Re: [PATCH v4 2/2] drm/bridge: Introduce LT8912 DSI to HDMI bridge

[Robert Foss]

Hey Adrien,

This looks good to me. All that is missing is DRM_BRIDGE_OP_HPD
support, when that's been implemented I think this series is ready to
be merged.

On Tue, 23 Feb 2021 at 18:56, Adrien Grassein <adrien.grassein@xxxxxxxxx> wrote:
>
> Lontium Lt8912 is a DSI to HDMI bridge.
>
> Signed-off-by: Adrien Grassein <adrien.grassein@xxxxxxxxx>
> ---
>  MAINTAINERS                             |   1 +
>  drivers/gpu/drm/bridge/Kconfig          |  14 +
>  drivers/gpu/drm/bridge/Makefile         |   1 +
>  drivers/gpu/drm/bridge/lontium-lt8912.c | 764 ++++++++++++++++++++++++
>  4 files changed, 780 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/lontium-lt8912.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1e4d49f9dfea..fda331610c35 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10464,6 +10464,7 @@ LONTIUM LT8912 MIPI TO HDMI BRIDGE
>  M:     Adrien Grassein <adrien.grassein@xxxxxxxxx>
>  S:     Maintained
>  F:     Documentation/devicetree/bindings/display/bridge/lontium,lt8912.yaml
> +F:     drivers/gpu/drm/bridge/lontium-lt8912.c
>
>  LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
>  M:     Sathya Prakash <sathya.prakash@xxxxxxxxxxxx>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index e4110d6ca7b3..5b36d4b86e3c 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -48,6 +48,20 @@ config DRM_DISPLAY_CONNECTOR
>           on ARM-based platforms. Saying Y here when this driver is not needed
>           will not cause any issue.
>
> +config DRM_LONTIUM_LT8912
> +       tristate "Lontium LT8912 DSI/HDMI bridge"
> +       depends on OF
> +       select DRM_PANEL_BRIDGE
> +       select DRM_KMS_HELPER
> +       select REGMAP_I2C
> +       help
> +         Driver for Lontium LT8912 DSI to HDMI bridge
> +         chip driver.
> +         Please say Y if you have such hardware.
> +
> +         Say M here if you want to support this hardware as a module.
> +         The module will be named "lontium-lt8912".
> +
>  config DRM_LONTIUM_LT9611
>         tristate "Lontium LT9611 DSI/HDMI bridge"
>         select SND_SOC_HDMI_CODEC if SND_SOC
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 86e7acc76f8d..5a1b201cea1f 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -2,6 +2,7 @@
>  obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
>  obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
>  obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
> +obj-$(CONFIG_DRM_LONTIUM_LT8912) += lontium-lt8912.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912.c b/drivers/gpu/drm/bridge/lontium-lt8912.c
> new file mode 100644
> index 000000000000..11d94da73c37
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912.c
> @@ -0,0 +1,764 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/gpio.h>
> +#include <linux/of_gpio.h>
> +#include <linux/regmap.h>
> +
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +
> +#include <video/videomode.h>
> +
> +#define I2C_MAIN 0
> +#define I2C_ADDR_MAIN 0x48
> +
> +#define I2C_CEC_DSI 1
> +#define I2C_ADDR_CEC_DSI 0x49
> +
> +#define I2C_MAX_IDX 2
> +
> +struct lt8912 {
> +       struct device *dev;
> +       struct drm_bridge bridge;
> +       struct drm_connector connector;
> +
> +       struct i2c_client *i2c_client[I2C_MAX_IDX];
> +       struct regmap *regmap[I2C_MAX_IDX];
> +
> +       struct device_node *host_node;
> +       struct drm_bridge *hdmi_port;
> +
> +       struct mipi_dsi_device *dsi;
> +
> +       struct gpio_desc *gp_reset;
> +
> +       struct videomode mode;
> +
> +       u8 data_lanes;
> +       bool is_power_on;
> +       bool is_attached;
