[PATCH v7 0/2 RESEND] drm: bridge: add ssd2825 RGB/DSI bridge support

[PATCH v7 0/2 RESEND] drm: bridge: add ssd2825 RGB/DSI bridge support

[Svyatoslav Ryhel]

Solomon SSD2825 is a RGB to MIPI DSI bridge used in LG Optimus 4D P880
and LG Optimus Vu P895

---
Changes on switching from v6 to v7:
- removed enabled checks
- configuration complete quirk moved from host_transfer to
  atomic_enable
- switched to devm_drm_bridge_alloc
- removed redundant dev_set_drvdata use

Changes on switching from v5 to v6:
- set correct module name in Kconfig help
- return error if spi sync failed for reading

Changes on switching from v4 to v5:
- rebased on top of drm-misc-next with adjustments to fit

Changes on switching from v3 to v4:
- no changes, resend

Changes on switching from v2 to v3:
- added mutex guard
- configuration register flags parametrized using panel flags
- removed unneded debug messages
- removed unimplemented modes checks
- added check for maximum pixel row length
- use types header
- remove ssd2825_to_ns
- shift bridge setup into atomic pre-enable
- cleaned default values of hzd and hpd

Changes on switching from v1 to v2:
- added description for clock
- removed clock-names
- added boundries for hs-zero-delay-ns and hs-prep-delay-ns
- added mutex lock for host transfers
- converted to atomic ops
- get drm_display_mode mode with atomic helpers
- parameterized INTERFACE_CTRL_REG_6 configuration
- added video mode validation and fixup
- removed clock name
- switched to devm_regulator_bulk_get_const
- added default timings
---

Svyatoslav Ryhel (2):
  dt-bindings: display: bridge: Document Solomon SSD2825
  drm: bridge: Add support for Solomon SSD2825 RGB/DSI bridge

 .../display/bridge/solomon,ssd2825.yaml       | 141 ++++
 drivers/gpu/drm/bridge/Kconfig                |  13 +
 drivers/gpu/drm/bridge/Makefile               |   1 +
 drivers/gpu/drm/bridge/ssd2825.c              | 775 ++++++++++++++++++
 4 files changed, 930 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
 create mode 100644 drivers/gpu/drm/bridge/ssd2825.c

-- 
2.48.1

[PATCH v7 1/2 RESEND] dt-bindings: display: bridge: Document Solomon SSD2825

[Svyatoslav Ryhel]

Add bindings for Solomon SSD2825 MIPI master bridge chip that connects an
application processor with traditional parallel LCD interface and an LCD
driver with MIPI slave interface. The SSD2825 supports both parallel RGB
interface and serial SPI interface.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../display/bridge/solomon,ssd2825.yaml       | 141 ++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml

diff --git a/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml b/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
new file mode 100644
index 000000000000..e2d293d623b8
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bridge/solomon,ssd2825.yaml
@@ -0,0 +1,141 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/solomon,ssd2825.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Solomon SSD2825 RGB to MIPI-DSI bridge
+
+maintainers:
+  - Svyatoslav Ryhel <clamor95@gmail.com>
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: solomon,ssd2825
+
+  reg:
+    maxItems: 1
+
+  reset-gpios: true
+
+  dvdd-supply:
+    description: Regulator for 1.2V digital power supply.
+
+  avdd-supply:
+    description: Regulator for 1.2V analog power supply.
+
+  vddio-supply:
+    description: Regulator for 1.8V IO power supply.
+
+  spi-max-frequency:
+    maximum: 1000000
+
+  spi-cpha: true
+  spi-cpol: true
+
+  clocks:
+    maxItems: 1
+    description: Reference TX_CLK used before PLL is locked.
+
+  solomon,hs-zero-delay-ns:
+    description:
+      HS zero delay period
+    minimum: 0
+    maximum: 1700
+    default: 133
+
+  solomon,hs-prep-delay-ns:
+    description:
+      HS prep delay period
+    minimum: 0
+    maximum: 1728
+    default: 40
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+
+    properties:
+      port@0:
+        $ref: /schemas/graph.yaml#/$defs/port-base
+        unevaluatedProperties: false
+        description:
+          Video port for RGB input
+
+        properties:
+          endpoint:
+            $ref: /schemas/graph.yaml#/$defs/endpoint-base
+            unevaluatedProperties: false
+
+            properties:
+              bus-width:
+                enum: [ 16, 18, 24 ]
+
+      port@1:
+        $ref: /schemas/graph.yaml#/properties/port
+        description:
+          Video port for DSI output (panel or connector)
+
+    required:
+      - port@0
+      - port@1
+
+required:
+  - compatible
+  - ports
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        dsi@2 {
+            compatible = "solomon,ssd2825";
+            reg = <2>;
+
+            spi-max-frequency = <1000000>;
+
+            spi-cpha;
+            spi-cpol;
+
+            reset-gpios = <&gpio 114 GPIO_ACTIVE_LOW>;
+
+            dvdd-supply = <&vdd_1v2>;
+            avdd-supply = <&vdd_1v2>;
+            vddio-supply = <&vdd_1v8_io>;
+
+            solomon,hs-zero-delay-ns = <300>;
+            solomon,hs-prep-delay-ns = <65>;
+
+            clocks = <&ssd2825_tx_clk>;
+
+            ports {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                port@0 {
+                    reg = <0>;
+
+                    bridge_input: endpoint {
+                        remote-endpoint = <&dpi_output>;
+                        bus-width = <24>;
+                    };
+                };
+
+                port@1 {
+                    reg = <1>;
+
+                    bridge_output: endpoint {
+                        remote-endpoint = <&panel_input>;
+                    };
+                };
+            };
+        };
+    };
-- 
2.48.1

