[GMA500] Valid VCO frequency range on GMA500 platform?

[GMA500] Valid VCO frequency range on GMA500 platform?

["David Müller (ELSOFT AG)"]

Hello

I have a problem using a 1024x768 Eizo Monitor attached by DVI-D to a
system with GMA500 based graphics and running under Linux-3.7.

As soon as the GMA500 driver is taking over control, the refresh
rate raises to 64.5Hz and the monitor reports a "signal error".

For me i looks like the GMA500 driver is reprogramming the VCO to a too
high dot clock. If i lower the "I9XX_VCO_MIN" value to 1300000,
everything is fine.

Is the "I9XX_VCO_MIN" value used in the GMA500 driver correct?


Dave

Re: [GMA500] Valid VCO frequency range on GMA500 platform?

[Patrik Jakobsson]

On Fri, Feb 8, 2013 at 2:51 PM, "David Müller (ELSOFT AG)"
<d.mueller@elsoft.ch> wrote:
>
> Hello
>
> I have a problem using a 1024x768 Eizo Monitor attached by DVI-D to a
> system with GMA500 based graphics and running under Linux-3.7.
>
> As soon as the GMA500 driver is taking over control, the refresh
> rate raises to 64.5Hz and the monitor reports a "signal error".
>
> For me i looks like the GMA500 driver is reprogramming the VCO to a too
> high dot clock. If i lower the "I9XX_VCO_MIN" value to 1300000,
> everything is fine.
>
> Is the "I9XX_VCO_MIN" value used in the GMA500 driver correct?
>
>
> Dave

Hi Dave
The value of VCO_MIN comes from the Intel PRM for similar GPUs.

Instead of changing VCO_MIN, could you try setting N_MIN=1, N_MAX=6 and
M1_MAX=22? I'll test it on my own hardware tomorrow.

-Patrik

Re: [GMA500] Valid VCO frequency range on GMA500 platform?

["David Müller (ELSOFT AG)"]

Hi Patrik

Patrik Jakobsson wrote:
> The value of VCO_MIN comes from the Intel PRM for similar GPUs.
> 
> Instead of changing VCO_MIN, could you try setting N_MIN=1, N_MAX=6 and
> M1_MAX=22? I'll test it on my own hardware tomorrow.

Thanks for your suggestion.

With "N_MIN=1, N_MAX=6 and M1_MAX=22", i get a refresh rate of 59.9Hz.


Dave

Re: [GMA500] Valid VCO frequency range on GMA500 platform?

[Patrik Jakobsson]

On Mon, Feb 11, 2013 at 2:15 PM, "David Müller (ELSOFT AG)"
<d.mueller@elsoft.ch> wrote:
> Hi Patrik
>
> Patrik Jakobsson wrote:
>> The value of VCO_MIN comes from the Intel PRM for similar GPUs.
>>
>> Instead of changing VCO_MIN, could you try setting N_MIN=1, N_MAX=6 and
>> M1_MAX=22? I'll test it on my own hardware tomorrow.
>
> Thanks for your suggestion.
>
> With "N_MIN=1, N_MAX=6 and M1_MAX=22", i get a refresh rate of 59.9Hz.
>
>
> Dave
>

Those values come from the i915 driver and should work fine for us as well.
I had no problems at my end so I'll submit a patch for this.

-Patrik

Re: [GMA500] Valid VCO frequency range on GMA500 platform?

[Patrik Jakobsson]

On Mon, Feb 11, 2013 at 11:18 PM, Patrik Jakobsson
<patrik.r.jakobsson@gmail.com> wrote:
> On Mon, Feb 11, 2013 at 2:15 PM, "David Müller (ELSOFT AG)"
> <d.mueller@elsoft.ch> wrote:
>> Hi Patrik
>>
>> Patrik Jakobsson wrote:
>>> The value of VCO_MIN comes from the Intel PRM for similar GPUs.
>>>
>>> Instead of changing VCO_MIN, could you try setting N_MIN=1, N_MAX=6 and
>>> M1_MAX=22? I'll test it on my own hardware tomorrow.
>>
>> Thanks for your suggestion.
>>
>> With "N_MIN=1, N_MAX=6 and M1_MAX=22", i get a refresh rate of 59.9Hz.
>>
>>
>> Dave
>>
>
> Those values come from the i915 driver and should work fine for us as well.
> I had no problems at my end so I'll submit a patch for this.
>
> -Patrik

I've sent in a patch for this:
http://lists.freedesktop.org/archives/dri-devel/2013-February/034990.html
it is slightly different to what I proposed earlier. Would be nice if you could
give it a spin and report back.

Thanks
Patrik

Re: [GMA500] Valid VCO frequency range on GMA500 platform?

["David Müller (ELSOFT AG)"]

Patrik Jakobsson wrote:

> I've sent in a patch for this:
> http://lists.freedesktop.org/archives/dri-devel/2013-February/034990.html
> it is slightly different to what I proposed earlier. Would be nice if you could
> give it a spin and report back.


Seems to be ok.

Tested-by: <d.mueller@elsoft.ch>