Statistics is generated from the image frame that is coming to display
and an event is sent to user after reading this histogram data.
v2: forward declaration in header file along with error handling (Jani)
v3: Replaced i915 with intel_display (Suraj)
v4: Removed dithering enable/disable (Vandita)
New patch for histogram register definitions (Suraj)
v5: IET LUT pgm follow the seq in spec and removed change to TC at end
(Suraj)
v8: Retained only the Histogram part and move IET LUT to a different
patch.
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/display/intel_display_types.h | 2 +
drivers/gpu/drm/i915/display/intel_histogram.c | 149 +++++++++++++++++++++
drivers/gpu/drm/i915/display/intel_histogram.h | 48 +++++++
4 files changed, 200 insertions(+)
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 3dda9f0eda82b7501193eb3fb9c0e5dd8efa71e4..8c4277cc63eb6c1e12a1714df2abf07c290aacc6 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -270,6 +270,7 @@ i915-y += \
display/intel_hdcp.o \
display/intel_hdcp_gsc.o \
display/intel_hdcp_gsc_message.o \
+ display/intel_histogram.o \
display/intel_hotplug.o \
display/intel_hotplug_irq.o \
display/intel_hti.o \
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index eb9dd1125a4a09511936b81219e7f38fae106dfd..e17729f0f5f5e9e79a08c9b72ab3772a78e1fbc7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1434,6 +1434,8 @@ struct intel_crtc {
/* for loading single buffered registers during vblank */
struct pm_qos_request vblank_pm_qos;
+ struct intel_histogram *histogram;
+
#ifdef CONFIG_DEBUG_FS
struct intel_pipe_crc pipe_crc;
#endif
diff --git a/drivers/gpu/drm/i915/display/intel_histogram.c b/drivers/gpu/drm/i915/display/intel_histogram.c
new file mode 100644
index 0000000000000000000000000000000000000000..9861252cf3cc9ac5dd68084a6378db36f4cf29ac
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_histogram.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <drm/drm_device.h>
+#include <drm/drm_file.h>
+#include <drm/drm_vblank.h>
+
+#include "i915_reg.h"
+#include "i915_drv.h"
+#include "intel_de.h"
+#include "intel_display.h"
+#include "intel_display_types.h"
+#include "intel_histogram.h"
+#include "intel_histogram_regs.h"
+
+/* 3.0% of the pipe's current pixel count, hw does x4 */
+#define HISTOGRAM_GUARDBAND_THRESHOLD_DEFAULT 300
+/* Precision factor for threshold guardband */
+#define HISTOGRAM_GUARDBAND_PRECISION_FACTOR 10000
+#define HISTOGRAM_DEFAULT_GUARDBAND_DELAY 0x04
+
+int intel_histogram_atomic_check(struct intel_crtc *intel_crtc)
+{
+ struct intel_histogram *histogram = intel_crtc->histogram;
+
+ /* TODO: Restrictions for enabling histogram */
+ histogram->can_enable = true;
+
+ return 0;
+}
+
+static int intel_histogram_enable(struct intel_crtc *intel_crtc, u8 mode)
+{
+ struct intel_display *display = to_intel_display(intel_crtc);
+ struct intel_histogram *histogram = intel_crtc->histogram;
+ int pipe = intel_crtc->pipe;
+ u64 res;
+ u32 gbandthreshold;
+
+ if (!histogram || !histogram->can_enable)
+ return -EINVAL;
+
+ if (histogram->enable)
+ return 0;
+
+ /* enable histogram, clear DPST_CTL bin reg func select to TC */
+ intel_de_rmw(display, DPST_CTL(pipe),
+ DPST_CTL_BIN_REG_FUNC_SEL | DPST_CTL_IE_HIST_EN |
+ DPST_CTL_HIST_MODE | DPST_CTL_IE_TABLE_VALUE_FORMAT |
+ DPST_CTL_ENHANCEMENT_MODE_MASK | DPST_CTL_IE_MODI_TABLE_EN,
+ ((mode == DRM_MODE_HISTOGRAM_HSV_MAX_RGB) ?