[PATCH v7 2/2 RESEND] drm: bridge: Add support for Solomon SSD2825 RGB/DSI bridge

[Svyatoslav Ryhel]

SSD2825 is a cost-effective MIPI Bridge Chip solution targeting mainly
smartphones. It can convert 24bit RGB interface into 4-lane MIPI-DSI
interface to drive display modules of up to 800 x 1366, while supporting
AMOLED, a-si LCD or LTPS panel technologies for smartphone applications.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
---
 drivers/gpu/drm/bridge/Kconfig   |  13 +
 drivers/gpu/drm/bridge/Makefile  |   1 +
 drivers/gpu/drm/bridge/ssd2825.c | 775 +++++++++++++++++++++++++++++++
 3 files changed, 789 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/ssd2825.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index b9e0ca85226a..c11444c80d88 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -316,6 +316,19 @@ config DRM_SIMPLE_BRIDGE
 	  Support for non-programmable DRM bridges, such as ADI ADV7123, TI
 	  THS8134 and THS8135 or passive resistor ladder DACs.
 
+config DRM_SOLOMON_SSD2825
+	tristate "SSD2825 RGB/DSI bridge"
+	depends on SPI_MASTER && OF
+	select DRM_MIPI_DSI
+	select DRM_KMS_HELPER
+	select DRM_PANEL
+	help
+	  Say Y here if you want support for the Solomon SSD2825 RGB/DSI
+	  SPI bridge driver.
+
+	  Say M here if you want to support this hardware as a module.
+	  The module will be named "ssd2825".
+
 config DRM_THINE_THC63LVD1024
 	tristate "Thine THC63LVD1024 LVDS decoder bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 245e8a27e3fc..19f5a09d9291 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_DRM_SIL_SII8620) += sil-sii8620.o
 obj-$(CONFIG_DRM_SII902X) += sii902x.o
 obj-$(CONFIG_DRM_SII9234) += sii9234.o
 obj-$(CONFIG_DRM_SIMPLE_BRIDGE) += simple-bridge.o
+obj-$(CONFIG_DRM_SOLOMON_SSD2825) += ssd2825.o
 obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358762) += tc358762.o
 obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
diff --git a/drivers/gpu/drm/bridge/ssd2825.c b/drivers/gpu/drm/bridge/ssd2825.c
new file mode 100644
index 000000000000..d76dd0dcd38a
--- /dev/null
+++ b/drivers/gpu/drm/bridge/ssd2825.c
@@ -0,0 +1,775 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/units.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_of.h>
+#include <drm/drm_panel.h>
+#include <video/mipi_display.h>
+
+#define SSD2825_DEVICE_ID_REG			0xb0
+#define SSD2825_RGB_INTERFACE_CTRL_REG_1	0xb1
+#define SSD2825_RGB_INTERFACE_CTRL_REG_2	0xb2
+#define SSD2825_RGB_INTERFACE_CTRL_REG_3	0xb3
+#define SSD2825_RGB_INTERFACE_CTRL_REG_4	0xb4
+#define SSD2825_RGB_INTERFACE_CTRL_REG_5	0xb5
+#define SSD2825_RGB_INTERFACE_CTRL_REG_6	0xb6
+#define   SSD2825_NON_BURST_EV			BIT(2)
+#define   SSD2825_BURST				BIT(3)
+#define   SSD2825_PCKL_HIGH			BIT(13)
+#define   SSD2825_HSYNC_HIGH			BIT(14)
+#define   SSD2825_VSYNC_HIGH			BIT(15)
+#define SSD2825_CONFIGURATION_REG		0xb7
+#define   SSD2825_CONF_REG_HS			BIT(0)
+#define   SSD2825_CONF_REG_CKE			BIT(1)
+#define   SSD2825_CONF_REG_SLP			BIT(2)
+#define   SSD2825_CONF_REG_VEN			BIT(3)
+#define   SSD2825_CONF_REG_HCLK			BIT(4)
+#define   SSD2825_CONF_REG_CSS			BIT(5)
+#define   SSD2825_CONF_REG_DCS			BIT(6)
+#define   SSD2825_CONF_REG_REN			BIT(7)
+#define   SSD2825_CONF_REG_ECD			BIT(8)
+#define   SSD2825_CONF_REG_EOT			BIT(9)
+#define   SSD2825_CONF_REG_LPE			BIT(10)
+#define SSD2825_VC_CTRL_REG			0xb8
+#define SSD2825_PLL_CTRL_REG			0xb9
+#define SSD2825_PLL_CONFIGURATION_REG		0xba
+#define SSD2825_CLOCK_CTRL_REG			0xbb
+#define SSD2825_PACKET_SIZE_CTRL_REG_1		0xbc
+#define SSD2825_PACKET_SIZE_CTRL_REG_2		0xbd
+#define SSD2825_PACKET_SIZE_CTRL_REG_3		0xbe
+#define SSD2825_PACKET_DROP_REG			0xbf
+#define SSD2825_OPERATION_CTRL_REG		0xc0
+#define SSD2825_MAX_RETURN_SIZE_REG		0xc1
+#define SSD2825_RETURN_DATA_COUNT_REG		0xc2
+#define SSD2825_ACK_RESPONSE_REG		0xc3
+#define SSD2825_LINE_CTRL_REG			0xc4
+#define SSD2825_INTERRUPT_CTRL_REG		0xc5
+#define SSD2825_INTERRUPT_STATUS_REG		0xc6
