[PATCH v6 2/3] drm/i915/bios: Add function to check if edp data override is needed

[Nautiyal, Ankit K]

On 8/21/2025 9:56 AM, Suraj Kandpal wrote:
> Add a function that helps identify if the rate provided needs to
> be overridden. For this we need a function that compares the rate
> provided and bitmask of rates provided in VBT.
>
> --v2
> -Rename functions [Jani]
> -Return the mask instead of parsing it in function [Jani]
> -Move the declaration in header [Jani]
>
> --v3
> -Change function name to depict what the function does [Ankit]
>
> --v4
> -Lets not use hweight [Ankit]
>
> Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>


> ---
>   drivers/gpu/drm/i915/display/intel_bios.c | 32 +++++++++++++++++++++++
>   drivers/gpu/drm/i915/display/intel_bios.h |  2 ++
>   2 files changed, 34 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 8337ebe0f2c8..193c7911953e 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -2480,6 +2480,25 @@ static int parse_bdb_216_dp_max_link_rate(const int vbt_max_link_rate)
>   	}
>   }
>   
> +static u32 edp_rate_override_mask(int rate)
> +{
> +	switch (rate) {
> +	case 2000000: return BDB_263_VBT_EDP_LINK_RATE_20;
> +	case 1350000: return BDB_263_VBT_EDP_LINK_RATE_13_5;
> +	case 1000000: return BDB_263_VBT_EDP_LINK_RATE_10;
> +	case 810000: return BDB_263_VBT_EDP_LINK_RATE_8_1;
> +	case 675000: return BDB_263_VBT_EDP_LINK_RATE_6_75;
> +	case 540000: return BDB_263_VBT_EDP_LINK_RATE_5_4;
> +	case 432000: return BDB_263_VBT_EDP_LINK_RATE_4_32;
> +	case 324000: return BDB_263_VBT_EDP_LINK_RATE_3_24;
> +	case 270000: return BDB_263_VBT_EDP_LINK_RATE_2_7;
> +	case 243000: return BDB_263_VBT_EDP_LINK_RATE_2_43;
> +	case 216000: return BDB_263_VBT_EDP_LINK_RATE_2_16;
> +	case 162000: return BDB_263_VBT_EDP_LINK_RATE_1_62;
> +	default: return 0;
> +	}
> +}
> +
>   int intel_bios_dp_max_link_rate(const struct intel_bios_encoder_data *devdata)
>   {
>   	if (!devdata || devdata->display->vbt.version < 216)
> @@ -2499,6 +2518,19 @@ int intel_bios_dp_max_lane_count(const struct intel_bios_encoder_data *devdata)
>   	return devdata->child.dp_max_lane_count + 1;
>   }
>   
> +bool
> +intel_bios_encoder_reject_edp_rate(const struct intel_bios_encoder_data *devdata,
> +				   int rate)
> +{
> +	if (!devdata || devdata->display->vbt.version < 263)
> +		return false;
> +
> +	if (devdata->child.edp_data_rate_override == BDB_263_VBT_EDP_RATES_MASK)
> +		return false;
> +
> +	return devdata->child.edp_data_rate_override & edp_rate_override_mask(rate);
> +}
> +
>   static void sanitize_device_type(struct intel_bios_encoder_data *devdata,
>   				 enum port port)
>   {
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.h b/drivers/gpu/drm/i915/display/intel_bios.h
> index 6cd7a011b8c4..781e08f7eeb2 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.h
> +++ b/drivers/gpu/drm/i915/display/intel_bios.h
> @@ -259,6 +259,8 @@ bool intel_bios_encoder_is_lspcon(const struct intel_bios_encoder_data *devdata)
>   bool intel_bios_encoder_lane_reversal(const struct intel_bios_encoder_data *devdata);
>   bool intel_bios_encoder_hpd_invert(const struct intel_bios_encoder_data *devdata);
>   enum port intel_bios_encoder_port(const struct intel_bios_encoder_data *devdata);
> +bool intel_bios_encoder_reject_edp_rate(const struct intel_bios_encoder_data *devdata,
> +					int rate);
>   enum aux_ch intel_bios_dp_aux_ch(const struct intel_bios_encoder_data *devdata);
>   int intel_bios_dp_boost_level(const struct intel_bios_encoder_data *devdata);
>   int intel_bios_dp_max_lane_count(const struct intel_bios_encoder_data *devdata);