Re: [PATCH v3 2/2] drm/i915: vlv: W/a for hotplug/manual VGA detection

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

On Thu, Jan 09, 2014 at 05:08:16PM +0200, Imre Deak wrote:
> VGA detection requires the reference clock to be on, so make sure this
> is the case.
> 
> This fixes VGA hotplug/manual detection where all pipes are off and so
> we would normally disable all clocks.
> 
> v2:
> - Instead of disabling PSR clock gating, force the reference clock on
>   through the DPLL_A register. (Kin Chan S <kin.s.chan@intel.com>)
> 
> v3:
> - Move enabling of the clock to intel_reset_dpio() and use the DPLL_B
>   register instead, where we already have a similar tweak for the CRI
>   clock. (Ville)
> 
> Reported-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

For the series:

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 3262ac4..4e2598b 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1377,8 +1377,12 @@ static void intel_reset_dpio(struct drm_device *dev)
>  	if (!IS_VALLEYVIEW(dev))
>  		return;
>  
> -	/* Enable the CRI clock source so we can get at the display */
> +	/*
> +	 * Enable the CRI clock source so we can get at the display and the
> +	 * reference clock for VGA hotplug / manual detection.
> +	 */
>  	I915_WRITE(DPLL(PIPE_B), I915_READ(DPLL(PIPE_B)) |
> +		   DPLL_REFA_CLK_ENABLE_VLV |
>  		   DPLL_INTEGRATED_CRI_CLK_VLV);
>  
>  	/*
> @@ -1507,9 +1511,12 @@ static void vlv_disable_pll(struct drm_i915_private *dev_priv, enum pipe pipe)
>  	/* Make sure the pipe isn't still relying on us */
>  	assert_pipe_disabled(dev_priv, pipe);
>  
> -	/* Leave integrated clock source enabled */
> +	/*
> +	 * Leave integrated clock source and reference clock enabled for pipe B.
> +	 * The latter is needed for VGA hotplug / manual detection.
> +	 */
>  	if (pipe == PIPE_B)
> -		val = DPLL_INTEGRATED_CRI_CLK_VLV;
> +		val = DPLL_INTEGRATED_CRI_CLK_VLV | DPLL_REFA_CLK_ENABLE_VLV;
>  	I915_WRITE(DPLL(pipe), val);
>  	POSTING_READ(DPLL(pipe));
>  }
> @@ -4986,7 +4993,11 @@ static void vlv_update_pll(struct intel_crtc *crtc)
>  
>  	vlv_dpio_write(dev_priv, pipe, VLV_PLL_DW11(pipe), 0x87871000);
>  
> -	/* Enable DPIO clock input */
> +	/*
> +	 * Enable DPIO clock input. We should never disable the reference
> +	 * clock for pipe B, since VGA hotplug / manual detection depends
> +	 * on it.
> +	 */
>  	dpll = DPLL_EXT_BUFFER_ENABLE_VLV | DPLL_REFA_CLK_ENABLE_VLV |
>  		DPLL_VGA_MODE_DIS | DPLL_INTEGRATED_CLOCK_VLV;
>  	/* We should never disable this, set it here for state tracking */
> -- 
> 1.8.4

-- 
Ville Syrjälä
Intel OTC