+#define SSD2825_ERROR_STATUS_REG		0xc7
+#define SSD2825_DATA_FORMAT_REG			0xc8
+#define SSD2825_DELAY_ADJ_REG_1			0xc9
+#define SSD2825_DELAY_ADJ_REG_2			0xca
+#define SSD2825_DELAY_ADJ_REG_3			0xcb
+#define SSD2825_DELAY_ADJ_REG_4			0xcc
+#define SSD2825_DELAY_ADJ_REG_5			0xcd
+#define SSD2825_DELAY_ADJ_REG_6			0xce
+#define SSD2825_HS_TX_TIMER_REG_1		0xcf
+#define SSD2825_HS_TX_TIMER_REG_2		0xd0
+#define SSD2825_LP_RX_TIMER_REG_1		0xd1
+#define SSD2825_LP_RX_TIMER_REG_2		0xd2
+#define SSD2825_TE_STATUS_REG			0xd3
+#define SSD2825_SPI_READ_REG			0xd4
+#define   SSD2825_SPI_READ_REG_RESET		0xfa
+#define SSD2825_PLL_LOCK_REG			0xd5
+#define SSD2825_TEST_REG			0xd6
+#define SSD2825_TE_COUNT_REG			0xd7
+#define SSD2825_ANALOG_CTRL_REG_1		0xd8
+#define SSD2825_ANALOG_CTRL_REG_2		0xd9
+#define SSD2825_ANALOG_CTRL_REG_3		0xda
+#define SSD2825_ANALOG_CTRL_REG_4		0xdb
+#define SSD2825_INTERRUPT_OUT_CTRL_REG		0xdc
+#define SSD2825_RGB_INTERFACE_CTRL_REG_7	0xdd
+#define SSD2825_LANE_CONFIGURATION_REG		0xde
+#define SSD2825_DELAY_ADJ_REG_7			0xdf
+#define SSD2825_INPUT_PIN_CTRL_REG_1		0xe0
+#define SSD2825_INPUT_PIN_CTRL_REG_2		0xe1
+#define SSD2825_BIDIR_PIN_CTRL_REG_1		0xe2
+#define SSD2825_BIDIR_PIN_CTRL_REG_2		0xe3
+#define SSD2825_BIDIR_PIN_CTRL_REG_3		0xe4
+#define SSD2825_BIDIR_PIN_CTRL_REG_4		0xe5
+#define SSD2825_BIDIR_PIN_CTRL_REG_5		0xe6
+#define SSD2825_BIDIR_PIN_CTRL_REG_6		0xe7
+#define SSD2825_BIDIR_PIN_CTRL_REG_7		0xe8
+#define SSD2825_CABC_BRIGHTNESS_CTRL_REG_1	0xe9
+#define SSD2825_CABC_BRIGHTNESS_CTRL_REG_2	0xea
+#define SSD2825_CABC_BRIGHTNESS_STATUS_REG	0xeb
+#define SSD2825_READ_REG			0xff
+
+#define SSD2825_COM_BYTE			0x00
+#define SSD2825_DAT_BYTE			0x01
+
+#define SSD2828_LP_CLOCK_DIVIDER(n)		(((n) - 1) & 0x3f)
+#define SSD2825_LP_MIN_CLK			5000 /* KHz */
+#define SSD2825_REF_MIN_CLK			2000 /* KHz */
+
+static const struct regulator_bulk_data ssd2825_supplies[] = {
+	{ .supply = "dvdd" },
+	{ .supply = "avdd" },
+	{ .supply = "vddio" },
+};
+
+struct ssd2825_dsi_output {
+	struct mipi_dsi_device *dev;
+	struct drm_panel *panel;
+	struct drm_bridge *bridge;
+};
+
+struct ssd2825_priv {
+	struct spi_device *spi;
+	struct device *dev;
+
+	struct gpio_desc *reset_gpio;
+	struct regulator_bulk_data *supplies;
+
+	struct clk *tx_clk;
+
+	struct mipi_dsi_host dsi_host;
+	struct drm_bridge bridge;
+	struct ssd2825_dsi_output output;
+
+	struct mutex mlock;	/* for host transfer operations */
+
+	u32 pd_lines;		/* number of Parallel Port Input Data Lines */
+	u32 dsi_lanes;		/* number of DSI Lanes */
+
+	/* Parameters for PLL programming */
+	u32 pll_freq_kbps;	/* PLL in kbps */
+	u32 nibble_freq_khz;	/* PLL div by 4 */
+
+	u32 hzd;		/* HS Zero Delay in ns*/
+	u32 hpd;		/* HS Prepare Delay is ns */
+};
+
+static inline struct ssd2825_priv *dsi_host_to_ssd2825(struct mipi_dsi_host *host)
+{
+	return container_of(host, struct ssd2825_priv, dsi_host);
+}
+
+static inline struct ssd2825_priv *bridge_to_ssd2825(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct ssd2825_priv, bridge);
+}
+
+static int ssd2825_write_raw(struct ssd2825_priv *priv, u8 high_byte, u8 low_byte)
+{
+	struct spi_device *spi = priv->spi;
+	u8 tx_buf[2];
+
+	/*
+	 * Low byte is the value, high byte defines type of
+	 * write cycle, 0 for command and 1 for data.
+	 */
+	tx_buf[0] = low_byte;
+	tx_buf[1] = high_byte;
+
+	return spi_write(spi, tx_buf, 2);
+}
+
+static int ssd2825_write_reg(struct ssd2825_priv *priv, u8 reg, u16 command)
+{
+	u8 datal = (command & 0x00FF);
+	u8 datah = (command & 0xFF00) >> 8;
+	int ret;
+
+	/* Command write cycle */
+	ret = ssd2825_write_raw(priv, SSD2825_COM_BYTE, reg);
+	if (ret)
+		return ret;
+
+	/* Data write cycle bits 7-0 */
+	ret = ssd2825_write_raw(priv, SSD2825_DAT_BYTE, datal);
+	if (ret)
+		return ret;
+
+	/* Data write cycle bits 15-8 */
+	ret = ssd2825_write_raw(priv, SSD2825_DAT_BYTE, datah);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ssd2825_write_dsi(struct ssd2825_priv *priv, const u8 *command, int len)
