));
> WREG32(PM3HsEnd,   glint_shift_bpp(bpp, mode->hsync_end - mode->hdisplay));
> WREG32(PM3HsStart, glint_shift_bpp(bpp, mode->hsync_start - mode->hdisplay));
> WREG32(PM3HbEnd,   glint_shift_bpp(bpp, mode->htotal - mode->hdisplay));
> WREG32(PM3HgEnd,   glint_shift_bpp(bpp, mode->htotal - mode->hdisplay));
> WREG32(PM3ScreenStride, glint_shift_bpp(bpp, crtc->fb->width));
> WREG32(PM3VTotal,  glint_shift_bpp(bpp, mode->vtotal - 1));
> WREG32(PM3VsEnd,   glint_shift_bpp(bpp, mode->vsync_end - 1));
> WREG32(PM3VsStart, glint_shift_bpp(bpp, mode->vsync_start - 1));
> WREG32(PM3VbEnd,   glint_shift_bpp(bpp, mode->vtotal - mode->vdisplay));
>
> I printed the values that xf86-video-glint passes through here, and of
> course they don't match with anything my driver has. I imagine guess
> it's because they're all resolution-dependent?

They are.  What does the X driver print, and what mode are you trying to
set?

This though:

    WREG32(PM3VsStart, glint_shift_bpp(bpp, mode->vsync_start - 1));

Versus in the X driver:

    temp2 = mode->CrtcVSyncStart - mode->CrtcVDisplay;
    ...
    STOREREG(PMVsStart, temp2 - 1);

For a mode like 1920x1200R, the former is going to be 1202, but the
latter is going to be (1203 - 1200) - 1 == 2.  So assuming the X driver
is right, the hardware is looking for the distance in clocks between the
various sync steps, and not their absolute offset from the beginning of
the line/frame.

- ajax
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