Re: [Intel-gfx] [PATCH 6/9] drm/i915/display: description-based initialization for remaining ddi platforms

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 23 Dec 2019, Lucas De Marchi <lucas.demarchi@intel.com> wrote:
> Support remaining platforms under HAS_DDI() by providing a slightly more
> complex is_port_present() hook. The downside is that now we call
> I915_READ(SFUSE_STRAP) for each port being initialized, but that's only
> on initialization: a few more mmio reads won't hurt.
>
> Alternatives would be to provide one hook per port, or to have a
> "pre_init()" hook that takes care of the mmio read. However I think this
> is simpler - we may need to adapt if future platforms don't follow the
> same initialization "template".

All of this really makes me wonder if we end up being *more* complicated
overall by trying very hard to make this generic, when, in reality, it
doesn't seem to be all that generic.

As I said, two relatively low hanging improvements would be a) moving
VBT specific hacks to intel_bios.c and b) adding port mask to
intel_device_info. Those two alone would go a long way in simplifying
intel_setup_outputs().

>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 72 +++++++++++++-------
>  1 file changed, 46 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 6b4d320ff92c..ad85cf75c815 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -16246,6 +16246,34 @@ static bool icl_is_port_present(struct drm_i915_private *i915,
>  		intel_bios_is_port_present(i915, PORT_F);
>  }
>  
> +static bool ddi_is_port_present(struct drm_i915_private *i915,
> +				const struct intel_ddi_port_info *port_info)
> +{
> +	/* keep I915_READ() happy */

Display could get rid of I915_READ and I915_WRITE after
https://patchwork.freedesktop.org/series/70298/ ...

BR,
Jani.

> +	struct drm_i915_private *dev_priv = i915;
> +
> +	if (port_info->port == PORT_A)
> +		return I915_READ(DDI_BUF_CTL(PORT_A))
> +			& DDI_INIT_DISPLAY_DETECTED;
> +
> +	if (port_info->port == PORT_E)
> +		return IS_GEN9_BC(dev_priv) &&
> +			intel_bios_is_port_present(i915, PORT_E);
> +
> +	switch (port_info->port) {
> +	case PORT_B:
> +		return I915_READ(SFUSE_STRAP) & SFUSE_STRAP_DDIB_DETECTED;
> +	case PORT_C:
> +		return I915_READ(SFUSE_STRAP) & SFUSE_STRAP_DDIC_DETECTED;
> +	case PORT_D:
> +		return I915_READ(SFUSE_STRAP) & SFUSE_STRAP_DDID_DETECTED;
> +	case PORT_F:
> +		return I915_READ(SFUSE_STRAP) & SFUSE_STRAP_DDIF_DETECTED;
> +	default:
> +		return false;
> +	}
> +}
> +
>  static const struct intel_output tgl_output = {
>  	.dsi_init = icl_dsi_init,
>  	.ddi_ports = {
> @@ -16296,11 +16324,24 @@ static const struct intel_output gen9lp_output = {
>  	},
>  };
>  
> +static const struct intel_output ddi_output = {
> +	.is_port_present = ddi_is_port_present,
> +	.ddi_ports = {
> +		{ .port = PORT_A },
> +		{ .port = PORT_B },
> +		{ .port = PORT_C },
> +		{ .port = PORT_D },
> +		{ .port = PORT_E },
> +		{ .port = PORT_F },
> +		{ .port = PORT_NONE }
> +	}
> +};
> +
>  /*
>   * Use a description-based approach for platforms that can be supported with a
>   * static table
>   */
> -static void setup_ddi_outputs_desc(struct drm_i915_private *i915)
> +static void setup_ddi_outputs(struct drm_i915_private *i915)
>  {
>  	const struct intel_output *output;
>  	const struct intel_ddi_port_info *port_info;
> @@ -16313,6 +16354,8 @@ static void setup_ddi_outputs_desc(struct drm_i915_private *i915)
>  		output = &icl_output;
>  	else if (IS_GEN9_LP(i915))
>  		output = &gen9lp_output;
> +	else
> +		output = &ddi_output;
>  
>  	for (port_info = output->ddi_ports;
>  	     port_info->port != PORT_NONE; port_info++) {
> @@ -16338,35 +16381,12 @@ static void intel_setup_outputs(struct drm_i915_private *dev_priv)
>  		return;
>  
>  	if (INTEL_GEN(dev_priv) >= 11 || IS_GEN9_LP(dev_priv)) {
> -		setup_ddi_outputs_desc(dev_priv);
> +		setup_ddi_outputs(dev_priv);
>  	} else if (HAS_DDI(dev_priv)) {
> -		int found;
> -
>  		if (intel_ddi_crt_present(dev_priv))
>  			intel_crt_init(dev_priv);
>  
> -		found = I915_READ(DDI_BUF_CTL(PORT_A)) & DDI_INIT_DISPLAY_DETECTED;
> -		if (found)
> -			intel_ddi_init(dev_priv, PORT_A);
> -
> -		/* DDI B, C, D, and F detection is indicated by the SFUSE_STRAP
> -		 * register */
> -		found = I915_READ(SFUSE_STRAP);
> -
> -		if (found & SFUSE_STRAP_DDIB_DETECTED)
> -			intel_ddi_init(dev_priv, PORT_B);
> -		if (found & SFUSE_STRAP_DDIC_DETECTED)
> -			intel_ddi_init(dev_priv, PORT_C);
> -		if (found & SFUSE_STRAP_DDID_DETECTED)
> -			intel_ddi_init(dev_priv, PORT_D);
> -		if (found & SFUSE_STRAP_DDIF_DETECTED)
> -			intel_ddi_init(dev_priv, PORT_F);
> -		/*
> -		 * On SKL we don't have a way to detect DDI-E so we rely on VBT.
> -		 */
> -		if (IS_GEN9_BC(dev_priv) &&
> -		    intel_bios_is_port_present(dev_priv, PORT_E))
> -			intel_ddi_init(dev_priv, PORT_E);
> +		setup_ddi_outputs(dev_priv);
>  	} else if (HAS_PCH_SPLIT(dev_priv)) {
>  		int found;

-- 
Jani Nikula, Intel Open Source Graphics Center
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