[Openchrome-users] X11 Modlines and Meaning for TVout on vt1625 for horizontal position

[Ivor Hewitt]

On Monday 01 May 2006 21:44, Eric Gilbert wrote:
> On 4/29/06, Eric Gilbert <eric.gilbert at gmail.com> wrote:
> [snip]
>
> > At line 795 in via_vt162x.h I see the following being set for register
> > 50-58 which I assume is in hex for for the 720x480Under is defined.
> >
> >  0x0F, 0xCF,  0x23, 0x57, 0x22, 0x59, 0x83, 0x7F, 0x23
> >
> > and translated to decimal I see
> >
> >   15,  207,    35,   87,   34,   89,  131,  127,   35
> >
> > From the output from PrintTVRegs it looks like when I use
> > 720x480Under at 24 with svn181 the HTP (Horizontal Total Pixels) is 89
> > with the HAP (Horizontal Active Pixels) 131 and the HSW (Horizontal
> > Sync Width) is 127. Why would the HTP be less than the HPA and why is
> > the HSW so large?
>
> I'm a dipsh*t and spaced on the whole bits to hex to decimal
> conversions ... and I think I have an actual reasonable(albeit
> seemingly dumb) question.
>
> After more review of this section I think I want to try to set
> registers 50-58 to
>
> 0x310,0x2D0,  0x20,0x258, 0x22, 0x310, 0x2D0, 0x7F, 0x23
>
> but when I compile that change I get
>
> warning: large integer implicitly truncated to unsigned type
>
> for registers 50,51,53,55,56
>
> which are written in via_vt162x.c:634:
> xf86I2CWriteByte(pBIOSInfo->TVI2CDev, 0x4A + i, Table.TV2[i]);
>
> and the table element is defined in via_vt162x.h:199 with
> CARD8  TV2[0x1B];
>
> So my question is, should this be defined as a CARD16 so that it can
> take the larger values and should this be written with
> xf86I2CWriteBytes or xf86I2CWriteWord or something else entirely so
> that the whole value is written to the register?
>
It's a trifle more complex than that I'm afraid. Each register is just 1 byte 
and so large values are either split over multiple registers or scaled down 
by various factors.

Perhaps a better way of approaching this is to ask.... what is the current 
problem with the vt1625 tv modes?
Which ones don't work?

Regards,

-- 
Ivor Hewitt.