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

Ville Syrjälä
2017-02-22T17:29:54Z

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,
> + 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.

> + 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;
...
}

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

--
Ville Syrjälä
Intel OTC