Re: [Intel-gfx] [PATCH v6 5/6] drm/i915: enable scrambling

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On Fri, 2017-03-03 at 17:33 +0530, Sharma, Shashank wrote:
> Thanks for the review Ander. My comments inline.
> 
> Shashank
> 
> On 3/3/2017 3:22 PM, Ander Conselvan De Oliveira wrote:
> > On Fri, 2017-03-03 at 11:59 +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
> > > 
> > > V5: Addressed review comments from Ville and Ander
> > >   - Do not modifiy the crtc_state after compute_config. Move all
> > >     scrambling and tmds_clock_ratio calcutations to compute_config.
> > >   - While setting scrambling for source/sink, do not check the
> > >     conditions again, just go by the crtc_state flags. This will
> > >     simplyfy the condition checks.
> > > 
> > > V6: Addressed review comments from Ville
> > >   - Do not add IS_GLK check in disable/enable function, instead add it
> > >     in compute_config, while setting state flags.
> > >   - Remove unnecessary paranthesis.
> > >   - Simplyfy handle_sink_scrambling function as suggested.
> > >   - Add readout code for scrambling status in get_ddi_config and add a
> > >     check for the same in pipe_config_compare.
> > > 
> > > Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/i915/i915_reg.h      |  7 ++++
> > >   drivers/gpu/drm/i915/intel_ddi.c     | 33 ++++++++++++++++
> > >   drivers/gpu/drm/i915/intel_display.c |  5 +++
> > >   drivers/gpu/drm/i915/intel_drv.h     | 14 +++++++
> > >   drivers/gpu/drm/i915/intel_hdmi.c    | 74 ++++++++++++++++++++++++++++++++++++
> > >   5 files changed, 133 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > > index 4906ce4d..f7891ac 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -7824,7 +7824,14 @@ 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)
> > > +#define  TRANS_DDI_HDMI_SCRAMBLING_MASK (TRANS_DDI_HDMI_SCRAMBLER_CTS_ENABLE \
> > > +					| TRANS_DDI_HDMI_SCRAMBLER_RESET_FREQ \
> > > +						| TRANS_DDI_HDMI_SCRAMBLING)
> > 
> > Last line is misaligned.
> 
> Ok.
> > >   
> > >   /* 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 a7c08d7..d0c6927 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -1311,6 +1311,11 @@ 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, temp);
> > 
> > This whole hunk could just be:
> > 
> > +	if (config->hdmi_scrambling)
> > +		hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING_MASK;
> > +
> > +	if (config->hdmi_high_tmds_clock_ratio)
> > +		hdmi_config |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
> > 
> > No need to check for GLK here, since the compute config code already did.
> 
> As I was emphasizing in the previous review comments, having two 
> separate functions, one to set source_scrambling and
> other to set sink_scrambling makes it easy to follow up, due to design 
> symmetry, and in that case you need not to refer
> to bspec to find out which all registers be dealing with scrambling , 
> just check for scrambling control functions. So I was insisting
> on keeping them.

But that design creates an asymmetry when it comes to checking all bits that are
enabled in TRANS_DDI_FUNC_CTL() that involves function-hopping. Maybe it is just
a matter of different taste. But for the more practical problem of finding what
bits are involved in enabling scrambling, I think

    git grep hdmi_scrambling

will do a good enough job.

> 
> But anyways, both you and Ville are insisting on keeping it inline, so 
> lets keep it that way.
> > >   	} else if (type == INTEL_OUTPUT_ANALOG) {
> > >   		temp |= TRANS_DDI_MODE_SELECT_FDI;
> > >   		temp |= (intel_crtc->config->fdi_lanes - 1) << 1;
> > > @@ -1885,6 +1890,21 @@ 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);
> > 
> > This function receives a pipe_config pointer as argument. Use that instead of
> > crtc->config.
> 
> Ok.
> > > +		}
> > > +
> > >   		/* In HDMI/DVI mode, the port width, and swing/emphasis values
> > >   		 * are ignored so nothing special needs to be done besides
> > >   		 * enabling the port.
> > > @@ -1917,6 +1937,14 @@ 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);
> > >   
> > > @@ -2044,6 +2072,11 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
> > >   
> > >   		if (intel_hdmi->infoframe_enabled(&encoder->base, pipe_config))
> > >   			pipe_config->has_infoframe = true;
> > > +
> > > +		if (temp & TRANS_DDI_HDMI_SCRAMBLING_MASK)

I missed this the first time, but we say hdmi_scrambling is enabled if any of
those bits in the mask is set. Is that really what we want? Or should this check
specifically for the TRANS_DDI_HDMI_SCRAMBLING bit or all the bits set?

> > > +			pipe_config->hdmi_scrambling = true;
> > > +		if (temp & TRANS_DDI_HIGH_TMDS_CHAR_RATE)
> > > +			pipe_config->hdmi_high_tmds_clock_ratio = true;
> > 
> > Hmm, we might need a IS_GLK here, since these bits only exist in that platform.
> > I believe they should read zero though, since they are listed are reserved.
> > Dunno.
> 
> Hmm, I dont think there would be a way to set the reserved bits though, 
> so we can keep it. In this way the
> only place we are checking and setting the platform is compute_config.

Yeah, with the change to check the state for non-GLK too, we get a WARN if this
fails, so seems ok.

