Re: [RFC PATCH] drm/i915: Consider SPLL as another shared pll.

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Sep 16, 2015 at 09:23:59AM +0200, Maarten Lankhorst wrote:
> When diagnosing a unrelated bug for someone on irc, it would seem the hardware can
> be brought up by the BIOS with the embedded displayport using the SPLL for spread spectrum.
> 
> Right now this is not handled well in i915, and it calculates the crtc needs to
> be reprogrammed on the first modeset without SSC, but  the SPLL itself was kept
> active. Fix this by exposing SPLL as a shared pll that will not be returned
> by intel_get_shared_dpll; you have to know it exists to use it. ;-)
> 
> Cc: Emil Renner Berthing <kernel@esmil.dk>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
> RFC because I haven't tested it with VGA, but it seems to work according to fix
> the problem mentioned above.
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 81adf89b92f1..cacdac67d9ba 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -345,6 +345,8 @@ enum intel_dpll_id {
>  	/* hsw/bdw */
>  	DPLL_ID_WRPLL1 = 0,
>  	DPLL_ID_WRPLL2 = 1,
> +	DPLL_ID_SPLL = 2,
> +
>  	/* skl */
>  	DPLL_ID_SKL_DPLL1 = 0,
>  	DPLL_ID_SKL_DPLL2 = 1,
> diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
> index af5e43bef4a4..592d8fe9f991 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -138,18 +138,6 @@ static void hsw_crt_get_config(struct intel_encoder *encoder,
>  	pipe_config->base.adjusted_mode.flags |= intel_crt_get_flags(encoder);
>  }
>  
> -static void hsw_crt_pre_enable(struct intel_encoder *encoder)
> -{
> -	struct drm_device *dev = encoder->base.dev;
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -
> -	WARN(I915_READ(SPLL_CTL) & SPLL_PLL_ENABLE, "SPLL already enabled\n");
> -	I915_WRITE(SPLL_CTL,
> -		   SPLL_PLL_ENABLE | SPLL_PLL_FREQ_1350MHz | SPLL_PLL_SSC);
> -	POSTING_READ(SPLL_CTL);
> -	udelay(20);
> -}
> -
>  /* Note: The caller is required to filter out dpms modes not supported by the
>   * platform. */
>  static void intel_crt_set_dpms(struct intel_encoder *encoder, int mode)
> @@ -216,19 +204,6 @@ static void pch_post_disable_crt(struct intel_encoder *encoder)
>  	intel_disable_crt(encoder);
>  }
>  
> -static void hsw_crt_post_disable(struct intel_encoder *encoder)
> -{
> -	struct drm_device *dev = encoder->base.dev;
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -	uint32_t val;
> -
> -	DRM_DEBUG_KMS("Disabling SPLL\n");
> -	val = I915_READ(SPLL_CTL);
> -	WARN_ON(!(val & SPLL_PLL_ENABLE));
> -	I915_WRITE(SPLL_CTL, val & ~SPLL_PLL_ENABLE);
> -	POSTING_READ(SPLL_CTL);
> -}
> -
>  static void intel_enable_crt(struct intel_encoder *encoder)
>  {
>  	struct intel_crt *crt = intel_encoder_to_crt(encoder);
> @@ -280,6 +255,8 @@ static bool intel_crt_compute_config(struct intel_encoder *encoder,
>  	if (HAS_DDI(dev)) {
>  		pipe_config->ddi_pll_sel = PORT_CLK_SEL_SPLL;
>  		pipe_config->port_clock = 135000 * 2;
> +		pipe_config->dpll_hw_state.wrpll =
> +			SPLL_PLL_ENABLE | SPLL_PLL_FREQ_1350MHz | SPLL_PLL_SSC;
>  	}
>  
>  	return true;
> @@ -861,8 +838,6 @@ void intel_crt_init(struct drm_device *dev)
>  	if (HAS_DDI(dev)) {
>  		crt->base.get_config = hsw_crt_get_config;
>  		crt->base.get_hw_state = intel_ddi_get_hw_state;
> -		crt->base.pre_enable = hsw_crt_pre_enable;
> -		crt->base.post_disable = hsw_crt_post_disable;
>  	} else {
>  		crt->base.get_config = intel_crt_get_config;
>  		crt->base.get_hw_state = intel_crt_get_hw_state;
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index 61575f67a626..dabd903147fa 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1269,6 +1269,18 @@ hsw_ddi_pll_select(struct intel_crtc *intel_crtc,
>  		}
>  
>  		crtc_state->ddi_pll_sel = PORT_CLK_SEL_WRPLL(pll->id);
> +	} else if (crtc_state->ddi_pll_sel == PORT_CLK_SEL_SPLL) {
> +		struct drm_atomic_state *state = crtc_state->base.state;
> +		struct intel_shared_dpll_config *spll =
> +			&intel_atomic_get_shared_dpll_state(state)[DPLL_ID_SPLL];
> +
> +		if (spll->crtc_mask &&
> +		    WARN_ON(spll->hw_state.wrpll != crtc_state->dpll_hw_state.wrpll))
> +			return false;
> +
> +		crtc_state->shared_dpll = DPLL_ID_SPLL;
> +		spll->hw_state.wrpll = crtc_state->dpll_hw_state.wrpll;
> +		spll->crtc_mask |= 1 << intel_crtc->pipe;
>  	}
>  
>  	return true;
> @@ -2414,19 +2426,31 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder)
>  static void hsw_ddi_pll_enable(struct drm_i915_private *dev_priv,
>  			       struct intel_shared_dpll *pll)
>  {
> -	I915_WRITE(WRPLL_CTL(pll->id), pll->config.hw_state.wrpll);
> -	POSTING_READ(WRPLL_CTL(pll->id));
> +	uint32_t reg;
> +
> +	if (pll->id == DPLL_ID_SPLL)
> +		reg = SPLL_CTL;
> +	else
> +		reg = WRPLL_CTL(pll->id);

This is a bit ugly, and reusing hw_sate.wrpll is also a bit fragile due to
the overlaps. I think it'd be better to add hw_state.spll (including hw
state cross-checking) and specialising the enable/disable/get_hw_state
functions.

With that this is Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> +
> +	I915_WRITE(reg, pll->config.hw_state.wrpll);
> +	POSTING_READ(reg);
>  	udelay(20);
>  }
>  
>  static void hsw_ddi_pll_disable(struct drm_i915_private *dev_priv,
>  				struct intel_shared_dpll *pll)
>  {
> -	uint32_t val;
> +	uint32_t reg, val;
>  
> -	val = I915_READ(WRPLL_CTL(pll->id));
> -	I915_WRITE(WRPLL_CTL(pll->id), val & ~WRPLL_PLL_ENABLE);
> -	POSTING_READ(WRPLL_CTL(pll->id));
> +	if (pll->id == DPLL_ID_SPLL)
> +		reg = SPLL_CTL;
> +	else
> +		reg = WRPLL_CTL(pll->id);
> +
> +	val = I915_READ(reg);
> +	I915_WRITE(reg, val & ~WRPLL_PLL_ENABLE);
> +	POSTING_READ(reg);
>  }
>  
>  static bool hsw_ddi_pll_get_hw_state(struct drm_i915_private *dev_priv,
> @@ -2438,23 +2462,28 @@ static bool hsw_ddi_pll_get_hw_state(struct drm_i915_private *dev_priv,
>  	if (!intel_display_power_is_enabled(dev_priv, POWER_DOMAIN_PLLS))
>  		return false;
>  
> -	val = I915_READ(WRPLL_CTL(pll->id));
> -	hw_state->wrpll = val;
> +	if (pll->id == DPLL_ID_SPLL)
> +		val = I915_READ(SPLL_CTL);
> +	else
> +		val = I915_READ(WRPLL_CTL(pll->id));
>  
> +	hw_state->wrpll = val;
>  	return val & WRPLL_PLL_ENABLE;
>  }
>  
>  static const char * const hsw_ddi_pll_names[] = {
>  	"WRPLL 1",
>  	"WRPLL 2",
> +	"SPLL"
>  };
>  
>  static void hsw_shared_dplls_init(struct drm_i915_private *dev_priv)
>  {
>  	int i;
>  
> -	dev_priv->num_shared_dpll = 2;
> +	dev_priv->num_shared_dpll = 3;
>  
> +	/* SPLL is special, but needs to be initialized anyway.. */
>  	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
>  		dev_priv->shared_dplls[i].id = i;
>  		dev_priv->shared_dplls[i].name = hsw_ddi_pll_names[i];
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index ca9278be49f7..582360d2fa08 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4208,6 +4208,7 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc,
>  	struct intel_shared_dpll *pll;
>  	struct intel_shared_dpll_config *shared_dpll;
>  	enum intel_dpll_id i;
> +	int max = dev_priv->num_shared_dpll;
>  
>  	shared_dpll = intel_atomic_get_shared_dpll_state(crtc_state->base.state);
>  
> @@ -4242,9 +4243,11 @@ struct intel_shared_dpll *intel_get_shared_dpll(struct intel_crtc *crtc,
>  		WARN_ON(shared_dpll[i].crtc_mask);
>  
>  		goto found;
> -	}
> +	} else if (INTEL_INFO(dev_priv)->gen < 9 && HAS_DDI(dev_priv))
> +		/* Do not consider SPLL */
> +		max = 2;
>  
> -	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
> +	for (i = 0; i < max; i++) {
>  		pll = &dev_priv->shared_dplls[i];
>  
>  		/* Only want to check enabled timings first */
> @@ -9696,6 +9699,8 @@ static void haswell_get_ddi_pll(struct drm_i915_private *dev_priv,
>  	case PORT_CLK_SEL_WRPLL2:
>  		pipe_config->shared_dpll = DPLL_ID_WRPLL2;
>  		break;
> +	case PORT_CLK_SEL_SPLL:
> +		pipe_config->shared_dpll = DPLL_ID_SPLL;
>  	}
>  }
>  
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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