[Intel-gfx] [PATCH 32/67] drm/i915/cnl: DDI - PLL mapping

[Ville Syrjälä]

On Thu, May 04, 2017 at 03:02:07PM +0200, Maarten Lankhorst wrote:
> Op 04-05-17 om 14:44 schreef Ville Syrjälä:
> > On Thu, May 04, 2017 at 03:35:51PM +0300, Ander Conselvan De Oliveira wrote:
> >> On Fri, 2017-04-07 at 18:12 -0300, Paulo Zanoni wrote:
> >>> Em Qui, 2017-04-06 às 12:15 -0700, Rodrigo Vivi escreveu:
> >>>> One of the steps for PLL (un)initialization is to (un)map
> >>>> the correspondent DDI that is actually using that PLL.
> >>>>
> >>>> So, let's do this step following the places already stablished
> >>>> and used so far, although spec put this as part of PLL
> >>>> initialization sequences.
> >>>>
> >>>> v2: Use proper prefix on bits names as suggested by Ander.
> >>>> v3: Add missed "~". Without that the logic was inverted
> >>>>     so we were disabling interrupts.
> >>>>     Credits-to: Clinton
> >>>>     Credits-to: Art
> >>>> v4: Spec is getting updated to do DDI -> PLL mapping
> >>>>     and clock on in 2 separated reg writes. (Paulo)
> >>>>     Also update bits definitions to use space
> >>>>     (1 << 1) instead of (1<<1). (Paulo)
> >>>>
> >>>> Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
> >>>> Cc: Art Runyan <arthur.j.runyan at intel.com>
> >>>> Cc: Clint Taylor <clinton.a.taylor at intel.com>
> >>>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >>>> Cc: Kahola, Mika <mika.kahola at intel.com>
> >>>> Cc: Ander Conselvan De Oliveira <ander.conselvan.de.oliveira at intel.co
> >>>> m>
> >>>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> >>>> Reviewed-by: Kahola, Mika <mika.kahola at intel.com>
> >>>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> >>>> ---
> >>>>  drivers/gpu/drm/i915/i915_reg.h  |  9 +++++++++
> >>>>  drivers/gpu/drm/i915/intel_ddi.c | 23 ++++++++++++++++++++---
> >>>>  2 files changed, 29 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> >>>> b/drivers/gpu/drm/i915/i915_reg.h
> >>>> index 3cfc65f..dcb8e21 100644
> >>>> --- a/drivers/gpu/drm/i915/i915_reg.h
> >>>> +++ b/drivers/gpu/drm/i915/i915_reg.h
> >>>> @@ -8150,6 +8150,15 @@ enum {
> >>>>  #define DPLL_CFGCR1(id)	_MMIO_PIPE((id) - SKL_DPLL1,
> >>>> _DPLL1_CFGCR1, _DPLL2_CFGCR1)
> >>>>  #define DPLL_CFGCR2(id)	_MMIO_PIPE((id) - SKL_DPLL1,
> >>>> _DPLL1_CFGCR2, _DPLL2_CFGCR2)
> >>>>  
> >>>> +/*
> >>>> + * CNL Clocks
> >>>> + */
> >>>> +#define DPCLKA_CFGCR0				_MMIO(0x6C200)
> >>>> +#define  DPCLKA_CFGCR0_DDI_CLK_OFF(port)	(1 << ((port)+10))
> >>>> +#define  DPCLKA_CFGCR0_DDI_CLK_SEL_MASK(port)	(3 <<
> >>>> ((port)*2))
> >>>> +#define  DPCLKA_CFGCR0_DDI_CLK_SEL_SHIFT(port)	((port)*2)
> >>>> +#define  DPCLKA_CFGCR0_DDI_CLK_SEL(pll, port)	((pll) <<
> >>>> ((port)*2))
> >>>> +
> >>>>  /* BXT display engine PLL */
> >>>>  #define BXT_DE_PLL_CTL			_MMIO(0x6d000)
> >>>>  #define   BXT_DE_PLL_RATIO(x)		(x)	/*
> >>>> {60,65,100} * 19.2MHz */
> >>>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> >>>> b/drivers/gpu/drm/i915/intel_ddi.c
> >>>> index 0914ad9..2a901bf 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_ddi.c
> >>>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> >>>> @@ -1621,13 +1621,27 @@ static void intel_ddi_clk_select(struct
> >>>> intel_encoder *encoder,
> >>>>  {
> >>>>  	struct drm_i915_private *dev_priv = to_i915(encoder-
> >>>>> base.dev);
> >>>>  	enum port port = intel_ddi_get_encoder_port(encoder);
> >>>> +	uint32_t val;
> >>>>  
> >>>>  	if (WARN_ON(!pll))
> >>>>  		return;
> >>>>  
> >>>> -	if (IS_GEN9_BC(dev_priv)) {
> >>>> -		uint32_t val;
> >>>> +	if (IS_CANNONLAKE(dev_priv)) {
> >>>> +		/* Configure DPCLKA_CFGCR0 to map the DPLL to the
> >>>> DDI. */
> >>>> +		val = I915_READ(DPCLKA_CFGCR0);
> >>>> +		val |= DPCLKA_CFGCR0_DDI_CLK_SEL(pll->id, port);
> >>>> +		I915_WRITE(DPCLKA_CFGCR0, val);
> >>> A question to the Atomic Lords: don't we need some sort of locking
> >>> around this register since it's used by all ports/clocks? I suppose
> >>> dev_priv->dpll_lock would do...
> >>>
> >>> Maybe the same would apply for gen9_bc.
> >> If there are modesets happening in parallel for different crtcs, then some
> >> locking is needed. dpll_lock seems like the right call, that's what's used to
> >> avoid the same problem with the enable/disable hooks.
> > If something is allowing modesets to commit in parallel then probably
> > the whole world is on fire. Historically connection_mutex has been there
> > to protect us, but not sure how that goes with nonblocking commits. I
> > do hope there's still something there to prevents this...
> 
> During nonblocking modesets we don't hold any locks. It's still possible
> that we force serialization through some other means, for example grabbing
> all crtc_states might force serialization previously. But I'm not sure this
> is guaranteed to happen even for SKL. It might happen for when DDB
> allocation or cdclk changes but there's no guarantee during modeset.
> 
> So quite likely you'll need locking here. :)

Someone just need to fix things so that modesets are always serialized.
I don't think anyone has actually reviewd the entire driver sufficiently
to allow parallel modesets.

-- 
Ville Syrjälä
Intel OTC