Re: [PATCH v8 5/6] drm/i915: enable scrambling

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Regards

Shashank


On 3/8/2017 7:56 PM, Ville Syrjälä wrote:
On Wed, Mar 08, 2017 at 07:50:45PM +0200, Sharma, Shashank wrote:
Regards

Shashank


On 3/8/2017 7:44 PM, Ville Syrjälä wrote:
On Wed, Mar 08, 2017 at 07:26:45PM +0200, Sharma, Shashank wrote:
Regards

Shashank


On 3/8/2017 7:17 PM, Ville Syrjälä wrote:
On Wed, Mar 08, 2017 at 07:07:48PM +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.

V7: Addressed review comments from Ander/Ville
    - No separate function for source scrambling, make it inline
    - Align the last line of the macro TRANS_DDI_HDMI_SCRAMBLING_MASK
    - Do not add platform check while setting source scrambling
    - Use pipe_config instead of crtc->config to set sink scrambling
    - To readout scrambling status, Compare with SCRAMBLING_MASK
      not any of its bits
    - Remove platform check in intel_pipe_config_compare while checking
      scrambling status

V8: Fixed mege conflict, Addressed review comments from Ander
    - Remove the desciption/comment about scrambling fom the caller, move
      it to the function
    - Move the IS_GLK check into scrambling function
    - Fix alignment

Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
---
    drivers/gpu/drm/i915/i915_reg.h      |  7 ++++
    drivers/gpu/drm/i915/intel_ddi.c     | 19 +++++++++++
    drivers/gpu/drm/i915/intel_display.c |  3 ++
    drivers/gpu/drm/i915/intel_drv.h     | 10 ++++++
    drivers/gpu/drm/i915/intel_hdmi.c    | 62 ++++++++++++++++++++++++++++++++++++
    5 files changed, 101 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cc843f9..2d50fdc 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7830,7 +7830,14 @@ 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)
/* 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 0467676..b3e4c4a 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1309,6 +1309,11 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state)
    			temp |= TRANS_DDI_MODE_SELECT_HDMI;
    		else
    			temp |= TRANS_DDI_MODE_SELECT_DVI;
+
+		if (crtc_state->hdmi_scrambling)
+			temp |= TRANS_DDI_HDMI_SCRAMBLING_MASK;
+		if (crtc_state->hdmi_high_tmds_clock_ratio)
+			temp |= TRANS_DDI_HIGH_TMDS_CHAR_RATE;
    	} else if (type == INTEL_OUTPUT_ANALOG) {
    		temp |= TRANS_DDI_MODE_SELECT_FDI;
    		temp |= (crtc_state->fdi_lanes - 1) << 1;
@@ -1882,6 +1887,9 @@ static void intel_enable_ddi(struct intel_encoder *intel_encoder,
    		struct intel_digital_port *intel_dig_port =
    			enc_to_dig_port(encoder);
+ intel_hdmi_handle_sink_scrambling(intel_encoder,
+			conn_state->connector, pipe_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.
@@ -1914,6 +1922,11 @@ 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) {
+		intel_hdmi_handle_sink_scrambling(intel_encoder,
+			old_conn_state->connector, old_crtc_state, false);
+	}
+
    	if (type == INTEL_OUTPUT_EDP) {
    		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
@@ -2040,6 +2053,12 @@ 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) ==
+				TRANS_DDI_HDMI_SCRAMBLING_MASK)
+			pipe_config->hdmi_scrambling = true;
+		if (temp & TRANS_DDI_HIGH_TMDS_CHAR_RATE)
+			pipe_config->hdmi_high_tmds_clock_ratio = true;
    		/* 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 e77ca7d..fb5e670 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11701,6 +11701,9 @@ 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);
+
+	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 3af20c1..50d680c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -729,6 +729,12 @@ struct intel_crtc_state {
/* bitmask of visible planes (enum plane_id) */
    	u8 active_planes;
+
+	/* HDMI scrambling status */
+	bool hdmi_scrambling;
+
+	/* HDMI High TMDS char rate ratio */
+	bool hdmi_high_tmds_clock_ratio;
    };
struct intel_crtc {
@@ -1623,6 +1629,10 @@ 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);
+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..4585aa8 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 +1806,56 @@ static void intel_hdmi_destroy(struct drm_connector *connector)
    	intel_hdmi->aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
    }
+/*
+ * This function handles scrambling on HDMI 2.0 capable sinks.
+ * If required clock rate is > 340 Mhz && scrambling is supported by sink
+ * it enables scrambling. This should be called before enabling the HDMI
+ * 2.0 port, as the sink can choose to disable the scrambling if it doesn't
+ * detect a scrambled clock within 100 ms.
+ */
+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;
+
+	if (!IS_GEMINILAKE(dev_priv))
+		return;
I'd still like to see this getting done uncoditionally. That way we
might get a bit of extra testing for the SCDC helper no matter what
platform the user happens to own.
Sure, seems a good idea. I just added this hear to address the review
comment from Ander.
Also, I can move this IS_GLK condition to compute_config, and once we
check this in compute_config
we might never have check it again.
I thought you already had the check in there? Hmm. Looks that way to me.
Yep, I already have that (this shows I have too many versions of code in
my mind too :P),
what I meant was, we can use some of those state checks here before
enabling/disabling sink side scrambling.
But then I realized it won't be the unconditional stuff you actually
want, so please rub my last comment off :-)
Well I think it should work just fine if you simply pass both into this
function as bools, and then in the disable path we pass explicit 'false'
for both, and in the enable path we just pass config->whatever.
Humm, let me try this.

- Shashank
- Shashank
I presume the spec says the sink will reset these to some default value
on HPD or something like that? But I'm not sure trusting them to get
this right is a good idea because reality often doesn't match the
specs. So the safer option IMO would be always tell the sink exactly
what we want.
Yep, You are correct about the spec too, that it says if there is no
scrambled clock post hpd_out for
100ms, the sink should disable scrambling. But connected modeset
scenarios need our attention, where
for example we are switching mode from, 4k@60 (scrambling reqd) ->
1080@60 (scrambling not reqd).
For such cases too, we have to tell sink to disable scrambling.
+
+	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");
+}
+
    static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
    			     enum port port)
    {
--
1.9.1

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