[PATCH v4 3/7] drm/rcar-du: dsc: Add rudimentary Renesas R-Car V4H DSC driver
From: Tomi Valkeinen
Date: Mon Jun 15 2026 - 02:29:49 EST
From: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
The Renesas DSC Display Stream Compression is a bridge embedded in the
Renesas R-Car V4H SoC. The bridge performs VESA DSC encoding of up to
8k or 400 Mpixel/s. Add rudimentary driver, which currently acts as a
pass-through bridge and allows DSI1 to be operational on R-Car V4H.
Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
[tomi.valkeinen: use bridge->next_bridge, minor changes]
Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/renesas/rcar-du/Kconfig | 12 +++
drivers/gpu/drm/renesas/rcar-du/Makefile | 1 +
drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c | 149 +++++++++++++++++++++++++++++
3 files changed, 162 insertions(+)
diff --git a/drivers/gpu/drm/renesas/rcar-du/Kconfig b/drivers/gpu/drm/renesas/rcar-du/Kconfig
index 840305fdeb49..80bd770ae0f6 100644
--- a/drivers/gpu/drm/renesas/rcar-du/Kconfig
+++ b/drivers/gpu/drm/renesas/rcar-du/Kconfig
@@ -25,6 +25,18 @@ config DRM_RCAR_CMM
def_tristate DRM_RCAR_DU
depends on DRM_RCAR_USE_CMM
+config DRM_RCAR_USE_DSC
+ bool "R-Car DU DSC Encoder Support"
+ depends on DRM_BRIDGE && OF
+ depends on DRM_RCAR_DU || COMPILE_TEST
+ default DRM_RCAR_DU
+ help
+ Enable support for the R-Car Display Unit embedded DSC encoder.
+
+config DRM_RCAR_DSC
+ def_tristate DRM_RCAR_DU
+ depends on DRM_RCAR_USE_DSC
+
config DRM_RCAR_DW_HDMI
tristate "R-Car Gen3 and RZ/G2 DU HDMI Encoder Support"
depends on DRM && OF
diff --git a/drivers/gpu/drm/renesas/rcar-du/Makefile b/drivers/gpu/drm/renesas/rcar-du/Makefile
index 6f132325c8b7..9ab7a0ac45d8 100644
--- a/drivers/gpu/drm/renesas/rcar-du/Makefile
+++ b/drivers/gpu/drm/renesas/rcar-du/Makefile
@@ -10,6 +10,7 @@ rcar-du-drm-$(CONFIG_DRM_RCAR_VSP) += rcar_du_vsp.o
rcar-du-drm-$(CONFIG_DRM_RCAR_WRITEBACK) += rcar_du_writeback.o
obj-$(CONFIG_DRM_RCAR_CMM) += rcar_cmm.o
+obj-$(CONFIG_DRM_RCAR_DSC) += rcar_dsc.o
obj-$(CONFIG_DRM_RCAR_DU) += rcar-du-drm.o
obj-$(CONFIG_DRM_RCAR_DW_HDMI) += rcar_dw_hdmi.o
obj-$(CONFIG_DRM_RCAR_LVDS) += rcar_lvds.o
diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c b/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c
new file mode 100644
index 000000000000..5a2ff3149136
--- /dev/null
+++ b/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * R-Car DSC Encoder
+ *
+ * Copyright (C) 2025 Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
+ * Copyright (C) 2025 Renesas Electronics Corporation
+ */
+
+#include <linux/container_of.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+
+struct rcar_dsc {
+ struct drm_bridge bridge;
+
+ struct device *dev;
+};
+
+static inline struct rcar_dsc *bridge_to_rcar_dsc(struct drm_bridge *bridge)
+{
+ return container_of(bridge, struct rcar_dsc, bridge);
+}
+
+/* -----------------------------------------------------------------------------