> +};
> +
> +static int lt8912_write_init_config(struct lt8912 *lt)
> +{
> +       const struct reg_sequence seq[] = {
> +               /* Digital clock en*/
> +               {0x08, 0xff},
> +               {0x09, 0xff},
> +               {0x0a, 0xff},
> +               {0x0b, 0x7c},
> +               {0x0c, 0xff},
> +               {0x42, 0x04},
> +
> +               /*Tx Analog*/
> +               {0x31, 0xb1},
> +               {0x32, 0xb1},
> +               {0x33, 0x0e},
> +               {0x37, 0x00},
> +               {0x38, 0x22},
> +               {0x60, 0x82},
> +
> +               /*Cbus Analog*/
> +               {0x39, 0x45},
> +               {0x3a, 0x00},
> +               {0x3b, 0x00},
> +
> +               /*HDMI Pll Analog*/
> +               {0x44, 0x31},
> +               {0x55, 0x44},
> +               {0x57, 0x01},
> +               {0x5a, 0x02},
> +
> +               /*MIPI Analog*/
> +               {0x3e, 0xd6},
> +               {0x3f, 0xd4},
> +               {0x41, 0x3c},
> +               {0xB2, 0x00},
> +       };
> +
> +       return regmap_multi_reg_write(lt->regmap[I2C_MAIN], seq, ARRAY_SIZE(seq));
> +}
> +
> +static int lt8912_write_mipi_basic_config(struct lt8912 *lt)
> +{
> +       const struct reg_sequence seq[] = {
> +               {0x12, 0x04},
> +               {0x14, 0x00},
> +               {0x15, 0x00},
> +               {0x1a, 0x03},
> +               {0x1b, 0x03},
> +       };
> +
> +       return regmap_multi_reg_write(lt->regmap[I2C_CEC_DSI], seq, ARRAY_SIZE(seq));
> +};
> +
> +static int lt8912_write_dds_config(struct lt8912 *lt)
> +{
> +       const struct reg_sequence seq[] = {
> +               {0x4e, 0xff},
> +               {0x4f, 0x56},
> +               {0x50, 0x69},
> +               {0x51, 0x80},
> +               {0x1f, 0x5e},
> +               {0x20, 0x01},
> +               {0x21, 0x2c},
> +               {0x22, 0x01},
> +               {0x23, 0xfa},
> +               {0x24, 0x00},
> +               {0x25, 0xc8},
> +               {0x26, 0x00},
> +               {0x27, 0x5e},
> +               {0x28, 0x01},
> +               {0x29, 0x2c},
> +               {0x2a, 0x01},
> +               {0x2b, 0xfa},
> +               {0x2c, 0x00},
> +               {0x2d, 0xc8},
> +               {0x2e, 0x00},
> +               {0x42, 0x64},
> +               {0x43, 0x00},
> +               {0x44, 0x04},
> +               {0x45, 0x00},
> +               {0x46, 0x59},
> +               {0x47, 0x00},
> +               {0x48, 0xf2},
> +               {0x49, 0x06},
> +               {0x4a, 0x00},
> +               {0x4b, 0x72},
> +               {0x4c, 0x45},
> +               {0x4d, 0x00},
> +               {0x52, 0x08},
> +               {0x53, 0x00},
> +               {0x54, 0xb2},
> +               {0x55, 0x00},
> +               {0x56, 0xe4},
> +               {0x57, 0x0d},
> +               {0x58, 0x00},
> +               {0x59, 0xe4},
> +               {0x5a, 0x8a},
> +               {0x5b, 0x00},
> +               {0x5c, 0x34},
> +               {0x1e, 0x4f},
> +               {0x51, 0x00},
> +       };
> +
> +       return regmap_multi_reg_write(lt->regmap[I2C_CEC_DSI], seq, ARRAY_SIZE(seq));
> +}
> +
> +static int lt8912_write_rxlogicres_config(struct lt8912 *lt)
> +{
> +       int ret;
> +
> +       ret = regmap_write(lt->regmap[I2C_MAIN], 0x03, 0x7f);
> +       usleep_range(10000, 20000);
> +       ret |= regmap_write(lt->regmap[I2C_MAIN], 0x03, 0xff);
> +
> +       return ret;
> +};
> +
> +static int lt8912_write_lvds_config(struct lt8912 *lt)
> +{
> +       const struct reg_sequence seq[] = {
> +               {0x44, 0x30},
> +               {0x51, 0x05},
