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

From: "Purushothaman, Vijay A" <vijay.a.purushothaman@linux.intel.com>
To: "Daniel Vetter" <daniel@ffwll.ch>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: Intel Graphics <intel-gfx@lists.freedesktop.org>
Subject: Re: [v2 2/5] drm/i915: Limit max VCO supported in CHV to 6.48GHz
Date: Tue, 03 Mar 2015 20:27:19 +0530	[thread overview]
Message-ID: <54F5CBCF.2030204@linux.intel.com> (raw)
In-Reply-To: <20150223161314.GE24485@phenom.ffwll.local>

On 2/23/2015 9:43 PM, Daniel Vetter wrote:
> On Mon, Feb 16, 2015 at 01:21:34PM +0200, Ville Syrjälä wrote:
>> 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@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.
> Has the updated doc been dug up meanwhile? A big part of review is getting
> access to docs and making sure they're up-to-date too ...
> -Daniel
I sent the copy of excel sheet that i am using to both of you in another 
mail. I still end up relying on windows driver folks since they seem to 
be having latest information about PHY.

Thanks,
Vijay
>> I any case this seems OK, so
>> Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>
>>>   	.n = { .min = 1, .max = 1 },
>>>   	.m1 = { .min = 2, .max = 2 },
>>>   	.m2 = { .min = 24 << 22, .max = 175 << 22 },
>>> -- 
>>> 1.7.9.5
>>>
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx@lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> -- 
>> Ville Syrjälä
>> Intel OTC
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

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