Re: [PATCH v2 5/6] drm/i915: enable scrambling

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

Regards

Shashank


On 2/7/2017 3:51 PM, Jani Nikula wrote:
> On Mon, 06 Feb 2017, Shashank Sharma <shashank.sharma@intel.com> wrote:
>> Geminilake platform sports a native HDMI 2.0 controller, and is
>> capable of driving pixel-clocks upto 594Mhz. HDMI 2.0 spec
>> mendates scrambling for these higher clocks, for reduced RF footprint.
>>
>> This patch checks if the monitor supports scrambling, and if required,
>> enables it during the modeset.
> Throughout this series, but particularly in this patch, I'd prefer using
> the term "sink" instead of "monitor" everywhere. The HDMI specifications
> use source and sink almost exclusively.
>
> BR,
> Jani.
Sure, can be done.
- Shashank
>
>> V2: Addressed review comments from Ville:
>> - Do not track scrambling status in DRM layer, track somewhere in
>>    driver like in intel_crtc_state.
>> - Don't talk to monitor at such a low layer, set monitor scrambling
>>    in intel_enable_ddi() before enabling the port.
>>
>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_reg.h   |  2 ++
>>   drivers/gpu/drm/i915/intel_ddi.c  | 26 +++++++++++++++
>>   drivers/gpu/drm/i915/intel_drv.h  | 11 ++++++
>>   drivers/gpu/drm/i915/intel_hdmi.c | 70 +++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 109 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>> index 495b789..cc85892 100644
>> --- a/drivers/gpu/drm/i915/i915_reg.h
>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>> @@ -7807,6 +7807,8 @@ enum {
>>   #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6<<12)
>>   #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1<<8)
>>   #define  TRANS_DDI_BFI_ENABLE		(1<<4)
>> +#define  TRANS_DDI_HIGH_TMDS_CHAR_RATE	(1<<4)
>> +#define  TRANS_DDI_HDMI_SCRAMBLING	(1<<0)
>>   
>>   /* DisplayPort Transport Control */
>>   #define _DP_TP_CTL_A			0x64040
>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
>> index 9a9a670..cc7e091 100644
>> --- a/drivers/gpu/drm/i915/intel_ddi.c
>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
>> @@ -1278,6 +1278,11 @@ void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
>>   			temp |= TRANS_DDI_MODE_SELECT_HDMI;
>>   		else
>>   			temp |= TRANS_DDI_MODE_SELECT_DVI;
>> +
>> +		if (IS_GEMINILAKE(dev_priv))
>> +			temp = intel_hdmi_handle_source_scrambling(
>> +				intel_encoder,
>> +				&intel_crtc->config->base.adjusted_mode, temp);
>>   	} else if (type == INTEL_OUTPUT_ANALOG) {
>>   		temp |= TRANS_DDI_MODE_SELECT_FDI;
>>   		temp |= (intel_crtc->config->fdi_lanes - 1) << 1;
>> @@ -1845,6 +1850,21 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder,
>>   		struct intel_digital_port *intel_dig_port =
>>   			enc_to_dig_port(encoder);
>>   
>> +		if (IS_GEMINILAKE(dev_priv)) {
>> +			/*
>> +			 * GLK sports a native HDMI 2.0 controller. If required
>> +			 * clock rate is > 340 Mhz && scrambling is supported
>> +			 * by monitor, enable scrambling before enabling the
>> +			 * HDMI 2.0 port. The sink can choose to disable the
>> +			 * scrambling if it doesn't detect a scrambled within
>> +			 * 100 ms.
>> +			 */
>> +			intel_hdmi_handle_monitor_scrambling(intel_encoder,
>> +							conn_state->connector,
>> +							intel_crtc->config,
>> +							true);
>> +		}
>> +
>>   		/* In HDMI/DVI mode, the port width, and swing/emphasis values
>>   		 * are ignored so nothing special needs to be done besides
>>   		 * enabling the port.
>> @@ -1885,6 +1905,12 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder,
>>   		intel_display_power_put(dev_priv, POWER_DOMAIN_AUDIO);
>>   	}
>>   
>> +	if (type == INTEL_OUTPUT_HDMI) {
>> +		intel_hdmi_handle_monitor_scrambling(intel_encoder,
>> +						old_conn_state->connector,
>> +						intel_crtc->config, false);
>> +	}
>> +
>>   	if (type == INTEL_OUTPUT_EDP) {
>>   		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>>   
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index 393f243..300353c 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -681,6 +681,9 @@ struct intel_crtc_state {
>>   
>>   	/* Gamma mode programmed on the pipe */
>>   	uint32_t gamma_mode;
>> +
