Re: [PATCH v4 5/6] drm/i915: enable scrambling

[Ander Conselvan De Oliveira <conselvan2@gmail.com>]

On Thu, 2017-02-23 at 10:01 +0530, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 2/22/2017 10:59 PM, Ville Syrjälä wrote:
> > On Wed, Feb 22, 2017 at 06:48:30PM +0530, Shashank Sharma 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.
> > > 
> > > 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.
> > > 
> > > V3: Addressed review comments from Jani
> > > - In comments, function names, use "sink" instead of "monitor",
> > >    so that the implementation could be close to the language of
> > >    HDMI spec.
> > > 
> > > V4: Addressed review comment from Maarten
> > > - scrambling -> hdmi_scrambling
> > >    high_tmds_clock_ratio -> hdmi_high_tmds_clock_ratio
> > > 
> > > Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> > > ---
> > >   drivers/gpu/drm/i915/i915_reg.h   |   4 ++
> > >   drivers/gpu/drm/i915/intel_ddi.c  |  28 ++++++++++
> > >   drivers/gpu/drm/i915/intel_drv.h  |  14 +++++
> > >   drivers/gpu/drm/i915/intel_hdmi.c | 108 ++++++++++++++++++++++++++++++++++++++
> > >   4 files changed, 154 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > index 141a5c1..81cf10b 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -7819,7 +7819,11 @@ enum {
> > >   #define  TRANS_DDI_EDP_INPUT_B_ONOFF	(5<<12)
> > >   #define  TRANS_DDI_EDP_INPUT_C_ONOFF	(6<<12)
> > >   #define  TRANS_DDI_DP_VC_PAYLOAD_ALLOC	(1<<8)
> > > +#define  TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE (1<<7)
> > > +#define  TRANS_DDI_HDMI_SCRAMBLER_RESET_FREQ (1<<6)
> > >   #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 cd6fedd..bd8293d 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;
> > > @@ -1843,6 +1848,21 @@ 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)) {
> > > +			struct intel_crtc *crtc = to_intel_crtc(encoder->crtc);
> > > +			/*
> > > +			 * GLK sports a native HDMI 2.0 controller. If required
> > > +			 * clock rate is > 340 Mhz && scrambling is supported
> > > +			 * by sink, 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_sink_scrambling(intel_encoder,
> > > +						conn_state->connector,
> > > +						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.
> > > @@ -1875,6 +1895,14 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder,
> > >   	if (old_crtc_state->has_audio)
> > >   		intel_audio_codec_disable(intel_encoder);
> > >   
> > > +	if (type == INTEL_OUTPUT_HDMI) {
> > > +		struct intel_crtc *intel_crtc = to_intel_crtc(encoder->crtc);
> > > +
> > > +		intel_hdmi_handle_sink_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 821c57c..c7262d7 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -691,6 +691,12 @@ struct intel_crtc_state {
> > >   
> > >   	/* Gamma mode programmed on the pipe */
> > >   	uint32_t gamma_mode;
> > > +
> > > +	/* HDMI scrambling status (sink) */
> > > +	bool hdmi_scrambling;
> > > +
> > > +	/* HDMI High TMDS char rate ratio (sink) */
> > > +	bool hdmi_high_tmds_clock_ratio;
> > >   };
> > >   
> > >   struct vlv_wm_state {
> > > @@ -1609,6 +1615,14 @@ 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_sink_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 a580de8..c44beee 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 +1796,113 @@ static void intel_hdmi_destroy(struct drm_connector *connector)
> > >   	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
> > >   }
> > >   
> > > +void intel_hdmi_handle_sink_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,

There's only two letters missing. Maybe just spell adapter.