+{
+	int ret, i;
+
+	ret = ssd2825_write_reg(priv, SSD2825_PACKET_SIZE_CTRL_REG_1, len);
+	if (ret)
+		return ret;
+
+	ret = ssd2825_write_raw(priv, SSD2825_COM_BYTE, SSD2825_PACKET_DROP_REG);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < len; i++) {
+		ret = ssd2825_write_raw(priv, SSD2825_DAT_BYTE, command[i]);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int ssd2825_read_raw(struct ssd2825_priv *priv, u8 cmd, u16 *data)
+{
+	struct spi_device *spi = priv->spi;
+	struct spi_message msg;
+	struct spi_transfer xfer[2];
+	u8 tx_buf[2];
+	u8 rx_buf[2];
+	int ret;
+
+	memset(&xfer, 0, sizeof(xfer));
+
+	tx_buf[1] = (cmd & 0xFF00) >> 8;
+	tx_buf[0] = (cmd & 0x00FF);
+
+	xfer[0].tx_buf = tx_buf;
+	xfer[0].bits_per_word = 9;
+	xfer[0].len = 2;
+
+	xfer[1].rx_buf = rx_buf;
+	xfer[1].bits_per_word = 16;
+	xfer[1].len = 2;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer[0], &msg);
+	spi_message_add_tail(&xfer[1], &msg);
+
+	ret = spi_sync(spi, &msg);
+	if (ret) {
+		dev_err(&spi->dev, "ssd2825 read raw failed %d\n", ret);
+		return ret;
+	}
+
+	*data = rx_buf[1] | (rx_buf[0] << 8);
+
+	return 0;
+}
+
+static int ssd2825_read_reg(struct ssd2825_priv *priv, u8 reg, u16 *data)
+{
+	int ret;
+
+	/* Reset the read register */
+	ret = ssd2825_write_reg(priv, SSD2825_SPI_READ_REG, SSD2825_SPI_READ_REG_RESET);
+	if (ret)
+		return ret;
+
+	/* Push the address to read */
+	ret = ssd2825_write_raw(priv, SSD2825_COM_BYTE, reg);
+	if (ret)
+		return ret;
+
+	/* Perform a reading cycle */
+	ret = ssd2825_read_raw(priv, SSD2825_SPI_READ_REG_RESET, data);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ssd2825_dsi_host_attach(struct mipi_dsi_host *host, struct mipi_dsi_device *dev)
+{
+	struct ssd2825_priv *priv = dsi_host_to_ssd2825(host);
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	struct device_node *ep;
+	int ret;
+
+	if (dev->lanes > 4) {
+		dev_err(priv->dev, "unsupported number of data lanes(%u)\n", dev->lanes);
+		return -EINVAL;
+	}
+
+	/*
+	 * ssd2825 supports both Video and Pulse mode, but the driver only
+	 * implements Video (event) mode currently
+	 */
+	if (!(dev->mode_flags & MIPI_DSI_MODE_VIDEO)) {
+		dev_err(priv->dev, "Only MIPI_DSI_MODE_VIDEO is supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	ret = drm_of_find_panel_or_bridge(host->dev->of_node, 1, 0, &panel, &bridge);
+	if (ret)
+		return ret;
+
+	if (panel) {
+		bridge = drm_panel_bridge_add_typed(panel, DRM_MODE_CONNECTOR_DSI);
+		if (IS_ERR(bridge))
+			return PTR_ERR(bridge);
+	}
+
+	priv->output.dev = dev;
+	priv->output.bridge = bridge;
+	priv->output.panel = panel;
+
+	priv->dsi_lanes = dev->lanes;
+
+	/* get input ep (port0/endpoint0) */
+	ret = -EINVAL;
+	ep = of_graph_get_endpoint_by_regs(host->dev->of_node, 0, 0);
+	if (ep) {
+		ret = of_property_read_u32(ep, "bus-width", &priv->pd_lines);
+		of_node_put(ep);
+	}
+
+	if (ret)
+		priv->pd_lines = mipi_dsi_pixel_format_to_bpp(dev->format);
+
+	drm_bridge_add(&priv->bridge);
+
+	return 0;
+}
+
+static int ssd2825_dsi_host_detach(struct mipi_dsi_host *host, struct mipi_dsi_device *dev)
+{
+	struct ssd2825_priv *priv = dsi_host_to_ssd2825(host);
+
+	drm_bridge_remove(&priv->bridge);
+	if (priv->output.panel)
+		drm_panel_bridge_remove(priv->output.bridge);
+
+	return 0;
+}
+
+static ssize_t ssd2825_dsi_host_transfer(struct mipi_dsi_host *host,
+					 const struct mipi_dsi_msg *msg)
+{
+	struct ssd2825_priv *priv = dsi_host_to_ssd2825(host);
+	u16 config;
+	int ret;
+
+	if (msg->rx_len) {
+		dev_warn(priv->dev, "MIPI rx is not supported\n");
+		return -EOPNOTSUPP;
+	}
+
+	guard(mutex)(&priv->mlock);
+
+	ret = ssd2825_read_reg(priv, SSD2825_CONFIGURATION_REG, &config);
+	if (ret)
+		return ret;
+
+	switch (msg->type) {
+	case MIPI_DSI_DCS_SHORT_WRITE:
+	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
+	case MIPI_DSI_DCS_LONG_WRITE:
+		config |= SSD2825_CONF_REG_DCS;
