@@ -231,6 +231,7 @@ i915-y += \
display/intel_bo.o \
display/intel_bw.o \
display/intel_cdclk.o \
+ display/intel_cmtg.o \
display/intel_color.o \
display/intel_combo_phy.o \
display/intel_connector.o \
new file mode 100644
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+#include <linux/string_choices.h>
+#include <linux/types.h>
+
+#include <drm/drm_device.h>
+
+#include "i915_reg.h"
+#include "intel_crtc.h"
+#include "intel_cmtg.h"
+#include "intel_cmtg_regs.h"
+#include "intel_de.h"
+#include "intel_display_device.h"
+
+/**
+ * DOC: Common Primary Timing Generator (CMTG)
+ *
+ * The CMTG is a timing generator that runs in parallel to transcoders timing
+ * generators (TG) to provide a synchronization mechanism where CMTG acts as
+ * primary and transcoders TGs act as secondary to the CMTG. The CMTG outputs
+ * its TG start and frame sync signals to the transcoders that are configured
+ * as secondary, which use those signals to synchronize their own timing with
+ * the CMTG's.
+ *
+ * The CMTG can be used only with eDP or MIPI command mode and supports the
+ * following use cases:
+ *
+ * - Dual eDP: The CMTG can be used to keep two eDP TGs in sync when on a
+ * dual eDP configuration (with or without PSR/PSR2 enabled).
+ *
+ * - Single eDP as secondary: It is also possible to use a single eDP
+ * configuration with the transcoder TG as secondary to the CMTG. That would
+ * allow a flow that would not require a modeset on the existing eDP when a
+ * new eDP is added for a dual eDP configuration with CMTG.
+ *
+ * - DC6v: In DC6v, the transcoder might be off but the CMTG keeps running to
+ * maintain frame timings. When exiting DC6v, the transcoder TG then is
+ * synced back the CMTG.
+ *
+ * Currently, the driver does not use the CMTG, but we need to make sure that
+ * we disable it in case we inherit a display configuration with it enabled.
+ */
+
+/*
+ * We describe here only the minimum data required to allow us to properly
+ * disable the CMTG if necessary.
+ */
+struct intel_cmtg_config {
+ bool cmtg_a_enable;
+ /*
+ * Xe2_LPD adds a second CMTG that can be used for dual eDP async mode.
+ */
+ bool cmtg_b_enable;
+ bool trans_a_secondary;
+ bool trans_b_secondary;
+};
+
+static bool intel_cmtg_has_cmtg_b(struct intel_display *display)
+{
+ return DISPLAY_VER(display) >= 20;
+}
+
+static bool intel_cmtg_has_clock_sel(struct intel_display *display)
+{
+ return DISPLAY_VER(display) >= 14;
+}
+
+static void intel_cmtg_dump_config(struct intel_display *display,
+ struct intel_cmtg_config *cmtg_config)
+{
+ drm_dbg_kms(display->drm,
+ "CMTG readout: CMTG A: %s, CMTG B: %s, Transcoder A secondary: %s, Transcoder B secondary: %s\n",
+ str_enabled_disabled(cmtg_config->cmtg_a_enable),
+ intel_cmtg_has_cmtg_b(display) ? str_enabled_disabled(cmtg_config->cmtg_b_enable) : "n/a",
+ str_yes_no(cmtg_config->trans_a_secondary),
+ str_yes_no(cmtg_config->trans_b_secondary));
+}
+
+static void intel_cmtg_get_config(struct intel_display *display,
+ struct intel_cmtg_config *cmtg_config)
+{
+ u32 val;
+
+ if (!HAS_CMTG(display))
+ return;
+
+ val = intel_de_read(display, TRANS_CMTG_CTL_A);
+ cmtg_config->cmtg_a_enable = val & CMTG_ENABLE;
+
+ if (intel_cmtg_has_cmtg_b(display)) {
+ val = intel_de_read(display, TRANS_CMTG_CTL_B);
+ cmtg_config->cmtg_b_enable = val & CMTG_ENABLE;
+ }
+
+ if (intel_crtc_for_pipe(display, PIPE_A)) {
+ val = intel_de_read(display, TRANS_DDI_FUNC_CTL2(display, TRANSCODER_A));
+ cmtg_config->trans_a_secondary = val & CMTG_SECONDARY_MODE;
+ }
+
+ if (intel_crtc_for_pipe(display, PIPE_B)) {
+ val = intel_de_read(display, TRANS_DDI_FUNC_CTL2(display, TRANSCODER_B));
+ cmtg_config->trans_b_secondary = val & CMTG_SECONDARY_MODE;
+ }
+}
+
+static bool intel_cmtg_disable_requires_modeset(struct intel_display *display,
+ struct intel_cmtg_config *cmtg_config)
+{
+ if (DISPLAY_VER(display) >= 20)
+ return false;
+
+ return cmtg_config->trans_a_secondary || cmtg_config->trans_b_secondary;
+}
+