> > >   		/* fall through */
> > >   	case TRANS_DDI_MODE_SELECT_DVI:
> > >   		pipe_config->lane_count = 4;
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 99e8d9c..c017ed3 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -11662,6 +11662,11 @@ static void __printf(3, 4)
> > >   	if ((INTEL_GEN(dev_priv) < 8 && !IS_HASWELL(dev_priv)) ||
> > >   	    IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> > >   		PIPE_CONF_CHECK_I(limited_color_range);
> > > +	if (IS_GEMINILAKE(dev_priv)) {
> > 
> > No need to check for GLK here. The configuration should never be set for other
> > platforms. If it is set, that's a bug and we want verify_crtc_state() to tells
> > us about it.
> 
> Agree, will remove this.
> > 
> > > +		PIPE_CONF_CHECK_I(hdmi_scrambling);
> > > +		PIPE_CONF_CHECK_I(hdmi_high_tmds_clock_ratio);
> > > +	}
> > > +
> > >   	PIPE_CONF_CHECK_I(has_infoframe);
> > >   
> > >   	PIPE_CONF_CHECK_I(has_audio);
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index e6fbbee..baefbaa 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -695,6 +695,12 @@ 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 {
> > > @@ -1626,6 +1632,14 @@ 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 intel_crtc_state *config,
> > > +					uint32_t hdmi_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 c2184f7..0a1ae03 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>
> > > @@ -1316,6 +1317,7 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
> > >   	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(&encoder->base);
> > >   	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > >   	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
> > > +	struct drm_scdc *scdc = &conn_state->connector->display_info.hdmi.scdc;
> > >   	int clock_8bpc = pipe_config->base.adjusted_mode.crtc_clock;
> > >   	int clock_12bpc = clock_8bpc * 3 / 2;
> > >   	int desired_bpp;
> > > @@ -1385,6 +1387,16 @@ bool intel_hdmi_compute_config(struct intel_encoder *encoder,
> > >   
> > >   	pipe_config->lane_count = 4;
> > >   
> > > +	if (scdc->scrambling.supported && IS_GEMINILAKE(dev_priv)) {
> > > +		if (scdc->scrambling.low_rates)
> > > +			pipe_config->hdmi_scrambling = true;
> > > +
> > > +		if (pipe_config->port_clock > 340000) {
> > > +			pipe_config->hdmi_scrambling = true;
> > > +			pipe_config->hdmi_high_tmds_clock_ratio = true;
> > > +		}
> > > +	}
> > > +
> > >   	return true;
> > >   }
> > >   
> > > @@ -1794,6 +1806,68 @@ 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_i915_private *dev_priv = connector->dev->dev_private;
> > > +	struct drm_scrambling *scrambling =
> > > +				&connector->display_info.hdmi.scdc.scrambling;
> > > +	struct i2c_adapter *adptr = intel_gmbus_get_adapter(dev_priv,
> > > +							  intel_hdmi->ddc_bus);
> > > +	bool ret;
> > > +
> > > +	if (!scrambling->supported)
> > > +		return;
> > > +
> > > +	DRM_DEBUG_KMS("Setting sink scrambling for enc:%s connector:%s\n",
> > > +			intel_encoder->base.name, connector->name);
> > > +
> > > +	if (config->hdmi_high_tmds_clock_ratio) {
> > > +		/* Set TMDS bit clock ratio to 1/40 or 1/10 */
> > > +		ret = drm_scdc_set_high_tmds_clock_ratio(adptr, enable);
> > > +		if (!ret) {
> > > +			DRM_ERROR("Set TMDS ratio failed\n");
> > > +			return;
> > > +		}
> > > +	}
> > > +
> > > +	if (config->hdmi_scrambling) {
> > > +		/* Enable/disable sink scrambling */
> > > +		ret = drm_scdc_set_scrambling(adptr, enable);
> > > +		if (!ret) {
> > > +			DRM_ERROR("Set sink scrambling failed\n");
> > > +			return;
> > > +		}
> > > +	}
> > > +
> > > +	DRM_DEBUG_KMS("sink scrambling handled\n");
> > > +}
> > > +
> > > +uint32_t
> > > +intel_hdmi_handle_source_scrambling(struct intel_encoder *intel_encoder,
> > > +			struct intel_crtc_state *config, 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;
> > > +
> > > +	DRM_DEBUG_KMS("Setting scrambling for enc:%s connector:%s\n",
> > > +			intel_encoder->base.name, connector->name);
> > 
> > Instead of debugging here, print the hdmi scrambling values in
> > intel_dump_pipe_config().
> 
> I am also interested in which encoder and connector are we setting the 
> values for, is it that bad :) ?

The debug for the modeset should tell you that, but IMO it would be ok to leave
this extra debug message if the function would still exist.

Ander

> > 
> > > +	hdmi_config &= ~(TRANS_DDI_HDMI_SCRAMBLING_MASK |
> > > +		TRANS_DDI_HIGH_TMDS_CHAR_RATE);
> > 
> > This is unnecessary. The hunk below belongs in
> > intel_ddi_enable_transcoder_func() and that function does not do read-modify-
> > write. Any bit that is not explicitly set is zero. I think things are just
> > simpler if this function doesn't exist.
> 
> Yeah, will do that.
> > Ander
> > 
> > > +	if (config->hdmi_scrambling)
> > > +		hdmi_config |= TRANS_DDI_HDMI_SCRAMBLING_MASK;
> > > +
> > > +	if (config->hdmi_high_tmds_clock_ratio)
> > > +		hdmi_config |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
> > > +
> > > +	return hdmi_config;
> > > +}
> > > +
> > >   static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
> > >   			     enum port port)
> > >   {
> 
> 
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