[PATCH v4 7/7] drm/i915: Add YCBCR 4:2:0/4:4:4 support for LSPCON

Shashank Sharma
2018-01-30T09:30:54Z

From: "Sharma, Shashank" <shashank.sharma@intel.com>

LSPCON chips can generate YCBCR outputs, if asked nicely :).

In order to generate YCBCR 4:2:0 outputs, a source must:
- send YCBCR 4:4:4 signals to LSPCON
- program color space as 4:2:0 in AVI infoframes

Whereas for YCBCR 4:4:4 outputs, the source must:
- send YCBCR 4:4:4 signals to LSPCON
- program color space as 4:4:4 in AVI infoframes

So for both 4:2:0 as well as 4:4:4 outputs, we are driving the
pipe for YCBCR 4:4:4 output, but AVI infoframe's color space
information indicates LSPCON FW to start scaling down from YCBCR
4:4:4 and generate YCBCR 4:2:0 output. As the scaling is done by
LSPCON device, we need not to reserve a scaler for 4:2:0 outputs.

V2: rebase
V3: Addressed review comments from Ville
- add enum crtc_output_format instead of bool ycbcr420
- use crtc_output_format=4:4:4 for modeset of LSPCON 4:2:0 output
cases in this way we will have YCBCR 4:4:4 framework ready (except
the ABI part)
V4: Added r-b from Maarten (for v3)
Addressed review comments from Ville:
- Do not add a non-atomic state variable to determine lspcon output.
Instead add bool in CRTC state to indicate lspcon based scaling.

Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 2 ++
drivers/gpu/drm/i915/intel_ddi.c | 7 +++++++
drivers/gpu/drm/i915/intel_display.c | 11 ++++++++++-
drivers/gpu/drm/i915/intel_dp.c | 10 ++++++++++
drivers/gpu/drm/i915/intel_drv.h | 5 +++++
drivers/gpu/drm/i915/intel_lspcon.c | 30 ++++++++++++++++++++++++++++++
6 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 64933fd..e383b05 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -8721,6 +8721,8 @@ enum skl_power_gate {
#define TRANS_MSA_MISC(tran) _MMIO_TRANS2(tran, _TRANSA_MSA_MISC)

#define TRANS_MSA_SYNC_CLK (1<<0)
+#define TRANS_MSA_SAMPLING_444 (2<<1)
+#define TRANS_MSA_CLRSP_YCBCR (2<<3)
#define TRANS_MSA_6_BPC (0<<5)
#define TRANS_MSA_8_BPC (1<<5)
#define TRANS_MSA_10_BPC (2<<5)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 510bb77..db7d940 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1499,6 +1499,13 @@ void intel_ddi_set_pipe_settings(const struct intel_crtc_state *crtc_state)
break;
}

+ /*
+ * As per DP 1.2 spec section 2.3.4.3 while sending
+ * YCBCR 444 signals we should program MSA MISC1/0 fields with
+ * colorspace information. The output colorspace encoding is BT601.
+ */
+ if (crtc_state->output_format == CRTC_OUTPUT_YCBCR444)
+ temp |= TRANS_MSA_SAMPLING_444 | TRANS_MSA_CLRSP_YCBCR;
I915_WRITE(TRANS_MSA_MISC(cpu_transcoder), temp);
}

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4a40de9..b26f4a9 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9228,6 +9228,7 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
pipe_config->gamma_mode =
I915_READ(GAMMA_MODE(crtc->pipe)) & GAMMA_MODE_MODE_MASK;

+ pipe_config->external_scaling = false;
if (IS_BROADWELL(dev_priv) || INTEL_GEN(dev_priv) >= 9) {
u32 tmp = I915_READ(PIPEMISC(crtc->pipe));
enum intel_output_format output_format = CRTC_OUTPUT_RGB;
@@ -9247,8 +9248,16 @@ static bool haswell_get_pipe_config(struct intel_crtc *crtc,
output_format = CRTC_OUTPUT_YCBCR420;
} else {
output_format = CRTC_OUTPUT_YCBCR444;
- }

