drm/i915/dp: Introduce helpers to enable/disable CMN SDP Transmission line

Introduce helpers to program or disable CMN_SDP_TL and stagger registers
using the state stored in crtc_state.

v2:
- Use HAS_COMMON_SDP_TL(display) instead of checking
  crtc_state->dip.cmn_sdp_tl, since 0 is a valid transmission line value.
  (Sashiko)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260915164657.3429075-11-ankit.k.nautiyal@intel.com

2 files changed, 58 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dip.c b/drivers/gpu/drm/i915/display/intel_dip.c
index d1acc7eb5a39..f8e8577b2755 100644
--- a/drivers/gpu/drm/i915/display/intel_dip.c
+++ b/drivers/gpu/drm/i915/display/intel_dip.c
@@ -4,6 +4,8 @@
  *
  */
 
+#include <drm/drm_print.h>
+
 #include "intel_de.h"
 #include "intel_dip.h"
 #include "intel_dip_regs.h"
@@ -61,3 +63,57 @@ void intel_dip_sdp_transmission_line_get_config(struct intel_crtc_state *crtc_st
 {
 	crtc_state->dip.emp_as_sdp_tl = intel_dip_read_emp_as_sdp_tl(crtc_state);
 }
+
+static int intel_dip_sdp_tl_to_stagger(const struct intel_crtc_state *crtc_state,
+				       u16 sdp_transmission_line)
+{
+	return sdp_transmission_line - crtc_state->dip.cmn_sdp_tl;
+}
+
+void intel_dip_cmn_sdp_transmission_line_enable(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
+	int gmp_stagger;
+	int pps_stagger;
+	int vsc_ext_stagger;
+
+	if (!HAS_COMMON_SDP_TL(display))
+		return;
+
+	gmp_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
+						  crtc_state->dip.gmp_sdp_tl);
+
+	pps_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
+						  crtc_state->dip.pps_sdp_tl);
+
+	vsc_ext_stagger = intel_dip_sdp_tl_to_stagger(crtc_state,
+						      crtc_state->dip.vsc_ext_sdp_tl);
+
+	if (drm_WARN_ON(display->drm, gmp_stagger < 0))
+		return;
+	if (drm_WARN_ON(display->drm, pps_stagger < 0))
+		return;
+	if (drm_WARN_ON(display->drm, vsc_ext_stagger < 0))
+		return;
+
+	intel_de_write(display, CMN_SDP_TL_STGR_CTL(display, cpu_transcoder),
+		       GMP_STAGGER(gmp_stagger) |
+		       PPS_STAGGER(pps_stagger) |
+		       VSC_EXT_STAGGER(vsc_ext_stagger));
+
+	intel_de_write(display, CMN_SDP_TL(display, cpu_transcoder),
+		       TRANSMISSION_LINE_ENABLE |
+		       BASE_TRANSMISSION_LINE(crtc_state->dip.cmn_sdp_tl));
+}
+
+void intel_dip_cmn_sdp_transmission_line_disable(const struct intel_crtc_state *old_crtc_state)
+{
+	struct intel_display *display = to_intel_display(old_crtc_state);
+	enum transcoder cpu_transcoder = old_crtc_state->cpu_transcoder;
+
+	if (!HAS_COMMON_SDP_TL(display))
+		return;
+
+	intel_de_write(display, CMN_SDP_TL(display, cpu_transcoder), 0);
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dip.h b/drivers/gpu/drm/i915/display/intel_dip.h
index 8ff22eb5663b..7c64c84cb1be 100644
--- a/drivers/gpu/drm/i915/display/intel_dip.h
+++ b/drivers/gpu/drm/i915/display/intel_dip.h
@@ -47,5 +47,7 @@ void intel_dip_write_emp_as_sdp_tl(const struct intel_crtc_state *crtc_state);
 
 void intel_dip_sdp_tl_compute_config_late(struct intel_crtc_state *crtc_state);
 void intel_dip_sdp_transmission_line_get_config(struct intel_crtc_state *crtc_state);
+void intel_dip_cmn_sdp_transmission_line_enable(const struct intel_crtc_state *crtc_state);
+void intel_dip_cmn_sdp_transmission_line_disable(const struct intel_crtc_state *old_crtc_state);
 
 #endif /* __INTEL_DIP_H__ */