+static void intel_cmtg_disable(struct intel_display *display,
+ struct intel_cmtg_config *cmtg_config)
+{
+ u32 clk_sel_clr = 0;
+ u32 clk_sel_set = 0;
+
+ if (cmtg_config->trans_a_secondary)
+ intel_de_rmw(display, TRANS_DDI_FUNC_CTL2(display, TRANSCODER_A),
+ CMTG_SECONDARY_MODE, 0);
+
+ if (cmtg_config->trans_b_secondary)
+ intel_de_rmw(display, TRANS_DDI_FUNC_CTL2(display, TRANSCODER_B),
+ CMTG_SECONDARY_MODE, 0);
+
+ if (cmtg_config->cmtg_a_enable) {
+ drm_dbg_kms(display->drm, "Disabling CMTG A\n");
+ intel_de_rmw(display, TRANS_CMTG_CTL_A, CMTG_ENABLE, 0);
+ clk_sel_clr |= CMTG_CLK_SEL_A_MASK;
+ clk_sel_set |= CMTG_CLK_SEL_A_DISABLED;
+ }
+
+ if (cmtg_config->cmtg_b_enable) {
+ drm_dbg_kms(display->drm, "Disabling CMTG B\n");
+ intel_de_rmw(display, TRANS_CMTG_CTL_B, CMTG_ENABLE, 0);
+ clk_sel_clr |= CMTG_CLK_SEL_B_MASK;
+ clk_sel_set |= CMTG_CLK_SEL_B_DISABLED;
+ }
+
+ if (intel_cmtg_has_clock_sel(display) && clk_sel_clr)
+ intel_de_rmw(display, CMTG_CLK_SEL, clk_sel_clr, clk_sel_set);
+}
+
+/*
+ * Read out CMTG configuration and, on platforms that allow disabling it without
+ * a modeset, do it.
+ *
+ * This function must be called before any port PLL is disabled in the general
+ * sanitization process, because we need whatever port PLL that is providing the
+ * clock for CMTG to be on before accessing CMTG registers.
+ */
+void intel_cmtg_sanitize(struct intel_display *display)
+{
+ struct intel_cmtg_config cmtg_config = {};
+
+ if (!HAS_CMTG(display))
+ return;
+
+ intel_cmtg_get_config(display, &cmtg_config);
+ intel_cmtg_dump_config(display, &cmtg_config);
+
+ /*
+ * The driver is not prepared to handle cases where a modeset is
+ * required for disabling the CMTG: we need a proper way of tracking
+ * CMTG state and do the right syncronization with respect to triggering
+ * the modeset as part of the disable sequence.
+ */
+ if (drm_WARN_ON(display->drm, intel_cmtg_disable_requires_modeset(display, &cmtg_config)))
+ return;
+
+ intel_cmtg_disable(display, &cmtg_config);
+}
new file mode 100644
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+#ifndef __INTEL_CMTG_H__
+#define __INTEL_CMTG_H__
+
+struct intel_display;
+
+void intel_cmtg_sanitize(struct intel_display *display);
+
+#endif /* __INTEL_CMTG_H__ */
new file mode 100644
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+#ifndef __INTEL_CMTG_REGS_H__
+#define __INTEL_CMTG_REGS_H__
+
+#include "i915_reg_defs.h"
+
+#define CMTG_CLK_SEL _MMIO(0x46160)
+#define CMTG_CLK_SEL_A_MASK REG_GENMASK(31, 29)
+#define CMTG_CLK_SEL_A_DISABLED REG_FIELD_PREP(CMTG_CLK_SEL_A_MASK, 0)
+#define CMTG_CLK_SEL_B_MASK REG_GENMASK(15, 13)
+#define CMTG_CLK_SEL_B_DISABLED REG_FIELD_PREP(CMTG_CLK_SEL_B_MASK, 0)
+
+#define TRANS_CMTG_CTL_A _MMIO(0x6fa88)
+#define TRANS_CMTG_CTL_B _MMIO(0x6fb88)
+#define CMTG_ENABLE REG_BIT(31)
+
+#endif /* __INTEL_CMTG_REGS_H__ */
@@ -146,6 +146,7 @@ struct intel_display_platforms {
#define HAS_BIGJOINER(__display) (DISPLAY_VER(__display) >= 11 && HAS_DSC(__display))
#define HAS_CDCLK_CRAWL(__display) (DISPLAY_INFO(__display)->has_cdclk_crawl)
#define HAS_CDCLK_SQUASH(__display) (DISPLAY_INFO(__display)->has_cdclk_squash)
+#define HAS_CMTG(__display) (!(__display)->platform.dg2 && DISPLAY_VER(__display) >= 13)
#define HAS_CUR_FBC(__display) (!HAS_GMCH(__display) && IS_DISPLAY_VER(__display, 7, 13))
#define HAS_D12_PLANE_MINIMIZATION(__display) ((__display)->platform.rocketlake || (__display)->platform.alderlake_s)
#define HAS_DBUF_OVERLAP_DETECTION(__display) (DISPLAY_RUNTIME_INFO(__display)->has_dbuf_overlap_detection)
@@ -15,6 +15,7 @@
#include "i9xx_wm.h"
#include "intel_atomic.h"
#include "intel_bw.h"
+#include "intel_cmtg.h"
#include "intel_color.h"
#include "intel_crtc.h"
#include "intel_crtc_state_dump.h"
@@ -978,6 +979,8 @@ void intel_modeset_setup_hw_state(struct drm_i915_private *i915,
intel_pch_sanitize(i915);
+ intel_cmtg_sanitize(display);
+
/*
* intel_sanitize_plane_mapping() may need to do vblank
* waits, so we need vblank interrupts restored beforehand.
