Re: [PATCH] drm/i915/dp: Enable DSC on external DP display if VBT allows

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

On Tue, May 27, 2025 at 07:59:06AM +0000, Lee Shawn C wrote:
> A DSC setting has been available in VBT since version 251, which allows
> users to enable or disable the DSC feature based on their system design.
> With this in mind, DP driver should reference this setting and avoid
> enabling DSC if this value is not allowed.
> 
> Cc: Shankar Uma <uma.shankar@intel.com>
> Cc: Jani Nikula <jani.nikula@linux.intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Lee Shawn C <shawn.c.lee@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_bios.c   |  8 ++++++++
>  drivers/gpu/drm/i915/display/intel_bios.h   |  1 +
>  drivers/gpu/drm/i915/display/intel_dp.c     | 12 +++++++++---
>  drivers/gpu/drm/i915/display/intel_dp.h     |  2 +-
>  drivers/gpu/drm/i915/display/intel_dp_mst.c |  2 +-
>  5 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index ba7b8938b17c..f08dd54fe4d4 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -3548,6 +3548,14 @@ bool intel_bios_get_dsc_params(struct intel_encoder *encoder,
>  	return false;
>  }
>  
> +bool intel_bios_encoder_ext_display_dsc_disabled(const struct intel_bios_encoder_data *devdata)
> +{
> +	if (!devdata || devdata->display->vbt.version < 251)
> +		return false;
> +
> +	return devdata->child.disable_compression_for_ext_disp;

Windows doesn't actually use that bit, so we probably shouldn't either.

-- 
Ville Syrjälä
Intel