Re: [PATCH] drm/i915/skl: Init cdclk in the driver rather than relying on pre-os

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 05 Oct 2015, Imre Deak <imre.deak@intel.com> wrote:
> On ma, 2015-10-05 at 20:52 +0530, Shobhit Kumar wrote:
>> Mostly reuse what is programmed by pre-os, but in case there is no
>> pre-os initialization, init the cdclk with the default value.
>> 
>> Cc: Imre Deak <imre.deak@intel.com>
>> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_ddi.c | 6 ++----
>>  1 file changed, 2 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
>> index 2d3cc82..675c60d 100644
>> --- a/drivers/gpu/drm/i915/intel_ddi.c
>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
>> @@ -2947,10 +2947,8 @@ void intel_ddi_pll_init(struct drm_device *dev)
>>  
>>  		cdclk_freq = dev_priv->display.get_display_clock_speed(dev);
>>  		dev_priv->skl_boot_cdclk = cdclk_freq;
>> -		if (!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_ENABLE))
>> -			DRM_ERROR("LCPLL1 is disabled\n");
>> -		else
>> -			intel_display_power_get(dev_priv, POWER_DOMAIN_PLLS);
>> +
>> +		skl_init_cdclk(dev_priv);
>
> How does this prevent changing the clock if BIOS did enable some output?
> We shouldn't change the clock in that case.

Random comment from the back, what about intentional cdclk change on
module load? We're supposed to have that for bdw [1] but last I checked
it failed... [2].

BR,
Jani.

[1] http://mid.gmane.org/1433335514-4156-8-git-send-email-mika.kahola@intel.com
[2] http://mid.gmane.org/87bngf4xk3.fsf@intel.com


>
>>  	} else if (IS_BROXTON(dev)) {
>>  		broxton_init_cdclk(dev);
>>  		broxton_ddi_phy_init(dev);
>
>

-- 
Jani Nikula, Intel Open Source Technology Center
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