Re: [Intel-gfx] [PATCH] i915: Set ddi_pll_sel in DP MST path

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

On Mon, Aug 31, 2015 at 11:23:28AM +0300, Ander Conselvan de Oliveira wrote:
> The DP MST encoder config function never sets ddi_pll_sel, even though
> its value is programmed in its ->pre_enable() hook. That used to work
> because a new pipe_config was kzalloc'ed at every modeset, and the value
> of zero selects the highest clock for the PLL. Starting with the commit
> below, the value of ddi_pll_sel is preserved through modesets, and since
> the correct value wasn't properly setup by the MST code, it could lead
> to warnings and blank screens.

The ddi pll handling is still quite a mess. Every platform does things
just a bit different to the next guy.

But yeah, looks like HSW/BDW handle the PLL selection for DP from
the encoder .compute_config() so MST should do the same since it
(re)computes the main link config for each stream. And SKL and BXT
handle DP via the .crtc_compute_clock() path, so nothing needed for
them I suppose.

Reviewed-by: Ville Syrj�l� <ville.syrjala@linux.intel.com>

> 
> commit 8504c74c7ae48b4b8ed1f1c0acf67482a7f45c93
> Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> Date:   Fri May 15 11:51:50 2015 +0300
> 
>     drm/i915: Preserve ddi_pll_sel when allocating new pipe_config
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91628
> Cc: stable@vger.kernel.org
> Cc: Timo Aaltonen <tjaalton@ubuntu.com>
> Cc: Luciano Coelho <luciano.coelho@intel.com>
> Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c     | 2 +-
>  drivers/gpu/drm/i915/intel_dp_mst.c | 5 +++++
>  drivers/gpu/drm/i915/intel_drv.h    | 1 +
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 9e90a2b..393aed0 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1190,7 +1190,7 @@ skl_edp_set_pll_config(struct intel_crtc_state *pipe_config)
>  	pipe_config->dpll_hw_state.ctrl1 = ctrl1;
>  }
>  
> -static void
> +void
>  hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config)
>  {
>  	memset(&pipe_config->dpll_hw_state, 0,
> diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> index ebf2054..677d70e 100644
> --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> @@ -33,6 +33,7 @@
>  static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  					struct intel_crtc_state *pipe_config)
>  {
> +	struct drm_device *dev = encoder->base.dev;
>  	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(&encoder->base);
>  	struct intel_digital_port *intel_dig_port = intel_mst->primary;
>  	struct intel_dp *intel_dp = &intel_dig_port->dp;
> @@ -88,6 +89,10 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
>  			       &pipe_config->dp_m_n);
>  
>  	pipe_config->dp_m_n.tu = slots;
> +
> +	if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> +		hsw_dp_set_ddi_pll_sel(pipe_config);
> +
>  	return true;
>  
>  }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index c61ba47..458f56c 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1209,6 +1209,7 @@ void intel_edp_drrs_disable(struct intel_dp *intel_dp);
>  void intel_edp_drrs_invalidate(struct drm_device *dev,
>  		unsigned frontbuffer_bits);
>  void intel_edp_drrs_flush(struct drm_device *dev, unsigned frontbuffer_bits);
> +void hsw_dp_set_ddi_pll_sel(struct intel_crtc_state *pipe_config);
>  
>  /* intel_dp_mst.c */
>  int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
> -- 
> 2.4.3
> 
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-- 
Ville Syrj�l�
Intel OTC