Re: [PATCH] drm/i915/cnl: Map VBT DDC Pin to BSpec DDC Pin.

[Jani Nikula <jani.nikula@intel.com>]

On Fri, 20 Oct 2017, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Fri, Oct 20, 2017 at 12:11:29PM +0300, Jani Nikula wrote:
>> On Thu, 19 Oct 2017, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
>> > Starting on CNL we now need to map VBT DDC Pin to
>> > BSPec DDC Pin values. Not a direct translation anymore.
>> >
>> > According to VBT
>> > Block 2 (General Bytes Definition)
>> > DDC Bus
>> >
>> > +----------+-----------+--------------------+
>> > | DDI Type | VBT Value | Bspec Mapped Value |
>> > +----------+-----------+--------------------+
>> > | DDI-B    | 0x1       | 0x1                |
>> > | DDI-C    | 0x2       | 0x2                |
>> > | DDI-D    | 0x3       | 0x4                |
>> > | DDI-F    | 0x4       | 0x3                |
>> > +----------+-----------+--------------------+
>> >
>> > v2: Move defines to a better place.
>> >     This is actually CNL_PCH not CNL only.
>> > v3: Accepting Ville's suggestions: enums and array to
>> >     to make this future proof.
>> >
>> > Cc: Jani Nikula <jani.nikula@intel.com>
>> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
>> > Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
>> > Cc: Clinton Taylor <clinton.a.taylor@intel.com>
>> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/intel_bios.c     | 26 ++++++++++++++++----------
>> >  drivers/gpu/drm/i915/intel_vbt_defs.h | 15 +++++++++++++++
>> >  2 files changed, 31 insertions(+), 10 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
>> > index dc4fad30bf4f..79638308664c 100644
>> > --- a/drivers/gpu/drm/i915/intel_bios.c
>> > +++ b/drivers/gpu/drm/i915/intel_bios.c
>> > @@ -1071,6 +1071,21 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
>> >  	}
>> >  }
>> >  
>> > +static const enum bspec_gmbus_pin cnp_ddc_pin_map[] = {
>> > +	[DDC_BUS_DDI_B] = GMBUS_PIN_1,
>> > +	[DDC_BUS_DDI_C] = GMBUS_PIN_2,
>> > +	[DDC_BUS_DDI_D] = GMBUS_PIN_4,
>> > +	[DDC_BUS_DDI_F] = GMBUS_PIN_3,
>> 
>> I think the two last lines deserve comments like /* sic */ or something.
>> 
>> > +};
>> > +
>> > +static u8 get_ddc_pin(struct drm_i915_private *dev_priv, u8 vbt_pin)
>> 
>> Nitpick, You're passing in a pin and you get a pin? How about
>> "map_ddc_pin"? Like your array name suggests?
>> 
>> > +{
>> > +	if (HAS_PCH_CNP(dev_priv))
>> > +		return cnp_ddc_pin_map[vbt_pin];
>
> Do we need an ARRAY_SIZE() check? I didn't actually check how many bits
> we have in the VBT for this.

Oh yes, it's u8.

BR,
Jani.


>
>> > +
>> > +	return vbt_pin;
>> > +}
>> > +
>> >  static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
>> >  			   u8 bdb_version)
>> >  {
>> > @@ -1164,16 +1179,7 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
>> >  		DRM_DEBUG_KMS("Port %c is internal DP\n", port_name(port));
>> >  
>> >  	if (is_dvi) {
>> > -		info->alternate_ddc_pin = ddc_pin;
>> > -
>> > -		/*
>> > -		 * All VBTs that we got so far for B Stepping has this
>> > -		 * information wrong for Port D. So, let's just ignore for now.
>> > -		 */
>> > -		if (IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0) &&
>> > -		    port == PORT_D) {
>> > -			info->alternate_ddc_pin = 0;
>> > -		}
>> > +		info->alternate_ddc_pin = get_ddc_pin(dev_priv, ddc_pin);
>> >  
>> >  		sanitize_ddc_pin(dev_priv, port);
>> >  	}
>> > diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
>> > index 7e2a96712d07..dfc9f7a43668 100644
>> > --- a/drivers/gpu/drm/i915/intel_vbt_defs.h
>> > +++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
>> > @@ -308,6 +308,21 @@ struct bdb_general_features {
>> >  
>> >  #define LEGACY_CHILD_DEVICE_CONFIG_SIZE		33
>> >  
>> > +/* DDC Bus DDI Type 155+ */
>> > +enum vbt_gmbus_ddi {
>> > +	DDC_BUS_DDI_B = 0x1,
>> > +	DDC_BUS_DDI_C,
>> > +	DDC_BUS_DDI_D,
>> > +	DDC_BUS_DDI_F,
>> > +};
>> > +
>> > +enum bspec_gmbus_pin {
>> > +	GMBUS_PIN_1 = 0x1,
>> > +	GMBUS_PIN_2,
>> > +	GMBUS_PIN_3,
>> > +	GMBUS_PIN_4,
>> 
>> You already have these defined in i915_reg.h. The naming isn't pretty,
>> but the above doesn't make much sense either.
>
> +1
>
>> 
>> > +};
>> > +
>> >  /*
>> >   * The child device config, aka the display device data structure, provides a
>> >   * description of a port and its configuration on the platform.
>> 
>> -- 
>> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center
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