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

[Lee, Shawn C]

On Wed, 28 May 2025, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote
>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 at intel.com>
>> Cc: Jani Nikula <jani.nikula at linux.intel.com>
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Signed-off-by: Lee Shawn C <shawn.c.lee at 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.

Thanks for your comments, Ville!

Just my two cents, this bit has already reserved in VBT. And customer wants to use it as part of their system design.
Would it be possible for you to consider implementing this to support the requirement?

Best regards,
Shawn

>
>--
>Ville Syrjälä
>Intel