Re: [PATCH V4 09/10] drm/bridge: Add ps8622/ps8625 bridge driver

[Javier Martinez Canillas <javier@dowhile0.org>]

Hello Ajay,

On Wed, Jun 11, 2014 at 8:27 PM, Ajay Kumar <ajaykumar.rs@samsung.com> wrote:
> From: Vincent Palatin <vpalatin@chromium.org>
>
> This patch adds drm_bridge driver for parade DisplayPort
> to LVDS bridge chip.
>
> Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
> Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
> Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
> ---
>  .../devicetree/bindings/drm/bridge/ps8622.txt      |   21 +
>  drivers/gpu/drm/bridge/Kconfig                     |    8 +
>  drivers/gpu/drm/bridge/Makefile                    |    1 +
>  drivers/gpu/drm/bridge/ps8622.c                    |  475 ++++++++++++++++++++
>  include/drm/bridge/ps8622.h                        |   41 ++
>  5 files changed, 546 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/drm/bridge/ps8622.txt
>  create mode 100644 drivers/gpu/drm/bridge/ps8622.c
>  create mode 100644 include/drm/bridge/ps8622.h
>
> diff --git a/Documentation/devicetree/bindings/drm/bridge/ps8622.txt b/Documentation/devicetree/bindings/drm/bridge/ps8622.txt
> new file mode 100644
> index 0000000..1afbd9c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/drm/bridge/ps8622.txt
> @@ -0,0 +1,21 @@
> +ps8622-bridge bindings
> +
> +Required properties:
> +       - compatible: "parade,ps8622"
> +       - reg: first i2c address of the bridge
> +       - sleep-gpio: OF device-tree gpio specification
> +       - reset-gpio: OF device-tree gpio specification
> +
> +Optional properties:
> +       - lane-count: number of DP lanes to use
> +       - use-external-pwm: backlight will be controlled by an external PWM
> +
> +Example:
> +       ps8622-bridge@48 {
> +               compatible = "parade,ps8622";
> +               reg = <0x48>;
> +               sleep-gpio = <&gpc3 6 1 0 0>;
> +               reset-gpio = <&gpc3 1 1 0 0>;
> +               display-timings = <&lcd_display_timings>;
> +               lane-count = <1>
> +       };
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index e3fb487..7b843c8 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -10,3 +10,11 @@ config DRM_PANEL_BINDER
>         select DRM_KMS_HELPER
>         select DRM_PANEL
>         ---help---
> +
> +config DRM_PS8622
> +       tristate "Parade eDP/LVDS bridge"
> +       depends on DRM
> +       select DRM_KMS_HELPER
> +       select BACKLIGHT_LCD_SUPPORT
> +       select BACKLIGHT_CLASS_DEVICE
> +       ---help---
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index ba8b5b8..b494d4b 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -2,3 +2,4 @@ ccflags-y := -Iinclude/drm
>
>  obj-$(CONFIG_DRM_PTN3460) += ptn3460.o
>  obj-$(CONFIG_DRM_PANEL_BINDER) += panel_binder.o
> +obj-$(CONFIG_DRM_PS8622) += ps8622.o
> diff --git a/drivers/gpu/drm/bridge/ps8622.c b/drivers/gpu/drm/bridge/ps8622.c
> new file mode 100644
> index 0000000..387d332
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ps8622.c
> @@ -0,0 +1,475 @@
> +/*
> + * Parade PS8622 eDP/LVDS bridge driver
> + *
> + * Copyright (C) 2014 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/fb.h>
> +#include <linux/gpio.h>
> +#include <linux/i2c.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/pm.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "drmP.h"
> +#include "drm_crtc.h"
> +#include "drm_crtc_helper.h"
> +
> +struct ps8622_bridge {
> +       struct drm_bridge *bridge;
> +       struct drm_encoder *encoder;
> +       struct i2c_client *client;
> +       struct regulator *v12;
> +       struct backlight_device *bl;
> +       struct mutex enable_mutex;
> +
> +       int gpio_slp_n;
> +       int gpio_rst_n;
> +
> +       u8 max_lane_count;
> +       u8 lane_count;
> +
> +       bool enabled;
> +};
> +
> +struct ps8622_device_data {
> +       u8 max_lane_count;
> +};
> +
> +static const struct ps8622_device_data ps8622_data = {
> +       .max_lane_count = 1,
> +};
> +
> +static const struct ps8622_device_data ps8625_data = {
> +       .max_lane_count = 2,
> +};
> +