> +               {0x50, 0x24},
> +               {0x51, 0x2d},
> +               {0x52, 0x04},
> +               {0x69, 0x0e},
> +               {0x69, 0x8e},
> +               {0x6a, 0x00},
> +               {0x6c, 0xb8},
> +               {0x6b, 0x51},
> +               {0x04, 0xfb},
> +               {0x04, 0xff},
> +               {0x7f, 0x00},
> +               {0xa8, 0x13},
> +               {0x02, 0xf7},
> +               {0x02, 0xff},
> +               {0x03, 0xcf},
> +               {0x03, 0xff},
> +       };
> +
> +       return regmap_multi_reg_write(lt->regmap[I2C_CEC_DSI], seq, ARRAY_SIZE(seq));
> +};
> +
> +static inline struct lt8912 *bridge_to_lt8912(struct drm_bridge *b)
> +{
> +       return container_of(b, struct lt8912, bridge);
> +}
> +
> +static inline struct lt8912 *connector_to_lt8912(struct drm_connector *c)
> +{
> +       return container_of(c, struct lt8912, connector);
> +}
> +
> +static const struct regmap_config lt8912_regmap_config = {
> +       .reg_bits = 8,
> +       .val_bits = 8,
> +       .max_register = 0xff,
> +};
> +
> +static int lt8912_init_i2c(struct lt8912 *lt, struct i2c_client *client)
> +{
> +       unsigned int i;
> +       /*
> +        * At this time we only initialize 2 chips, but the lt8912 provides
> +        * a third interface for the audio over HDMI configuration.
> +        */
> +       struct i2c_board_info info[] = {
> +               { I2C_BOARD_INFO("lt8912p0", I2C_ADDR_MAIN), },
> +               { I2C_BOARD_INFO("lt8912p1", I2C_ADDR_CEC_DSI), },
> +       };
> +
> +       if (!lt)
> +               return -ENODEV;
> +
> +       for (i = 0; i < ARRAY_SIZE(info); i++) {
> +               if (i > 0) {
> +                       lt->i2c_client[i] = i2c_new_dummy_device(client->adapter,
> +                                                                info[i].addr);
> +                       if (IS_ERR(lt->i2c_client[i]))
> +                               return PTR_ERR(lt->i2c_client[i]);
> +               }
> +
> +               lt->regmap[i] = devm_regmap_init_i2c(lt->i2c_client[i],
> +                                                    &lt8912_regmap_config);
> +               if (IS_ERR(lt->regmap[i]))
> +                       return PTR_ERR(lt->regmap[i]);
> +       }
> +       return 0;
> +}
> +
> +static int lt8912_free_i2c(struct lt8912 *lt)
> +{
> +       unsigned int i;
> +
> +       for (i = 1; i < I2C_MAX_IDX; i++)
> +               i2c_unregister_device(lt->i2c_client[i]);
> +
> +       return 0;
> +}
> +
> +static int lt8912_hard_power_on(struct lt8912 *lt)
> +{
> +       gpiod_set_value_cansleep(lt->gp_reset, 0);
> +       msleep(20);
> +
> +       return 0;
> +}
> +
> +static void lt8912_hard_power_off(struct lt8912 *lt)
> +{
> +       gpiod_set_value_cansleep(lt->gp_reset, 1);
> +       msleep(20);
> +       lt->is_power_on = false;
> +}
> +
> +static int lt8912_video_setup(struct lt8912 *lt)
> +{
> +       u32 hactive, h_total, hpw, hfp, hbp;
> +       u32 vactive, v_total, vpw, vfp, vbp;
> +       u8 settle = 0x08;
> +       int ret;
> +
> +       if (!lt)
> +               return -EINVAL;
> +
> +       hactive = lt->mode.hactive;
> +       hfp = lt->mode.hfront_porch;
> +       hpw = lt->mode.hsync_len;
> +       hbp = lt->mode.hback_porch;
> +       h_total = hactive + hfp + hpw + hbp;
> +
> +       vactive = lt->mode.vactive;
> +       vfp = lt->mode.vfront_porch;
> +       vpw = lt->mode.vsync_len;
> +       vbp = lt->mode.vback_porch;
> +       v_total = vactive + vfp + vpw + vbp;
> +
> +       if (vactive <= 600)
> +               settle = 0x04;
> +       else if (vactive == 1080)
> +               settle = 0x0a;
> +
