gma500_gfx: spread spectrum clocking?

gma500_gfx: spread spectrum clocking?

[George McCollister]

emgd had an option to enable spread spectrum clocking on LVDS. The
documentation is vague but the setting that works is:
Option     "ALL/1/Port/4/Attr/43"    "7"

Anyone have any idea how to set this with gma500_gfx or if it doesn't
support it, how to put the hardware in this mode?

Thanks,
George McCollister
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Re: gma500_gfx: spread spectrum clocking?

[George McCollister]

Looks like these are the magic bits that need to be set:

dpll |= (7<<9) | (1<<13) | (1<<14);

Anyone happen to have proper descriptions for these bits so I could
add them to psb_intel_reg.h or thoughts on how/where an option could
be exposed to enable these?

On Mon, Apr 6, 2015 at 4:48 PM, George McCollister
<george.mccollister@gmail.com> wrote:
> emgd had an option to enable spread spectrum clocking on LVDS. The
> documentation is vague but the setting that works is:
> Option     "ALL/1/Port/4/Attr/43"    "7"
>
> Anyone have any idea how to set this with gma500_gfx or if it doesn't
> support it, how to put the hardware in this mode?
>
> Thanks,
> George McCollister
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Re: gma500_gfx: spread spectrum clocking?

[Ilia Mirkin]

On Tue, Apr 7, 2015 at 3:29 PM, George McCollister
<george.mccollister@gmail.com> wrote:
> Looks like these are the magic bits that need to be set:
>
> dpll |= (7<<9) | (1<<13) | (1<<14);
>
> Anyone happen to have proper descriptions for these bits so I could
> add them to psb_intel_reg.h or thoughts on how/where an option could
> be exposed to enable these?

FWIW in nouveau, we tend to call things like that UNK09, UNK0D, UNK0E.
Or just throw the constant in directly to make it easier to compare to
traces.

  -ilia
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