@@ -3565,6 +3565,7 @@ enum skl_power_gate {
#define _TRANS_DDI_FUNC_CTL2_DSI1 0x6bc04
#define TRANS_DDI_FUNC_CTL2(dev_priv, tran) _MMIO_TRANS2(dev_priv, tran, _TRANS_DDI_FUNC_CTL2_A)
#define PORT_SYNC_MODE_ENABLE REG_BIT(4)
+#define CMTG_SECONDARY_MODE REG_BIT(3)
#define PORT_SYNC_MODE_MASTER_SELECT_MASK REG_GENMASK(2, 0)
#define PORT_SYNC_MODE_MASTER_SELECT(x) REG_FIELD_PREP(PORT_SYNC_MODE_MASTER_SELECT_MASK, (x))
@@ -200,6 +200,7 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
i915-display/intel_bios.o \
i915-display/intel_bw.o \
i915-display/intel_cdclk.o \
+ i915-display/intel_cmtg.o \
i915-display/intel_color.o \
i915-display/intel_combo_phy.o \
i915-display/intel_connector.o \
The CMTG is a timing generator that runs in parallel with transcoders timing generators and can be used as a reference for synchronization. On PTL (display Xe3_LPD), we have observed that we are inheriting from GOP a display configuration with the CMTG enabled. Because our driver doesn't currently implement any CMTG sequences, the CMTG ends up still enabled after our driver takes over. We need to make sure that the CMTG is not enabled if we are not going to use it. For that, let's add a partial implementation in our driver that only cares about disabling the CMTG if it was found enabled during initial hardware readout. In the future, we can also implement sequences for enabling CMTG if that becomes a needed feature. For now, we only deal with cases when it is possible to disable the CMTG without requiring a modeset, which includes Xe3_LPD. For earlier display versions, we add a warning if we find the CMTG enabled and we can't disable it without a proper modeset. v2: - DG2 does not have the CMTG. Update HAS_CMTG() accordingly. - Update logic to force disabling of CMTG only for initial commit. v3: - Add missing changes for v2 that were staged but not committed. v4: - Avoid if/else duplication in intel_cmtg_dump_state() by using "n/a" for CMTG B enabled/disabled string for platforms without it. (Jani) - Prefer intel_cmtg_readout_hw_state() over intel_cmtg_readout_state(). (Jani) - Use display struct instead of i915 as first parameter for TRANS_DDI_FUNC_CTL2(). (Jani) - Fewer continuation lines in variable declaration/initialization for better readability. (Jani) - Coding style improvements. (Jani) - Use drm_dbg_kms() instead of drm_info() for logging the disabling of the CMTG. - Make struct intel_cmtg_state entirely private to intel_cmtg.c. v5: - Do the disable sequence as part of the sanitization step after hardware readout instead of initial modeset commit. (Jani) - Adapt to commit 15133582465f ("drm/i915/display: convert global state to struct intel_display") by using a display struct instead of i915 as argument for intel_atomic_global_obj_init(). v6: - Do not track CMTG state as a global state. (Ville) - Simplify the driver logic by only disabling the CMTG only on cases when a modeset is not required. (Ville) Cc: Jani Nikula <jani.nikula@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com> --- drivers/gpu/drm/i915/Makefile | 1 + drivers/gpu/drm/i915/display/intel_cmtg.c | 178 ++++++++++++++++++ drivers/gpu/drm/i915/display/intel_cmtg.h | 13 ++ .../gpu/drm/i915/display/intel_cmtg_regs.h | 21 +++ .../drm/i915/display/intel_display_device.h | 1 + .../drm/i915/display/intel_modeset_setup.c | 3 + drivers/gpu/drm/i915/i915_reg.h | 1 + drivers/gpu/drm/xe/Makefile | 1 + 8 files changed, 219 insertions(+) create mode 100644 drivers/gpu/drm/i915/display/intel_cmtg.c create mode 100644 drivers/gpu/drm/i915/display/intel_cmtg.h create mode 100644 drivers/gpu/drm/i915/display/intel_cmtg_regs.h