> +       ret = regmap_write(lt->regmap[I2C_CEC_DSI], 0x10, 0x01);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x11, settle);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x18, hpw);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x19, vpw);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x1c, hactive & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x1d, hactive >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x2f, 0x0c);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x34, h_total & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x35, h_total >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x36, v_total & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x37, v_total >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x38, vbp & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x39, vbp >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3a, vfp & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3b, vfp >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3c, hbp & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3d, hbp >> 8);
> +
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3e, hfp & 0xff);
> +       ret |= regmap_write(lt->regmap[I2C_CEC_DSI], 0x3f, hfp >> 8);
> +
> +       return ret;
> +}
> +
> +static int lt8912_soft_power_on(struct lt8912 *lt)
> +{
> +       if (!lt->is_power_on) {
> +               u32 lanes = lt->data_lanes;
> +
> +               lt8912_write_init_config(lt);
> +               regmap_write(lt->regmap[I2C_CEC_DSI], 0x13, lanes & 3);
> +
> +               lt8912_write_mipi_basic_config(lt);
> +
> +               lt->is_power_on = true;
> +       }
> +
> +       return 0;
> +}
> +
> +static int lt8912_video_on(struct lt8912 *lt)
> +{
> +       int ret;
> +
> +       ret = lt8912_video_setup(lt);
> +       if (ret < 0)
> +               goto end;
> +
> +       ret = lt8912_write_dds_config(lt);
> +       if (ret < 0)
> +               goto end;
> +
> +       ret = lt8912_write_rxlogicres_config(lt);
> +       if (ret < 0)
> +               goto end;
> +
> +       ret = lt8912_write_lvds_config(lt);
> +       if (ret < 0)
> +               goto end;
> +
> +end:
> +       return ret;
> +}
> +
> +static enum drm_connector_status
> +lt8912_connector_detect(struct drm_connector *connector, bool force)
> +{
> +       struct lt8912 *lt = connector_to_lt8912(connector);
> +
> +       return drm_bridge_detect(lt->hdmi_port);
> +}
> +
> +static const struct drm_connector_funcs lt8912_connector_funcs = {
> +       .detect = lt8912_connector_detect,
> +       .fill_modes = drm_helper_probe_single_connector_modes,
> +       .destroy = drm_connector_cleanup,
> +       .reset = drm_atomic_helper_connector_reset,
> +       .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +       .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static enum drm_mode_status
> +lt8912_connector_mode_valid(struct drm_connector *connector,
> +                           struct drm_display_mode *mode)
> +{
> +       if (mode->clock > 150000)
> +               return MODE_CLOCK_HIGH;
> +
> +       if (mode->hdisplay > 1920)
> +               return MODE_BAD_HVALUE;
> +
> +       if (mode->vdisplay > 1080)
> +               return MODE_BAD_VVALUE;
> +
> +       return MODE_OK;
> +}
> +
> +static int lt8912_connector_get_modes(struct drm_connector *connector)
> +{
> +       struct edid *edid;
> +       int ret, num = 0;
> +       struct lt8912 *lt = connector_to_lt8912(connector);
> +       u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> +
> +       edid = drm_bridge_get_edid(lt->hdmi_port, connector);
> +       if (edid) {