+ /*
+ * As there is no interface defined (yet)
+ * to get the user's preference for output
+ * format, YCBCR444 output format is only
+ * possible with LSPCON YCBCR420 output,
+ * which uses LSPCON's (external )scaler.
+ */
+ pipe_config->external_scaling = true;
+ }
}

pipe_config->output_format = output_format;
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a2e8879..be19579 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1640,6 +1640,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
+ struct intel_lspcon *lspcon = enc_to_intel_lspcon(&encoder->base);
enum port port = encoder->port;
struct intel_crtc *intel_crtc = to_intel_crtc(pipe_config->base.crtc);
struct intel_connector *intel_connector = intel_dp->attached_connector;
@@ -1669,6 +1670,15 @@ intel_dp_compute_config(struct intel_encoder *encoder,
if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv) && port != PORT_A)
pipe_config->has_pch_encoder = true;

+ if (lspcon->active) {
+ struct drm_connector *connector = &intel_connector->base;
+
+ if (lspcon_ycbcr420_config(connector, pipe_config)) {
+ pipe_config->output_format = CRTC_OUTPUT_YCBCR444;
+ pipe_config->external_scaling = true;
+ }
+ }
+
pipe_config->has_drrs = false;
if (IS_G4X(dev_priv) || port == PORT_A)
pipe_config->has_audio = false;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index efaa331..f23129b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -882,6 +882,9 @@ struct intel_crtc_state {

/* Output format RGB/YCBCR etc */
enum intel_output_format output_format;
+
+ /* Output up/down scaling is done in external device */
+ bool external_scaling;
};

struct intel_crtc {
@@ -2139,6 +2142,8 @@ void lspcon_set_infoframes(struct drm_encoder *encoder,
const struct drm_connector_state *conn_state);
bool lspcon_infoframe_enabled(struct drm_encoder *encoder,
const struct intel_crtc_state *pipe_config);
+bool lspcon_ycbcr420_config(struct drm_connector *connector,
+ struct intel_crtc_state *config);

/* intel_pipe_crc.c */
int intel_pipe_crc_create(struct drm_minor *minor);
diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c
index 066ea91..8d6a9b2 100644
--- a/drivers/gpu/drm/i915/intel_lspcon.c
+++ b/drivers/gpu/drm/i915/intel_lspcon.c
@@ -180,6 +180,25 @@ static bool lspcon_wake_native_aux_ch(struct intel_lspcon *lspcon)
return true;
}

+bool lspcon_ycbcr420_config(struct drm_connector *connector,
+ struct intel_crtc_state *config)
+{
+ struct drm_display_info *info = &connector->display_info;
+ struct drm_display_mode *mode = &config->base.adjusted_mode;
+
+ if (drm_mode_is_420_only(info, mode)) {
+ if (!connector->ycbcr_420_allowed) {
+ DRM_ERROR("Platform doesn't support YCBCR420 output\n");
+ return false;
+ }
+
+ config->port_clock /= 2;
+ return true;
+ }
+
+ return false;
+}
+
static bool lspcon_probe(struct intel_lspcon *lspcon)
{
int retry;
@@ -459,6 +478,15 @@ void lspcon_set_infoframes(struct drm_encoder *encoder,
return;
}

+ if (crtc_state->output_format == CRTC_OUTPUT_YCBCR444) {
+ if (crtc_state->external_scaling)
+ frame.avi.colorspace = HDMI_COLORSPACE_YUV420;
+ else
+ frame.avi.colorspace = HDMI_COLORSPACE_YUV444;
+ } else {
+ frame.avi.colorspace = HDMI_COLORSPACE_RGB;
+ }
+
drm_hdmi_avi_infoframe_quant_range(&frame.avi, mode,
crtc_state->limited_color_range ?
HDMI_QUANTIZATION_RANGE_LIMITED :
@@ -512,6 +540,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
struct intel_lspcon *lspcon = &intel_dig_port->lspcon;
struct drm_device *dev = intel_dig_port->base.base.dev;
struct drm_i915_private *dev_priv = to_i915(dev);
+ struct drm_connector *connector = &dp->attached_connector->base;

if (!HAS_LSPCON(dev_priv)) {
DRM_ERROR("LSPCON is not supported on this platform\n");
@@ -536,6 +565,7 @@ bool lspcon_init(struct intel_digital_port *intel_dig_port)
return false;
}

+ connector->ycbcr_420_allowed = true;
lspcon->active = true;
DRM_DEBUG_KMS("Success: LSPCON init\n");
return true;
--
2.7.4