> > > +							  intel_hdmi->ddc_bus);
> > > +
> > > +	if (!scrambling->supported)
> > > +		return;
> > > +
> > > +	DRM_DEBUG_KMS("Setting sink scrambling for enc:%s connector:%s\n",
> > > +			intel_encoder->base.name, connector->name);
> > > +
> > > +	if (enable) {
> > > +
> > > +		if (mode->clock > 340000) {
> > > +			/* Set TMDS bit clock ratio to 1/40 */
> > > +			config->hdmi_high_tmds_clock_ratio =
> > > +				drm_scdc_set_high_tmds_clock_ratio(adptr);
> > 
> > You're not allowed to muck with the state anymore. All state computation
> > should happen in the .compute_config hook.
> 
> ok, let me re-arrange this function in such a way that I do the config 
> update part in compute_config
> > > +			if (!config->hdmi_high_tmds_clock_ratio) {
> > > +				DRM_ERROR("Set high TMDS ratio failed\n");
> > > +				return;
> > > +			}
> > > +
> > > +			/* Enable sink scrambling */
> > > +			config->hdmi_scrambling =
> > > +					drm_scdc_enable_scrambling(adptr);
> > > +			if (!config->hdmi_scrambling) {
> > > +				DRM_ERROR("Can't enable sink scrambling\n");
> > > +				return;
> > > +			}
> > > +		}
> > > +
> > > +		/* Few sinks support scrambling at clocks <=340 MHz too */
> > > +		if (!config->hdmi_scrambling && scrambling->low_rates) {
> > > +			config->hdmi_scrambling =
> > > +					drm_scdc_enable_scrambling(adptr);
> > > +			if (!config->hdmi_scrambling)
> > > +				DRM_ERROR("Can't enable sink scrambling\n");
> > > +		}
> > > +
> > > +		return;
> > > +	}
> > > +
> > > +	if (config->hdmi_high_tmds_clock_ratio) {
> > > +		/* Set TMDS bit clock ratio back to 1/10 */
> > > +		config->hdmi_high_tmds_clock_ratio =
> > > +			!(drm_scdc_clear_high_tmds_clock_ratio(adptr));
> > > +		if (config->hdmi_high_tmds_clock_ratio)
> > > +			DRM_ERROR("Reset high TMDS ratio failed\n");
> > > +	}
> > > +
> > > +	if (config->hdmi_scrambling) {
> > > +		/* Disable sink scrambling */
> > > +		config->hdmi_scrambling = !(drm_scdc_disable_scrambling(adptr));
> > > +		if (config->hdmi_scrambling)
> > > +			DRM_ERROR("Disable sink scrambling failed\n");
> > > +	}
> > > +}
> > > +
> > > +static inline uint32_t _intel_hdmi_set_source_scrambling(uint32_t hdmi_config)
> > > +{
> > > +	return hdmi_config |= (TRANS_DDI_HDMI_SCRAMBLING |
> > > +			TRANS_DDI_HDMI_SCRAMBLER_RESET_FREQ |
> > > +			TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE);
> > > +}
> > > +
> > > +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 |
> > > +		TRANS_DDI_HIGH_TMDS_CHAR_RATE |
> > > +		TRANS_DDI_HDMI_SCRAMBLER_RESET_FREQ |
> > > +		TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE);
> > > +
> > > +	if (mode->clock <= 340000) {
> > > +		/* Few sinks support scrambling at rate < 340 MHz too */
> > > +		if (scrambling->low_rates)
> > > +			hdmi_config =
> > > +				_intel_hdmi_set_source_scrambling(hdmi_config);
> > > +		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 = _intel_hdmi_set_source_scrambling(hdmi_config);
> > > +
> > > +	return hdmi_config;
> > > +}
> > 
> > Seems overly complicated to me. It could just be something simple like:
> > 
> > void intel_ddi_enable_transcoder_func(struct drm_crtc *crtc)
> > {
> > 	...
> > 	if (config->hdmi_scrambling)
> > 		temp |= TRANS_DDI_HDMI_SCRAMBLING;
> > 	
> > 	if (config->whatever)
> > 		temp |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
> > 	...
> > }
> 
> I know it appears like complicated, but actually the requirement is 
> complicated:
> - if clock is > 340 Mhz, set scrambling && set_high_tmds_clock_ratio
> - if clock is < 340 Mhz, but if monitor supports scrambling at lower 
> clocks, set scrambling only (not tmds_clock_ratio)
> - to set scrambling, we have to first check if scrambling is supported 
> in monitor
> So to meet all these condition, you will end up with something like 
> what's implemented above.
> Do you see a  better way ?

Put that intel_hdmi_compute_config() so you check it only once, i.e.:

if (clock > 340 || scrambling->low_rates)
	config->hdmi_scrambling = true;

if (clock > 340)
	config->hdmi_high_tmds = true;

Then you can do just as Ville said above in intel_ddi_enable_transcoder_func().
And also for the sink part, no need to check the input values again:

if (config->hdmi_high_tmds)
	if (!drm_scdc_set_high_tmds_clock_ratio(adapter, enable))
		DRM_ERROR();

if (config->hdmi_scrambing)
	if (!drm_scdc_set_scrambling(adapter, enable))
		DRM_ERROR();

At least that's how I'd interpret what Ville wrote.

Ander


> 
> - Shashank
> > 
> > > +
> > >   static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
> > >   			     enum port port)
> > >   {
> > > -- 
> > > 1.9.1
> 
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