> +               drm_connector_update_edid_property(connector, edid);
> +               num = drm_add_edid_modes(connector, edid);
> +       } else
> +               return ret;
> +
> +       ret = drm_display_info_set_bus_formats(&connector->display_info,
> +                                              &bus_format, 1);
> +       if (ret)
> +               num = ret;
> +
> +       kfree(edid);
> +       return num;
> +}
> +
> +static const struct drm_connector_helper_funcs lt8912_connector_helper_funcs = {
> +       .get_modes = lt8912_connector_get_modes,
> +       .mode_valid = lt8912_connector_mode_valid,
> +};
> +
> +static void lt8912_bridge_mode_set(struct drm_bridge *bridge,
> +                                  const struct drm_display_mode *mode,
> +                                  const struct drm_display_mode *adj)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +
> +       drm_display_mode_to_videomode(adj, &lt->mode);
> +}
> +
> +static void lt8912_bridge_enable(struct drm_bridge *bridge)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +
> +       lt8912_video_on(lt);
> +}
> +
> +static int lt8912_attach_dsi(struct lt8912 *lt)
> +{
> +       struct device *dev = lt->dev;
> +       struct mipi_dsi_host *host;
> +       struct mipi_dsi_device *dsi;
> +       int ret = -1;
> +       const struct mipi_dsi_device_info info = { .type = "lt8912",
> +                                                  .channel = 0,
> +                                                  .node = NULL,
> +                                                };
> +
> +       host = of_find_mipi_dsi_host_by_node(lt->host_node);
> +       if (!host) {
> +               dev_err(dev, "failed to find dsi host\n");
> +               return -EPROBE_DEFER;
> +       }
> +
> +       dsi = mipi_dsi_device_register_full(host, &info);
> +       if (IS_ERR(dsi)) {
> +               ret = PTR_ERR(dsi);
> +               dev_err(dev, "failed to create dsi device (%d)\n", ret);
> +               goto err_dsi_device;
> +       }
> +
> +       lt->dsi = dsi;
> +
> +       dsi->lanes = lt->data_lanes;
> +       dsi->format = MIPI_DSI_FMT_RGB888;
> +
> +       dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
> +                         MIPI_DSI_MODE_VIDEO_BURST |
> +                         MIPI_DSI_MODE_LPM |
> +                         MIPI_DSI_MODE_EOT_PACKET;
> +
> +       ret = mipi_dsi_attach(dsi);
> +       if (ret < 0) {
> +               dev_err(dev, "failed to attach dsi to host\n");
> +               goto err_dsi_attach;
> +       }
> +
> +       return 0;
> +
> +err_dsi_attach:
> +       mipi_dsi_device_unregister(dsi);
> +err_dsi_device:
> +       return ret;
> +}
> +
> +static void lt8912_detach_dsi(struct lt8912 *lt)
> +{
> +       mipi_dsi_detach(lt->dsi);
> +       mipi_dsi_device_unregister(lt->dsi);
> +}
> +
> +static int lt8912_bridge_connector_init(struct drm_bridge *bridge)
> +{
> +       int ret;
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +       struct drm_connector *connector = &lt->connector;
> +
> +       connector->polled = DRM_CONNECTOR_POLL_HPD;
> +
> +       ret = drm_connector_init(bridge->dev, connector,
> +                                &lt8912_connector_funcs,
> +                                lt->hdmi_port->type);
> +       if (ret)
> +               goto exit;
> +
> +       drm_connector_helper_add(connector, &lt8912_connector_helper_funcs);
> +
> +       connector->dpms = DRM_MODE_DPMS_OFF;
> +       drm_connector_attach_encoder(connector, bridge->encoder);
> +exit:
> +       return ret;
> +}
> +
> +static int lt8912_bridge_attach(struct drm_bridge *bridge,
