Re: [v3] drm/i915/skl: If needed sanitize bios programmed cdclk

["Kumar, Shobhit" <shobhit.kumar@linux.intel.com>]

On 10/19/2015 07:18 PM, Ville Syrjälä wrote:
> On Fri, Oct 16, 2015 at 06:48:53PM +0530, Shobhit Kumar wrote:
>> Especially in cases where pre-os does not enable display, cdclk might
>> not be in sane state. During sanitization initialize cdclk with maximum
>> value till we get dynamic cdclk support.
>>
>> v2: Check if BIOS programmed correctly rather than always calling init
>>      - Do validation of programmed cdctl and what it is expected
>>      - Only do slk_init_cdclk if validation failed else reuse BIOS
>>        programmed value
>>
>> v3: Move the validation logic in a separate sanitize function (Ville)
>>
>> Cc: Imre Deak <imre.deak@intel.com>
>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_ddi.c     | 12 ++++++++----
>>   drivers/gpu/drm/i915/intel_display.c | 31 +++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/i915/intel_drv.h     |  1 +
>>   3 files changed, 40 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
>> index b25e99a..86d43e6 100644
>> --- a/drivers/gpu/drm/i915/intel_ddi.c
>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
>> @@ -2949,10 +2949,14 @@ 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);
>> +		if (skl_sanitize_cdclk(dev_priv))
>> +			DRM_DEBUG_KMS("Sanitized cdclk programmed by pre-os\n");
>> +		else {
>> +			if (!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_ENABLE))
>> +				DRM_ERROR("LCPLL1 is disabled\n");
>
> Since skl_sanitize_cdclk() will enable the PLL this shouldn't
> happen anymore, right?
>

Yeah right. Will remove.

>> +			else
>> +				intel_display_power_get(dev_priv, POWER_DOMAIN_PLLS);
>> +		}
>>   	} else if (IS_BROXTON(dev)) {
>>   		broxton_init_cdclk(dev);
>>   		broxton_ddi_phy_init(dev);
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 5f37f84..98333d3 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -5784,6 +5784,37 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv)
>>   		DRM_ERROR("DBuf power enable timeout\n");
>>   }
>>
>> +int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
>> +{
>> +	uint32_t lcpll1 = I915_READ(LCPLL1_CTL);
>> +	uint32_t cdctl = I915_READ(CDCLK_CTL);
>> +	int freq = dev_priv->skl_boot_cdclk;
>> +
>> +	/* Is PLL enabled and locked ? */
>> +	if (!((lcpll1 & LCPLL_PLL_ENABLE) && (lcpll1 & LCPLL_PLL_LOCK)))
>> +		goto sanitize;
>> +
>> +	/* DPLL okay; verify the cdclock
>> +	 *
>> +	 * Noticed in some instances that the freq selection is correct but
>> +	 * decimal part is programmed wrong from BIOS where pre-os does not
>> +	 * enable display. Verify the same as well.
>> +	 */
>> +	if (cdctl == ((cdctl & CDCLK_FREQ_SEL_MASK) | skl_cdclk_decimal(freq)))
>> +		/* All well; nothing to sanitize */
>> +		return false;
>> +sanitize:
>> +	/*
>> +	 * As of now initialize with max cdclk till
>> +	 * we get dynamic cdclk support
>> +	 * */
>> +	dev_priv->skl_boot_cdclk = 675000;
>
> Should be '= dev_priv->max_cdclk'
>
> I think we end up doing the intel_update_cdclk() before this gets
> called, so max_cdclk should already contain something sensible. The
> whole init sequence is a bit messy currently, but I think we can put
> off cleaning it up after the dc6 stuff gets sorted.
>

Actually at the end of skl_init_cdclock, intel_update_cdclk will be 
called and initialize the max_cdclk correctly. In case there was no 
sanitization needed, the BIOS programmed cdclk is stored in 
skl_boot_cdclk and that is used inside the skl_init_cdclk. Same is 
invoked resume time, so we need to update this variable or else change 
the logic.

>> +	skl_init_cdclk(dev_priv);
>> +
>> +	/* we did have to sanitize */
>> +	return true;
>> +}
>> +
>>   /* Adjust CDclk dividers to allow high res or save power if possible */
>>   static void valleyview_set_cdclk(struct drm_device *dev, int cdclk)
>>   {
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index 0598932..ec10e6a 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -1152,6 +1152,7 @@ void broxton_ddi_phy_uninit(struct drm_device *dev);
>>   void bxt_enable_dc9(struct drm_i915_private *dev_priv);
>>   void bxt_disable_dc9(struct drm_i915_private *dev_priv);
>>   void skl_init_cdclk(struct drm_i915_private *dev_priv);
>> +int skl_sanitize_cdclk(struct drm_i915_private *dev_priv);
>>   void skl_uninit_cdclk(struct drm_i915_private *dev_priv);
>>   void intel_dp_get_m_n(struct intel_crtc *crtc,
>>   		      struct intel_crtc_state *pipe_config);
>> --
>> 2.4.3
>
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