+		break;
+	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
+	case MIPI_DSI_GENERIC_LONG_WRITE:
+		config &= ~SSD2825_CONF_REG_DCS;
+		break;
+	case MIPI_DSI_DCS_READ:
+	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
+	default:
+		return 0;
+	}
+
+	ret = ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+	if (ret)
+		return ret;
+
+	ret = ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0x0000);
+	if (ret)
+		return ret;
+
+	ret = ssd2825_write_dsi(priv, msg->tx_buf, msg->tx_len);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct mipi_dsi_host_ops ssd2825_dsi_host_ops = {
+	.attach = ssd2825_dsi_host_attach,
+	.detach = ssd2825_dsi_host_detach,
+	.transfer = ssd2825_dsi_host_transfer,
+};
+
+static void ssd2825_hw_reset(struct ssd2825_priv *priv)
+{
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	usleep_range(5000, 6000);
+	gpiod_set_value_cansleep(priv->reset_gpio, 0);
+	usleep_range(5000, 6000);
+}
+
+/*
+ * PLL configuration register settings.
+ *
+ * See the "PLL Configuration Register Description" in the SSD2825 datasheet.
+ */
+static u16 construct_pll_config(struct ssd2825_priv *priv,
+				u32 desired_pll_freq_kbps, u32 reference_freq_khz)
+{
+	u32 div_factor = 1, mul_factor, fr = 0;
+
+	while (reference_freq_khz / (div_factor + 1) >= SSD2825_REF_MIN_CLK)
+		div_factor++;
+	if (div_factor > 31)
+		div_factor = 31;
+
+	mul_factor = DIV_ROUND_UP(desired_pll_freq_kbps * div_factor,
+				  reference_freq_khz);
+
+	priv->pll_freq_kbps = reference_freq_khz * mul_factor / div_factor;
+	priv->nibble_freq_khz = priv->pll_freq_kbps / 4;
+
+	if (priv->pll_freq_kbps >= 501000)
+		fr = 3;
+	else if (priv->pll_freq_kbps >= 251000)
+		fr = 2;
+	else if (priv->pll_freq_kbps >= 126000)
+		fr = 1;
+
+	return (fr << 14) | (div_factor << 8) | mul_factor;
+}
+
+static int ssd2825_setup_pll(struct ssd2825_priv *priv,
+			     const struct drm_display_mode *mode)
+{
+	u16 pll_config, lp_div;
+	u32 nibble_delay, pclk_mult, tx_freq_khz;
+	u8 hzd, hpd;
+
+	tx_freq_khz = clk_get_rate(priv->tx_clk) / KILO;
+	if (!tx_freq_khz)
+		tx_freq_khz = SSD2825_REF_MIN_CLK;
+
+	pclk_mult = priv->pd_lines / priv->dsi_lanes + 1;
+	pll_config = construct_pll_config(priv, pclk_mult * mode->clock,
+					  tx_freq_khz);
+
+	lp_div = priv->pll_freq_kbps / (SSD2825_LP_MIN_CLK * 8);
+
+	/* nibble_delay in nanoseconds */
+	nibble_delay = MICRO / priv->nibble_freq_khz;
+
+	hzd = priv->hzd / nibble_delay;
+	hpd = (priv->hpd - 4 * nibble_delay) / nibble_delay;
+
+	/* Disable PLL */
+	ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0000);
+	ssd2825_write_reg(priv, SSD2825_LINE_CTRL_REG, 0x0001);
+
+	/* Set delays */
+	ssd2825_write_reg(priv, SSD2825_DELAY_ADJ_REG_1, (hzd << 8) | hpd);
+
+	/* Set PLL coefficients */
+	ssd2825_write_reg(priv, SSD2825_PLL_CONFIGURATION_REG, pll_config);
+
+	/* Clock Control Register */
+	ssd2825_write_reg(priv, SSD2825_CLOCK_CTRL_REG,
+			  SSD2828_LP_CLOCK_DIVIDER(lp_div));
+
+	/* Enable PLL */
+	ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0001);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	return 0;
+}
+
+static void ssd2825_bridge_atomic_pre_enable(struct drm_bridge *bridge,
+					     struct drm_atomic_state *state)
+{
+	struct ssd2825_priv *priv = bridge_to_ssd2825(bridge);
+	struct mipi_dsi_device *dsi_dev = priv->output.dev;
+	const struct drm_crtc_state *crtc_state;
+	const struct drm_display_mode *mode;
+	struct drm_connector *connector;
+	struct drm_crtc *crtc;
+	u32 input_bus_flags = bridge->timings->input_bus_flags;
+	u16 flags = 0, config;
+	u8 pixel_format;
+	int ret;
+
+	/* Power Sequence */
+	ret = clk_prepare_enable(priv->tx_clk);
+	if (ret)
+		dev_err(priv->dev, "error enabling tx_clk (%d)\n", ret);
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(ssd2825_supplies), priv->supplies);
+	if (ret)
+		dev_err(priv->dev, "error enabling regulators (%d)\n", ret);
+
+	usleep_range(1000, 2000);
+
+	ssd2825_hw_reset(priv);
+