> +                               enum drm_bridge_attach_flags flags)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +       int ret;
> +
> +       if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
> +               ret = lt8912_bridge_connector_init(bridge);
> +               if (ret) {
> +                       dev_err(lt->dev, "Failed to init bridge ! (%d)\n", ret);
> +                       return ret;
> +               }
> +       }
> +
> +
> +       ret = lt8912_hard_power_on(lt);
> +       if (ret)
> +               return ret;
> +
> +       ret = lt8912_soft_power_on(lt);
> +       if (ret)
> +               goto error;
> +
> +       ret = lt8912_attach_dsi(lt);
> +       if (ret)
> +               goto error;
> +
> +       lt->is_attached = true;
> +
> +       return 0;
> +
> +error:
> +       lt8912_hard_power_off(lt);
> +       return ret;
> +}
> +
> +static void lt8912_bridge_detach(struct drm_bridge *bridge)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +
> +       if (lt->is_attached) {
> +               if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
> +                       drm_bridge_hpd_disable(lt->hdmi_port);
> +               lt8912_detach_dsi(lt);
> +               lt8912_hard_power_off(lt);
> +       }
> +}
> +
> +static bool lt8912_cable_is_connected(struct lt8912 *lt)
> +{
> +       int ret;
> +       unsigned int reg_val;
> +
> +       ret = regmap_read(lt->regmap[I2C_MAIN], 0xC1, &reg_val);
> +       if (ret)
> +               return 0;
> +
> +       return (reg_val & BIT(7));
> +}
> +
> +static enum drm_connector_status
> +lt8912_bridge_detect(struct drm_bridge *bridge)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +
> +       if (lt->hdmi_port->ops & DRM_BRIDGE_OP_DETECT)
> +               return drm_bridge_detect(lt->hdmi_port);
> +       else if (lt8912_cable_is_connected(lt))
> +               return connector_status_connected;
> +
> +       return connector_status_disconnected;
> +}
> +
> +static struct edid *lt8912_bridge_get_edid(struct drm_bridge *bridge,
> +                                              struct drm_connector *connector)
> +{
> +       struct lt8912 *lt = bridge_to_lt8912(bridge);
> +
> +       /*
> +        * edid must be read through the ddc bus but it must be
> +        * given to the hdmi connector node.
> +        */
> +       if (lt->hdmi_port->ops & DRM_BRIDGE_OP_EDID)
> +               return drm_bridge_get_edid(lt->hdmi_port, connector);
> +
> +       dev_warn(lt->dev, "The connected bridge does not supports DRM_BRIDGE_OP_EDID\n");
> +       return NULL;
> +}
> +
> +static const struct drm_bridge_funcs lt8912_bridge_funcs = {
> +       .attach = lt8912_bridge_attach,
> +       .detach = lt8912_bridge_detach,
> +       .mode_set = lt8912_bridge_mode_set,
> +       .enable = lt8912_bridge_enable,
> +       .detect = lt8912_bridge_detect,
> +       .get_edid = lt8912_bridge_get_edid,
> +};
> +
> +static int lt8912_parse_dt(struct lt8912 *lt)
> +{
> +       struct gpio_desc *gp_reset;
> +       struct device *dev = lt->dev;
> +       int ret = 0;
> +       struct device_node *port_node;
> +       struct device_node *endpoint;
> +
> +       gp_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> +       if (IS_ERR(gp_reset)) {
> +               ret = PTR_ERR(gp_reset);
> +               if (ret != -EPROBE_DEFER)
> +                       dev_err(dev, "Failed to get reset gpio: %d\n", ret);
> +               return ret;
> +       }
> +       lt->gp_reset = gp_reset;
> +
> +
> +       endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
> +       if (IS_ERR(endpoint)) {
> +               ret = PTR_ERR(endpoint);
> +               goto end;
> +       }
> +