+ * Bridge
+ */
+
+static int rcar_dsc_attach(struct drm_bridge *bridge,
+ struct drm_encoder *encoder,
+ enum drm_bridge_attach_flags flags)
+{
+ struct rcar_dsc *dsc = bridge_to_rcar_dsc(bridge);
+
+ if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
+ return -EINVAL;
+
+ return drm_bridge_attach(encoder, dsc->bridge.next_bridge, bridge,
+ DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+}
+
+static void rcar_dsc_atomic_enable(struct drm_bridge *bridge,
+ struct drm_atomic_commit *commit)
+{
+ struct rcar_dsc *dsc = bridge_to_rcar_dsc(bridge);
+
+ WARN_ON(pm_runtime_get_sync(dsc->dev));
+}
+
+static void rcar_dsc_atomic_disable(struct drm_bridge *bridge,
+ struct drm_atomic_commit *commit)
+{
+ struct rcar_dsc *dsc = bridge_to_rcar_dsc(bridge);
+
+ pm_runtime_put(dsc->dev);
+}
+
+static enum drm_mode_status
+rcar_dsc_bridge_mode_valid(struct drm_bridge *bridge,
+ const struct drm_display_info *info,
+ const struct drm_display_mode *mode)
+{
+ if (mode->hdisplay < 320 || mode->hdisplay > 8190)
+ return MODE_BAD_HVALUE;
+
+ if (mode->vdisplay < 160 || mode->vdisplay > 8190)
+ return MODE_BAD_VVALUE;
+
+ if (mode->clock > 400000) /* Really 400 Mpixel/s */
+ return MODE_CLOCK_HIGH;
+
+ return MODE_OK;
+}
+
+static const struct drm_bridge_funcs rcar_dsc_bridge_ops = {
+ .attach = rcar_dsc_attach,
+ .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+ .atomic_reset = drm_atomic_helper_bridge_reset,
+ .atomic_enable = rcar_dsc_atomic_enable,
+ .atomic_disable = rcar_dsc_atomic_disable,
+ .mode_valid = rcar_dsc_bridge_mode_valid,
+};
+
+/* -----------------------------------------------------------------------------
+ * Probe & Remove
+ */
+
+static int rcar_dsc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rcar_dsc *dsc;
+ int ret;
+
+ dsc = devm_drm_bridge_alloc(dev, struct rcar_dsc, bridge,
+ &rcar_dsc_bridge_ops);
+ if (IS_ERR(dsc))
+ return PTR_ERR(dsc);
+
+ platform_set_drvdata(pdev, dsc);
+
+ dsc->dev = &pdev->dev;
+
+ dsc->bridge.next_bridge = of_drm_get_bridge_by_endpoint(dev->of_node,
+ 1, 0);
+ if (IS_ERR(dsc->bridge.next_bridge))
+ return PTR_ERR(dsc->bridge.next_bridge);
+
+ dsc->bridge.of_node = dev->of_node;
+
+ ret = devm_drm_bridge_add(dev, &dsc->bridge);
+ if (ret)
+ return ret;
+
+ pm_runtime_enable(&pdev->dev);
+
+ return 0;
+}
+
+static void rcar_dsc_remove(struct platform_device *pdev)
+{
+ pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id rcar_dsc_of_table[] = {
+ { .compatible = "renesas,rcar-dsc" },
+ {}
+};
+
+MODULE_DEVICE_TABLE(of, rcar_dsc_of_table);
+
+static struct platform_driver rcar_dsc_platform_driver = {
+ .probe = rcar_dsc_probe,
+ .remove = rcar_dsc_remove,
+ .driver = {
+ .name = "rcar-dsc",
+ .of_match_table = rcar_dsc_of_table,
+ },
+};
+
+module_platform_driver(rcar_dsc_platform_driver);
+
+MODULE_DESCRIPTION("Renesas R-Car DSC Encoder Driver");
+MODULE_LICENSE("GPL");
--
2.43.0