+	/* Perform SW reset */
+	ssd2825_write_reg(priv, SSD2825_OPERATION_CTRL_REG, 0x0100);
+
+	/* Set pixel format */
+	switch (dsi_dev->format) {
+	case MIPI_DSI_FMT_RGB565:
+		pixel_format = 0x00;
+		break;
+	case MIPI_DSI_FMT_RGB666_PACKED:
+		pixel_format = 0x01;
+		break;
+	case MIPI_DSI_FMT_RGB666:
+		pixel_format = 0x02;
+		break;
+	case MIPI_DSI_FMT_RGB888:
+	default:
+		pixel_format = 0x03;
+		break;
+	}
+
+	connector = drm_atomic_get_new_connector_for_encoder(state, bridge->encoder);
+	crtc = drm_atomic_get_new_connector_state(state, connector)->crtc;
+	crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
+	mode = &crtc_state->adjusted_mode;
+
+	/* Set panel timings */
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_1,
+			  ((mode->vtotal - mode->vsync_end) << 8) |
+			  (mode->htotal - mode->hsync_end));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_2,
+			  ((mode->vtotal - mode->vsync_start) << 8) |
+			  (mode->htotal - mode->hsync_start));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_3,
+			  ((mode->vsync_start - mode->vdisplay) << 8) |
+			  (mode->hsync_start - mode->hdisplay));
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_4, mode->hdisplay);
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_5, mode->vdisplay);
+
+	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
+		flags |= SSD2825_HSYNC_HIGH;
+
+	if (mode->flags & DRM_MODE_FLAG_PVSYNC)
+		flags |= SSD2825_VSYNC_HIGH;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_VIDEO)
+		flags |= SSD2825_NON_BURST_EV;
+
+	if (input_bus_flags & DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE)
+		flags |= SSD2825_PCKL_HIGH;
+
+	ssd2825_write_reg(priv, SSD2825_RGB_INTERFACE_CTRL_REG_6, flags | pixel_format);
+	ssd2825_write_reg(priv, SSD2825_LANE_CONFIGURATION_REG, dsi_dev->lanes - 1);
+	ssd2825_write_reg(priv, SSD2825_TEST_REG, 0x0004);
+
+	/* Call PLL configuration */
+	ssd2825_setup_pll(priv, mode);
+
+	usleep_range(10000, 11000);
+
+	config = SSD2825_CONF_REG_HS | SSD2825_CONF_REG_CKE | SSD2825_CONF_REG_DCS |
+		 SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_LPM)
+		config &= ~SSD2825_CONF_REG_HS;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
+		config &= ~SSD2825_CONF_REG_EOT;
+
+	/* Initial DSI configuration register set */
+	ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	if (priv->output.panel)
+		drm_panel_enable(priv->output.panel);
+}
+
+static void ssd2825_bridge_atomic_enable(struct drm_bridge *bridge,
+					 struct drm_atomic_state *state)
+{
+	struct ssd2825_priv *priv = bridge_to_ssd2825(bridge);
+	struct mipi_dsi_device *dsi_dev = priv->output.dev;
+	u16 config;
+
+	config = SSD2825_CONF_REG_HS | SSD2825_CONF_REG_DCS |
+		 SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_VIDEO)
+		config |= SSD2825_CONF_REG_VEN;
+
+	if (dsi_dev->mode_flags & MIPI_DSI_MODE_NO_EOT_PACKET)
+		config &= ~SSD2825_CONF_REG_EOT;
+
+	/* Complete configuration after DSI commands were sent */
+	ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG, config);
+	ssd2825_write_reg(priv, SSD2825_PLL_CTRL_REG, 0x0001);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0x0000);
+}
+
+static void ssd2825_bridge_atomic_disable(struct drm_bridge *bridge,
+					  struct drm_atomic_state *state)
+{
+	struct ssd2825_priv *priv = bridge_to_ssd2825(bridge);
+	int ret;
+
+	msleep(100);
+
+	/* Exit DSI configuration register set */
+	ssd2825_write_reg(priv, SSD2825_CONFIGURATION_REG,
+			  SSD2825_CONF_REG_ECD | SSD2825_CONF_REG_EOT);
+	ssd2825_write_reg(priv, SSD2825_VC_CTRL_REG, 0);
+
+	/* HW disable */
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	usleep_range(5000, 6000);
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(ssd2825_supplies),
+				     priv->supplies);
+	if (ret < 0)
+		dev_err(priv->dev, "error disabling regulators (%d)\n", ret);
+
+	clk_disable_unprepare(priv->tx_clk);
+}
+
+static int ssd2825_bridge_attach(struct drm_bridge *bridge, struct drm_encoder *encoder,
