[PATCH v3 2/3] drm/i915/bios: Add function to check if edp data override is needed

[Kandpal, Suraj]

> Subject: Re: [PATCH v3 2/3] drm/i915/bios: Add function to check if edp data
> override is needed
> 
> 
> On 7/31/2025 10:46 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]
> >
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >   drivers/gpu/drm/i915/display/intel_bios.c | 29 +++++++++++++++++++++++
> >   drivers/gpu/drm/i915/display/intel_bios.h |  2 ++
> >   2 files changed, 31 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c
> > b/drivers/gpu/drm/i915/display/intel_bios.c
> > index 8337ebe0f2c8..7adb7c4b0432 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
> > +2518,16 @@ 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_supports_edp_rate(const struct
> intel_bios_encoder_data *devdata,
> > +				     int rate)
> > +{
> > +	if (!devdata || devdata->display->vbt.version < 263)
> > +		return false;
> > +
> > +	return devdata->child.edp_data_rate_override &
> > +edp_rate_override_mask(rate);
> 
> 
> The function name intel_bios_encoder_supports_edp_rate() suggests that it
> returns true if a given eDP rate is supported.
> However, the current implementation returns true when the corresponding bit
> is set in edp_data_rate_override, which actually indicates that the rate is
> rejected.
> 
> To avoid confusion, either the function should be renamed to
> intel_bios_encoder_rejects_edp_rate()
> to reflect its actual behavior, or the logic should be inverted so that the
> function returns true only when the rate is acceptable.
> 

Sure will change function name

Regards,
Suraj Kandpal

> Regards,
> 
> Ankit
> 
> > +}
> > +
> >   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..a4abaa89a682 100644
> > --- a/drivers/gpu/drm/i915/display/intel_bios.h
> > +++ b/drivers/gpu/drm/i915/display/intel_bios.h
> > @@ -251,6 +251,8 @@ bool intel_bios_encoder_supports_dvi(const struct
> intel_bios_encoder_data *devda
> >   bool intel_bios_encoder_supports_hdmi(const struct
> intel_bios_encoder_data *devdata);
> >   bool intel_bios_encoder_supports_dp(const struct intel_bios_encoder_data
> *devdata);
> >   bool intel_bios_encoder_supports_edp(const struct
> > intel_bios_encoder_data *devdata);
> > +bool intel_bios_encoder_supports_edp_rate(const struct
> intel_bios_encoder_data *devdata,
> > +					  int rate);
> >   bool intel_bios_encoder_supports_typec_usb(const struct
> intel_bios_encoder_data *devdata);
> >   bool intel_bios_encoder_supports_tbt(const struct intel_bios_encoder_data
> *devdata);
> >   bool intel_bios_encoder_supports_dsi(const struct
> > intel_bios_encoder_data *devdata);