[Intel-gfx] [PATCH 11/12] drm/i915: WARN if a port should use VBT provided vswing tables

[Rodrigo Vivi]

On Fri, Jul 15, 2022 at 11:20:43PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> We don't parse the VBT vswing/preemphassis tables at all currently.
> Let's WARN if a port wants to use them so we get a heads up that
> whether we really need to implement this stuff or not. My
> current stash contains no VBTs with this bit set.

let's unlock a new can of worms?! :)

I believe this deserves a /* XXX: comment with the code in case
someone else finds this warns first and doesn't use the git blame

anyways
Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_bios.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 51dde5bfd956..cd86b65055ef 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -2661,6 +2661,10 @@ static void parse_ddi_port(struct intel_bios_encoder_data *devdata)
>  		return;
>  	}
>  
> +	drm_WARN(&i915->drm, child->use_vbt_vswing,
> +		 "Port %c asks to use VBT vswing/preemph tables\n",
> +		 port_name(port));
> +
>  	if (i915->vbt.ports[port]) {
>  		drm_dbg_kms(&i915->drm,
>  			    "More than one child device for port %c in VBT, using the first.\n",
> -- 
> 2.35.1
>