Re: [PATCH] drm/i915/vlv: untangle integrated clock source handling

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Sep 27, 2013 at 12:22:11PM -0700, Jesse Barnes wrote:
> The global integrated clock source bit resides in DPLL B on VLV, but we
> were treating it as a per-pipe resource.  It needs to be set whenever
> any PLL is active,

Actually AFAIU the cri clock has to be running even if we just attempt
to do any register access to the phy.

> so pull setting the bit out of vlv_update_pll and
> into vlv_enable_pll.  Also add a vlv_disable_pll to prevent disabling it
> when pipe B shuts down.
> 
> I'm guessing on the references here, I expect this to bite any config
> where multiple displays are active or displays are moved from pipe to
> pipe.
> 
> References: https://bugs.freedesktop.org/show_bug.cgi?id=67245
> References: https://bugs.freedesktop.org/show_bug.cgi?id=69693
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 0eeba84..def2473 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1386,6 +1386,13 @@ static void vlv_enable_pll(struct intel_crtc *crtc)
>  	if (IS_MOBILE(dev_priv->dev) && !IS_I830(dev_priv->dev))
>  		assert_panel_unlocked(dev_priv, crtc->pipe);
>  
> +	/* Make sure to use the integrated clock source */
> +	if (!crtc->pipe)
> +		I915_WRITE(DPLL(1), I915_READ(DPLL(1)) |
> +			   DPLL_INTEGRATED_CRI_CLK_VLV);

We may need the cri clock before this, so I would just put this part
into some modeset hw init function.

> +	else
> +		dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;

And obviously this part has to stay here, or we could do a 
 'I915_READ(DPLL(1)) & DPLL_INTEGRATED_CRI_CLK_VLV)' to extract the
current setting from the hardware like you do in vlv_disable_pll().
In any case I think doing it the same way for both enable and
disable would be good.

Or we could leave setting of this bit up to vlv_update_pll() like it was
before.

> +
>  	I915_WRITE(reg, dpll);
>  	POSTING_READ(reg);
>  	udelay(150);
> @@ -1476,6 +1483,20 @@ static void i9xx_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
>  	POSTING_READ(DPLL(pipe));
>  }
>  
> +static void vlv_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
> +{
> +	u32 val = 0;
> +
> +	/* Make sure the pipe isn't still relying on us */
> +	assert_pipe_disabled(dev_priv, pipe);
> +
> +	/* Leave integrated clock source enabled for the other pipe */
> +	if (pipe)
> +		val = I915_READ(DPLL(pipe)) & DPLL_INTEGRATED_CRI_CLK_VLV;

Right. As stated we need to either hardcode the bit on (if we assume 1
is the right answer always) or we read it back like you do.

> +	I915_WRITE(DPLL(pipe), val);
> +	POSTING_READ(DPLL(pipe));
> +}
> +
>  void vlv_wait_port_ready(struct drm_i915_private *dev_priv, int port)
>  {
>  	u32 port_mask;
> @@ -3886,7 +3907,9 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
>  		if (encoder->post_disable)
>  			encoder->post_disable(encoder);
>  
> -	if (!intel_pipe_has_type(crtc, INTEL_OUTPUT_DSI))
> +	if (IS_VALLEYVIEW(dev) && !intel_pipe_has_type(crtc, INTEL_OUTPUT_DSI))
> +		vlv_disable_pll(dev_priv, pipe);
> +	else if (!IS_VALLEYVIEW(dev))
>  		i9xx_disable_pll(dev_priv, pipe);
>  
>  	intel_crtc->active = false;
> @@ -4626,8 +4649,6 @@ static void vlv_update_pll(struct intel_crtc *crtc)
>  	/* Enable DPIO clock input */
>  	dpll = DPLL_EXT_BUFFER_ENABLE_VLV | DPLL_REFA_CLK_ENABLE_VLV |
>  		DPLL_VGA_MODE_DIS | DPLL_INTEGRATED_CLOCK_VLV;
> -	if (pipe)
> -		dpll |= DPLL_INTEGRATED_CRI_CLK_VLV;
>  
>  	dpll |= DPLL_VCO_ENABLE;
>  	crtc->config.dpll_hw_state.dpll = dpll;
> -- 
> 1.8.3.1
> 
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-- 
Ville Syrjälä
Intel OTC