> +       lt->data_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
> +       of_node_put(endpoint);
> +
> +       lt->host_node = of_graph_get_remote_node(dev->of_node, 0, -1);
> +       if (!lt->host_node) {
> +               dev_err(lt->dev, "%s: Failed to get remote port\n", __func__);
> +               ret = -ENODEV;
> +               goto end;
> +       }
> +
> +       port_node = of_graph_get_remote_node(dev->of_node, 1, -1);
> +       if (!port_node) {
> +               dev_err(lt->dev, "%s: Failed to get connector port\n", __func__);
> +               ret = -ENODEV;
> +               goto err_free_host_node;
> +       }
> +
> +       lt->hdmi_port = of_drm_find_bridge(port_node);
> +       if (IS_ERR(lt->hdmi_port)) {
> +               dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
> +               ret = PTR_ERR(lt->hdmi_port);
> +               of_node_put(lt->host_node);
> +               goto end;
> +       }
> +
> +       if (!of_device_is_compatible(port_node, "hdmi-connector")) {
> +               dev_err(lt->dev, "%s: Failed to get hdmi port\n", __func__);
> +               ret = -EINVAL;
> +       }
> +
> +       of_node_put(port_node);
> +
> +end:
> +       return ret;
> +
> +err_free_host_node:
> +       of_node_put(lt->host_node);
> +       return ret;
> +}
> +
> +static int lt8912_put_dt(struct lt8912 *lt)
> +{
> +       of_node_put(lt->host_node);
> +       return 0;
> +}
> +
> +static int lt8912_probe(struct i2c_client *client,
> +        const struct i2c_device_id *id)
> +{
> +       static struct lt8912 *lt;
> +       int ret = 0;
> +       struct device *dev = &client->dev;
> +
> +       lt = devm_kzalloc(dev, sizeof(struct lt8912), GFP_KERNEL);
> +       if (!lt)
> +               return -ENOMEM;
> +
> +       lt->dev = dev;
> +       lt->i2c_client[0] = client;
> +
> +       ret = lt8912_parse_dt(lt);
> +       if (ret)
> +               goto err_dt_parse;
> +
> +       ret = lt8912_init_i2c(lt, client);
> +       if (ret)
> +               goto err_i2c;
> +
> +       i2c_set_clientdata(client, lt);
> +
> +       lt->bridge.funcs = &lt8912_bridge_funcs;
> +       lt->bridge.of_node = dev->of_node;
> +       /*
> +        * Here we don't advertise DRM_BRIDGE_OP_HPD because HPD is not
> +        * working yet.
> +        */
> +       lt->bridge.ops = (DRM_BRIDGE_OP_EDID |
> +                         DRM_BRIDGE_OP_DETECT);
> +
> +       drm_bridge_add(&lt->bridge);
> +
> +       return 0;
> +
> +err_i2c:
> +       lt8912_put_dt(lt);
> +err_dt_parse:
> +       return ret;
> +}
> +
> +static int lt8912_remove(struct i2c_client *client)
> +{
> +       struct lt8912 *lt = i2c_get_clientdata(client);
> +
> +       lt8912_bridge_detach(&lt->bridge);
> +       drm_bridge_remove(&lt->bridge);
> +       lt8912_free_i2c(lt);
> +       lt8912_put_dt(lt);
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id lt8912_dt_match[] = {
> +       {.compatible = "lontium,lt8912"},
> +       {}
> +};
> +MODULE_DEVICE_TABLE(of, lt8912_dt_match);
> +
> +static const struct i2c_device_id lt8912_id[] = {
> +       {"lt8912", 0},
> +       {},
> +};
> +MODULE_DEVICE_TABLE(i2c, lt8912_id);
> +
> +static struct i2c_driver lt8912_i2c_driver = {
> +       .driver = {
> +               .name = "lt8912",
> +               .of_match_table = lt8912_dt_match,
> +               .owner = THIS_MODULE,
> +       },
> +       .probe = lt8912_probe,
> +       .remove = lt8912_remove,
> +       .id_table = lt8912_id,
> +};
> +module_i2c_driver(lt8912_i2c_driver);
> +
> +MODULE_AUTHOR("Adrien Grassein <adrien.grassein@xxxxxxxxx>");
> +MODULE_DESCRIPTION("lt8912 drm driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.25.1
>