+				 enum drm_bridge_attach_flags flags)
+{
+	struct ssd2825_priv *priv = bridge_to_ssd2825(bridge);
+
+	return drm_bridge_attach(bridge->encoder, priv->output.bridge, bridge,
+				 flags);
+}
+
+static enum drm_mode_status
+ssd2825_bridge_mode_valid(struct drm_bridge *bridge,
+			  const struct drm_display_info *info,
+			  const struct drm_display_mode *mode)
+{
+	if (mode->hdisplay > 1366)
+		return MODE_H_ILLEGAL;
+
+	if (mode->vdisplay > 1366)
+		return MODE_V_ILLEGAL;
+
+	return MODE_OK;
+}
+
+static bool ssd2825_mode_fixup(struct drm_bridge *bridge,
+			       const struct drm_display_mode *mode,
+			       struct drm_display_mode *adjusted_mode)
+{
+	/* Default to positive sync */
+
+	if (!(adjusted_mode->flags &
+	      (DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NHSYNC)))
+		adjusted_mode->flags |= DRM_MODE_FLAG_PHSYNC;
+
+	if (!(adjusted_mode->flags &
+	      (DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_NVSYNC)))
+		adjusted_mode->flags |= DRM_MODE_FLAG_PVSYNC;
+
+	return true;
+}
+
+static const struct drm_bridge_funcs ssd2825_bridge_funcs = {
+	.attach = ssd2825_bridge_attach,
+	.mode_valid = ssd2825_bridge_mode_valid,
+	.mode_fixup = ssd2825_mode_fixup,
+
+	.atomic_pre_enable = ssd2825_bridge_atomic_pre_enable,
+	.atomic_enable = ssd2825_bridge_atomic_enable,
+	.atomic_disable = ssd2825_bridge_atomic_disable,
+
+	.atomic_reset = drm_atomic_helper_bridge_reset,
+	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+};
+
+static const struct drm_bridge_timings default_ssd2825_timings = {
+	.input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE
+		 | DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE
+		 | DRM_BUS_FLAG_DE_HIGH,
+};
+
+static int ssd2825_probe(struct spi_device *spi)
+{
+	struct ssd2825_priv *priv;
+	struct device *dev = &spi->dev;
+	struct device_node *np = dev->of_node;
+	int ret;
+
+	/* Driver supports only 8 bit 3 Wire mode */
+	spi->bits_per_word = 9;
+
+	ret = spi_setup(spi);
+	if (ret)
+		return ret;
+
+	priv = devm_drm_bridge_alloc(dev, struct ssd2825_priv, bridge, &ssd2825_bridge_funcs);
+	if (IS_ERR(priv))
+		return PTR_ERR(priv);
+
+	spi_set_drvdata(spi, priv);
+
+	priv->spi = spi;
+	priv->dev = dev;
+
+	mutex_init(&priv->mlock);
+
+	priv->tx_clk = devm_clk_get_optional(dev, NULL);
+	if (IS_ERR(priv->tx_clk))
+		return dev_err_probe(dev, PTR_ERR(priv->tx_clk),
+				     "can't retrieve bridge tx_clk\n");
+
+	priv->reset_gpio = devm_gpiod_get_optional(dev, "reset",
+						   GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(priv->reset_gpio),
+				     "failed to get reset GPIO\n");
+
+	ret = devm_regulator_bulk_get_const(dev, ARRAY_SIZE(ssd2825_supplies),
+					    ssd2825_supplies, &priv->supplies);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get regulators\n");
+
+	priv->hzd = 133; /* ns */
+	device_property_read_u32(dev, "solomon,hs-zero-delay-ns", &priv->hzd);
+
+	priv->hpd = 40; /* ns */
+	device_property_read_u32(dev, "solomon,hs-prep-delay-ns", &priv->hpd);
+
+	priv->dsi_host.dev = dev;
+	priv->dsi_host.ops = &ssd2825_dsi_host_ops;
+
+	priv->bridge.timings = &default_ssd2825_timings;
+	priv->bridge.of_node = np;
+
+	return mipi_dsi_host_register(&priv->dsi_host);
+}
+
+static void ssd2825_remove(struct spi_device *spi)
+{
+	struct ssd2825_priv *priv = spi_get_drvdata(spi);
+
+	mipi_dsi_host_unregister(&priv->dsi_host);
+}
+
+static const struct of_device_id ssd2825_of_match[] = {
+	{ .compatible = "solomon,ssd2825" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ssd2825_of_match);
+
+static struct spi_driver ssd2825_driver = {
+	.driver = {
+		.name = "ssd2825",
+		.of_match_table = ssd2825_of_match,
+	},
+	.probe = ssd2825_probe,
+	.remove = ssd2825_remove,
+};
+module_spi_driver(ssd2825_driver);
+
+MODULE_AUTHOR("Svyatoslav Ryhel <clamor95@gmail.com>");
+MODULE_DESCRIPTION("Solomon SSD2825 RGB to MIPI-DSI bridge driver SPI");
+MODULE_LICENSE("GPL");
-- 
2.48.1

