Re: [PATCH 1/7] drm/i915: add lspcon vbt bit parsing

["Sharma, Shashank" <shashank.sharma@intel.com>]

Thanks for the review, Jani.

Regards
Shashank

On 3/22/2016 9:24 PM, Jani Nikula wrote:
> On Tue, 22 Mar 2016, Shashank Sharma <shashank.sharma@intel.com> wrote:
>> LSPCON can be configured on a port using VBT entry.
>> This patch adds code to parse VBT and detect presence of
>> LSPCON for a ddi port.
>>
>> Signed-off-by: Akashdeep Sharma <akashdeep.sharma@intel.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_drv.h       |  1 +
>>   drivers/gpu/drm/i915/intel_bios.c     | 42 +++++++++++++++++++++++++++++++++++
>>   drivers/gpu/drm/i915/intel_vbt_defs.h |  1 +
>>   3 files changed, 44 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index f330a53..cbd40de 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -3373,6 +3373,7 @@ bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv);
>>   bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin);
>>   bool intel_bios_is_port_edp(struct drm_i915_private *dev_priv, enum port port);
>>   bool intel_bios_is_dsi_present(struct drm_i915_private *dev_priv, enum port *port);
>> +bool intel_bios_is_lspcon_preset(struct drm_device *dev, enum port port);
>>
>>   /* intel_opregion.c */
>>   #ifdef CONFIG_ACPI
>> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
>> index 083003b..a04ab5c 100644
>> --- a/drivers/gpu/drm/i915/intel_bios.c
>> +++ b/drivers/gpu/drm/i915/intel_bios.c
>> @@ -1588,3 +1588,45 @@ bool intel_bios_is_dsi_present(struct drm_i915_private *dev_priv,
>>
>>   	return false;
>>   }
>> +
>
> Please add kernel-doc comment like all the other intel_bios_is_*
> functions have.
>
Ok,
>> +bool
>> +intel_bios_is_lspcon_preset(struct drm_device *dev, enum port port)
>
> You mean is *present*?
>
Well, this is embarrassing :) yes it was supposed to be present.
> Please pass struct drm_i915_private *dev_priv instead of dev.
>
Ok
>> +{
>> +	unsigned char i;
>> +	enum port dvo_port = 0;
>> +	struct drm_i915_private *dev_priv = dev->dev_private;
>> +
>> +	/* LSPCON is supported only for GEN 9 */
>> +	if (!IS_GEN9(dev))
>> +		return false;
>> +
>> +	/* Check if lspcon is supported in VBT */
>> +	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
>> +		if (!dev_priv->vbt.child_dev[i].common.lspcon)
>
> I think to be defensive we should also check for bdb version >=
> 192. That we could check before the loop along with the gen check.
>
Yes, this can be done.
>> +			continue;
>> +
>> +		switch (dev_priv->vbt.child_dev[i].common.dvo_port) {
>> +		case DVO_PORT_DPB:
>> +			dvo_port = PORT_B;
>> +			break;
>> +
>> +		case DVO_PORT_DPC:
>> +			dvo_port = PORT_C;
>> +			break;
>> +
>> +		case DVO_PORT_DPD:
>> +			dvo_port = PORT_D;
>> +			break;
>> +
>> +		default:
>> +			continue;
>> +		}
>> +
>> +		if (dvo_port == port) {
>> +			DRM_DEBUG_DRIVER("LSPCON configured on port %c\n",
>> +			port_name(port));
>> +			return true;
>> +		}
>> +	}
>> +	return false;
>> +}
>> diff --git a/drivers/gpu/drm/i915/intel_vbt_defs.h b/drivers/gpu/drm/i915/intel_vbt_defs.h
>> index 749dcea..0066b24 100644
>> --- a/drivers/gpu/drm/i915/intel_vbt_defs.h
>> +++ b/drivers/gpu/drm/i915/intel_vbt_defs.h
>> @@ -276,6 +276,7 @@ struct common_child_dev_config {
>>   	u8 flags_1;
>>   	u8 not_common3[13];
>>   	u8 iboost_level;
>> +	u8 lspcon:1;
>
> Huh? AFAICT from the spec, lspcon is bit 2 in flags_1. You could define
> flags_1 in terms of bitfields, including IBOOST_ENABLE.
>
I am not sure about this, let me go to VBT spec again, if there is a 
recent change. Will update you on this.
>>   } __packed;
>
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