>> +	/* HDMI scrambling status (monitor) */
>> +	bool scrambling;
>>   };
>>   
>>   struct vlv_wm_state {
>> @@ -1588,6 +1591,14 @@ void intel_hdmi_init_connector(struct intel_digital_port *intel_dig_port,
>>   bool intel_hdmi_compute_config(struct intel_encoder *encoder,
>>   			       struct intel_crtc_state *pipe_config,
>>   			       struct drm_connector_state *conn_state);
>> +uint32_t
>> +intel_hdmi_handle_source_scrambling(struct intel_encoder *intel_encoder,
>> +					struct drm_display_mode *mode,
>> +					uint32_t config);
>> +void intel_hdmi_handle_monitor_scrambling(struct intel_encoder *intel_encoder,
>> +					struct drm_connector *connector,
>> +					struct intel_crtc_state *config,
>> +					bool enable);
>>   void intel_dp_dual_mode_set_tmds_output(struct intel_hdmi *hdmi, bool enable);
>>   
>>   
>> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
>> index ebae2bd..41d3309 100644
>> --- a/drivers/gpu/drm/i915/intel_hdmi.c
>> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
>> @@ -34,6 +34,7 @@
>>   #include <drm/drm_atomic_helper.h>
>>   #include <drm/drm_crtc.h>
>>   #include <drm/drm_edid.h>
>> +#include <drm/drm_scdc_helper.h>
>>   #include "intel_drv.h"
>>   #include <drm/i915_drm.h>
>>   #include <drm/intel_lpe_audio.h>
>> @@ -1795,6 +1796,75 @@ static void intel_hdmi_destroy(struct drm_connector *connector)
>>   	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
>>   }
>>   
>> +void intel_hdmi_handle_monitor_scrambling(struct intel_encoder *intel_encoder,
>> +				       struct drm_connector *connector,
>> +				       struct intel_crtc_state *config,
>> +				       bool enable)
>> +{
>> +	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&intel_encoder->base);
>> +	struct drm_scdc *scdc = &connector->display_info.hdmi.scdc;
>> +	struct drm_scrambling *scrambling = &scdc->scrambling;
>> +	struct drm_display_mode *mode = &config->base.adjusted_mode;
>> +	struct drm_i915_private *dev_priv = connector->dev->dev_private;
>> +	struct i2c_adapter *adptr = intel_gmbus_get_adapter(dev_priv,
>> +							  intel_hdmi->ddc_bus);
>> +
>> +	if (!scrambling->supported)
>> +		return;
>> +
>> +	DRM_DEBUG_KMS("Setting monitor scrambling for enc:%s connector:%s\n",
>> +			intel_encoder->base.name, connector->name);
>> +
>> +	/* Enable monitor scrambling */
>> +	if (enable) {
>> +		if (mode->clock > 340000 || scrambling->low_rates) {
>> +			config->scrambling = drm_scdc_enable_scrambling(adptr);
>> +			if (!config->scrambling)
>> +				DRM_ERROR("Can't enable monitor scrambling\n");
>> +		}
>> +		return;
>> +	}
>> +
>> +	/* Disable monitor scrambling */
>> +	if (config->scrambling) {
>> +		config->scrambling = !(drm_scdc_disable_scrambling(adptr));
>> +		if (config->scrambling)
>> +			DRM_ERROR("Can't disable monitor scrambling\n");
>> +	}
>> +
>> +}
>> +
>> +uint32_t
>> +intel_hdmi_handle_source_scrambling(struct intel_encoder *intel_encoder,
>> +			struct drm_display_mode *mode, uint32_t hdmi_config)
>> +{
>> +	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&intel_encoder->base);
>> +	struct drm_connector *connector = &intel_hdmi->attached_connector->base;
>> +	struct drm_hdmi_info *hdmi_info = &connector->display_info.hdmi;
>> +	struct drm_scrambling *scrambling = &hdmi_info->scdc.scrambling;
>> +
>> +	DRM_DEBUG_KMS("Setting scrambling for enc:%s connector:%s\n",
>> +			intel_encoder->base.name, connector->name);
>> +
>> +	hdmi_config &= ~TRANS_DDI_HDMI_SCRAMBLING;
>> +	hdmi_config &= ~TRANS_DDI_HIGH_TMDS_CHAR_RATE;
>> +
>> +	if (mode->clock <= 340000) {
>> +		/* Few sinks support scrambling at rate < 340 MHz too */
>> +		if (scrambling->low_rates)
>> +			hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING;
>> +		return hdmi_config;
>> +	}
>> +
>> +	/* Scrambling or not, if clock > 340 MHz, set high char rate */
>> +	hdmi_config |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
>> +
>> +	if (scrambling->supported)
>> +		hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING;
>> +
>> +	return hdmi_config;
>> +}
>> +
>>   static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
>>   			     enum port port)
>>   {

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