Re: [PATCH v7 2/2 RESEND] drm: bridge: Add support for Solomon SSD2825 RGB/DSI bridge

[Neil Armstrong]

On 30/07/2025 07:54, Svyatoslav Ryhel wrote:
> SSD2825 is a cost-effective MIPI Bridge Chip solution targeting mainly
> smartphones. It can convert 24bit RGB interface into 4-lane MIPI-DSI
> interface to drive display modules of up to 800 x 1366, while supporting
> AMOLED, a-si LCD or LTPS panel technologies for smartphone applications.
> 
> Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> ---
>   drivers/gpu/drm/bridge/Kconfig   |  13 +
>   drivers/gpu/drm/bridge/Makefile  |   1 +
>   drivers/gpu/drm/bridge/ssd2825.c | 775 +++++++++++++++++++++++++++++++
>   3 files changed, 789 insertions(+)
>   create mode 100644 drivers/gpu/drm/bridge/ssd2825.c
> 

<snip>

LGTM

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Re: [PATCH v7 2/2 RESEND] drm: bridge: Add support for Solomon SSD2825 RGB/DSI bridge

[Dmitry Baryshkov]

On Wed, Jul 30, 2025 at 08:54:24AM +0300, Svyatoslav Ryhel wrote:
> SSD2825 is a cost-effective MIPI Bridge Chip solution targeting mainly
> smartphones. It can convert 24bit RGB interface into 4-lane MIPI-DSI
> interface to drive display modules of up to 800 x 1366, while supporting
> AMOLED, a-si LCD or LTPS panel technologies for smartphone applications.
> 
> Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig   |  13 +
>  drivers/gpu/drm/bridge/Makefile  |   1 +
>  drivers/gpu/drm/bridge/ssd2825.c | 775 +++++++++++++++++++++++++++++++
>  3 files changed, 789 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/ssd2825.c
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v7 0/2 RESEND] drm: bridge: add ssd2825 RGB/DSI bridge support

[Dmitry Baryshkov]

On Wed, 30 Jul 2025 08:54:22 +0300, Svyatoslav Ryhel wrote:
> Solomon SSD2825 is a RGB to MIPI DSI bridge used in LG Optimus 4D P880
> and LG Optimus Vu P895
> 

Applied to drm-misc-next, thanks!

[1/2] dt-bindings: display: bridge: Document Solomon SSD2825
      commit: 784c99331c8d54a51d4f3e772c81f7fb82b7a1f8
[2/2] drm: bridge: Add support for Solomon SSD2825 RGB/DSI bridge
      commit: 55023abe6a2921a8916b623c24208e1971b88729

Best regards,
-- 
With best wishes
Dmitry