+ DPST_CTL_BIN_REG_FUNC_TC : 0) | DPST_CTL_IE_HIST_EN |
+ DPST_CTL_HIST_MODE_HSV |
+ DPST_CTL_IE_TABLE_VALUE_FORMAT_1INT_9FRAC |
+ DPST_CTL_EN_MULTIPLICATIVE | DPST_CTL_IE_MODI_TABLE_EN);
+
+ /* Re-Visit: check if wait for one vblank is required */
+ drm_crtc_wait_one_vblank(&intel_crtc->base);
+
+ /* TODO: Program GuardBand Threshold needs to be moved to modeset path */
+ res = (intel_crtc->config->hw.adjusted_mode.vtotal *
+ intel_crtc->config->hw.adjusted_mode.htotal);
+
+ gbandthreshold = (res * HISTOGRAM_GUARDBAND_THRESHOLD_DEFAULT) /
+ HISTOGRAM_GUARDBAND_PRECISION_FACTOR;
+
+ /* Enable histogram interrupt mode */
+ intel_de_rmw(display, DPST_GUARD(pipe),
+ DPST_GUARD_THRESHOLD_GB_MASK |
+ DPST_GUARD_INTERRUPT_DELAY_MASK | DPST_GUARD_HIST_INT_EN,
+ DPST_GUARD_THRESHOLD_GB(gbandthreshold) |
+ DPST_GUARD_INTERRUPT_DELAY(HISTOGRAM_DEFAULT_GUARDBAND_DELAY) |
+ DPST_GUARD_HIST_INT_EN);
+
+ /* Clear pending interrupts has to be done on separate write */
+ intel_de_rmw(display, DPST_GUARD(pipe),
+ DPST_GUARD_HIST_EVENT_STATUS, 1);
+
+ histogram->enable = true;
+
+ return 0;
+}
+
+static void intel_histogram_disable(struct intel_crtc *intel_crtc)
+{
+ struct intel_display *display = to_intel_display(intel_crtc);
+ struct intel_histogram *histogram = intel_crtc->histogram;
+ int pipe = intel_crtc->pipe;
+
+ if (!histogram)
+ return;
+
+ /* If already disabled return */
+ if (histogram->enable)
+ return;
+
+ /* Clear pending interrupts and disable interrupts */
+ intel_de_rmw(display, DPST_GUARD(pipe),
+ DPST_GUARD_HIST_INT_EN | DPST_GUARD_HIST_EVENT_STATUS, 0);
+
+ /* disable DPST_CTL Histogram mode */
+ intel_de_rmw(display, DPST_CTL(pipe),
+ DPST_CTL_IE_HIST_EN, 0);
+
+ histogram->enable = false;
+}
+
+int intel_histogram_update(struct intel_crtc *intel_crtc,
+ struct drm_histogram_config *config)
+{
+ if (config->enable)
+ return intel_histogram_enable(intel_crtc, config->hist_mode);
+
+ intel_histogram_disable(intel_crtc);
+ return 0;
+}
+
+void intel_histogram_finish(struct intel_crtc *intel_crtc)
+{
+ struct intel_histogram *histogram = intel_crtc->histogram;
+
+ kfree(histogram);
+}
+
+int intel_histogram_init(struct intel_crtc *crtc)
+{
+ struct intel_histogram *histogram;
+ struct drm_histogram_caps *histogram_caps;
+
+ /* Allocate histogram internal struct */
+ histogram = kzalloc(sizeof(*histogram), GFP_KERNEL);
+ if (!histogram)
+ return -ENOMEM;
+ histogram_caps = kzalloc(sizeof(*histogram_caps), GFP_KERNEL);
+ if (!histogram_caps)
+ return -ENOMEM;
+
+ histogram_caps->histogram_mode = DRM_MODE_HISTOGRAM_HSV_MAX_RGB;
+ histogram_caps->bins_count = HISTOGRAM_BIN_COUNT;
+
+ crtc->histogram = histogram;
+ histogram->crtc = crtc;
+ histogram->can_enable = false;
+ histogram->caps = histogram_caps;
+
+ return 0;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_histogram.h b/drivers/gpu/drm/i915/display/intel_histogram.h
new file mode 100644
index 0000000000000000000000000000000000000000..5ea19ef2d3ecadf1ac159a784f51278fdde593de
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_histogram.h
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#ifndef __INTEL_HISTOGRAM_H__
+#define __INTEL_HISTOGRAM_H__
+
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+struct delayed_work;
+struct drm_property_blob;
+struct drm_histogram_config;
+struct drm_histogram_caps;
+struct intel_crtc;
+
+#define HISTOGRAM_BIN_COUNT 32
+
+struct intel_histogram {
+ struct drm_histogram_caps *caps;
+ struct intel_crtc *crtc;
+ struct delayed_work work;
+ bool enable;
+ bool can_enable;
+ u32 bin_data[HISTOGRAM_BIN_COUNT];
+};
+
+enum intel_global_hist_status {
+ INTEL_HISTOGRAM_ENABLE,
+ INTEL_HISTOGRAM_DISABLE,
+};
+
+enum intel_global_histogram {
+ INTEL_HISTOGRAM,
+};
+
+enum intel_global_hist_lut {
+ INTEL_HISTOGRAM_PIXEL_FACTOR,
+};
+
+int intel_histogram_atomic_check(struct intel_crtc *intel_crtc);
+int intel_histogram_update(struct intel_crtc *intel_crtc,
+ struct drm_histogram_config *config);
+int intel_histogram_init(struct intel_crtc *intel_crtc);
+void intel_histogram_finish(struct intel_crtc *intel_crtc);
+
+#endif /* __INTEL_HISTOGRAM_H__ */
--
2.25.1
