[Intel-gfx] [PATCH 03/29] drm/i915: Replace the aux ddc name switch statement with a table

[Chris Wilson]

On Wed, Nov 04, 2015 at 11:19:51PM +0200, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 38 +++++++++++++-------------------------
>  1 file changed, 13 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index a26995a..62fb95c 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1095,28 +1095,14 @@ intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>  	enum port port = intel_dig_port->port;
> -	const char *name = NULL;
>  	int ret;
> -
> -	switch (port) {
> -	case PORT_A:
> -		name = "DPDDC-A";
> -		break;
> -	case PORT_B:
> -		name = "DPDDC-B";
> -		break;
> -	case PORT_C:
> -		name = "DPDDC-C";
> -		break;
> -	case PORT_D:
> -		name = "DPDDC-D";
> -		break;
> -	case PORT_E:
> -		name = "DPDDC-E";
> -		break;
> -	default:
> -		BUG();
> -	}
> +	static const char * const ddc_name[] = {
> +		[PORT_A] = "DPDDC-A",
> +		[PORT_B] = "DPDDC-B",
> +		[PORT_C] = "DPDDC-C",
> +		[PORT_D] = "DPDDC-D",
> +		[PORT_E] = "DPDDC-E",
> +	};
>  
>  	if (INTEL_INFO(dev_priv)->gen >= 9)
>  		intel_dp->aux_ch_ctl_reg = skl_aux_ctl_reg(dev_priv, port);
> @@ -1125,17 +1111,18 @@ intel_dp_aux_init(struct intel_dp *intel_dp, struct intel_connector *connector)
>  	else
>  		intel_dp->aux_ch_ctl_reg = g4x_aux_ctl_reg(dev_priv, port);
>  
> -	intel_dp->aux.name = name;
> +	intel_dp->aux.name = ddc_name[port];

What defense do we have against the introduction of PORT_F and somebody
forgetting to check here?

static const char *ddc_name(enum port port) {
	static const char * const names[] = {
		[PORT_A] = "DPDDC-A",
		[PORT_B] = "DPDDC-B",
		[PORT_C] = "DPDDC-C",
		[PORT_D] = "DPDDC-D",
		[PORT_E] = "DPDDC-E",
	};
	if (WARN_ON(port >= ARRAY_SIZE(names))
		return "DPDDC-XXX";
	return names[port];
}
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre