[Intel-gfx] [v2 2/5] drm/i915: Limit max VCO supported in CHV to 6.48GHz

[Ville Syrjälä]

On Mon, Feb 16, 2015 at 03:07:59PM +0530, Vijay Purushothaman wrote:
> As per the recommendation from PHY team, limit the max vco supported in CHV to 6.48 GHz
> 
> Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 3b0fe9f..4e710f6 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -390,7 +390,7 @@ static const intel_limit_t intel_limits_chv = {
>  	 * them would make no difference.
>  	 */
>  	.dot = { .min = 25000 * 5, .max = 540000 * 5},
> -	.vco = { .min = 4860000, .max = 6700000 },
> +	.vco = { .min = 4860000, .max = 6480000 },

I have a patch here to reduce the minimum to 4.80 GHz, otherwise I can't
get my 2560x1440 HDMI display working (241.5 MHz clock). With that change
we still have a gap (233-240 MHz) in the frequencies we can produce.
Reducing the max to 6.48 GHz will increase that gap to 216-240 MHz, which
is a bit unfortunate. But if that's the recommendation we should follow
it I suppose, and hope no HDMI displays will want such frequencies.

Is there an updated spreadsheet available with the new limits? Quite a
few of the frequencies in the original spreadsheet did have vco>6.48
GHz.

I any case this seems OK, so
Acked-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

>  	.n = { .min = 1, .max = 1 },
>  	.m1 = { .min = 2, .max = 2 },
>  	.m2 = { .min = 24 << 22, .max = 175 << 22 },
> -- 
> 1.7.9.5
> 
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-- 
Ville Syrjälä
Intel OTC