> +/* Brightness scale on the Parade chip */
> +#define PS8622_MAX_BRIGHTNESS 0xff
> +
> +/* Timings taken from the version 1.7 datasheet for the PS8622/PS8625 */
> +#define PS8622_POWER_RISE_T1_MIN_US 10
> +#define PS8622_POWER_RISE_T1_MAX_US 10000
> +#define PS8622_RST_HIGH_T2_MIN_US 3000
> +#define PS8622_RST_HIGH_T2_MAX_US 30000
> +#define PS8622_PWMO_END_T12_MS 200
> +#define PS8622_POWER_FALL_T16_MAX_US 10000
> +#define PS8622_POWER_OFF_T17_MS 500
> +
> +#if ((PS8622_RST_HIGH_T2_MIN_US + PS8622_POWER_RISE_T1_MAX_US) > \
> +       (PS8622_RST_HIGH_T2_MAX_US + PS8622_POWER_RISE_T1_MIN_US))
> +#error "T2.min + T1.max must be less than T2.max + T1.min"
> +#endif
> +
> +static int ps8622_set(struct i2c_client *client, u8 page, u8 reg, u8 val)
> +{
> +       int ret;
> +       struct i2c_adapter *adap = client->adapter;
> +       struct i2c_msg msg;
> +       u8 data[] = {reg, val};
> +
> +       msg.addr = client->addr + page;
> +       msg.flags = 0;
> +       msg.len = sizeof(data);
> +       msg.buf = data;
> +
> +       ret = i2c_transfer(adap, &msg, 1);
> +       if (ret != 1)
> +               pr_warn("PS8622 I2C write (0x%02x,0x%02x,0x%02x) failed: %d\n",
> +                       client->addr + page, reg, val, ret);
> +       return !(ret == 1);
> +}
> +
> +static int ps8622_send_config(struct ps8622_bridge *ps_bridge)
> +{
> +       struct i2c_client *cl = ps_bridge->client;
> +       int err = 0;
> +
> +       /* wait 20ms after power ON */
> +       usleep_range(20000, 30000);
> +
> +       err |= ps8622_set(cl, 0x02, 0xa1, 0x01); /* HPD low */
> +       /* SW setting */
> +       err |= ps8622_set(cl, 0x04, 0x14, 0x01); /* [1:0] SW output 1.2V voltage
> +                                                 * is lower to 96% */
> +       /* RCO SS setting */
> +       err |= ps8622_set(cl, 0x04, 0xe3, 0x20); /* [5:4] = b01 0.5%, b10 1%,
> +                                                 * b11 1.5% */
> +       err |= ps8622_set(cl, 0x04, 0xe2, 0x80); /* [7] RCO SS enable */
> +       /* RPHY Setting */
> +       err |= ps8622_set(cl, 0x04, 0x8a, 0x0c); /* [3:2] CDR tune wait cycle
> +                                                 * before measure for fine tune
> +                                                 * b00: 1us b01: 0.5us b10:2us
> +                                                 * b11: 4us */
> +       err |= ps8622_set(cl, 0x04, 0x89, 0x08); /* [3] RFD always on */
> +       err |= ps8622_set(cl, 0x04, 0x71, 0x2d); /* CTN lock in/out:
> +                                                 * 20000ppm/80000ppm.
> +                                                 * Lock out 2 times. */
> +       /* 2.7G CDR settings */
> +       err |= ps8622_set(cl, 0x04, 0x7d, 0x07); /* NOF=40LSB for HBR CDR
> +                                                 * setting */
> +       err |= ps8622_set(cl, 0x04, 0x7b, 0x00); /* [1:0] Fmin=+4bands */
> +       err |= ps8622_set(cl, 0x04, 0x7a, 0xfd); /* [7:5] DCO_FTRNG=+-40% */
> +       /* 1.62G CDR settings */
> +       err |= ps8622_set(cl, 0x04, 0xc0, 0x12); /* [5:2]NOF=64LSB [1:0]DCO
> +                                                 * scale is 2/5 */
> +       err |= ps8622_set(cl, 0x04, 0xc1, 0x92); /* Gitune=-37% */
> +       err |= ps8622_set(cl, 0x04, 0xc2, 0x1c); /* Fbstep=100% */
> +       err |= ps8622_set(cl, 0x04, 0x32, 0x80); /* [7] LOS signal disable */
> +       /* RPIO Setting */
> +       err |= ps8622_set(cl, 0x04, 0x00, 0xb0); /* [7:4] LVDS driver bias
> +                                                 * current : 75% (250mV swing)
> +                                                 * */
> +       err |= ps8622_set(cl, 0x04, 0x15, 0x40); /* [7:6] Right-bar GPIO output
> +                                                 * strength is 8mA */
> +       /* EQ Training State Machine Setting */
> +       err |= ps8622_set(cl, 0x04, 0x54, 0x10); /* RCO calibration start */
> +       /* Logic, needs more than 10 I2C command */
> +       err |= ps8622_set(cl, 0x01, 0x02, 0x80 | ps_bridge->max_lane_count);
> +                                                /* [4:0] MAX_LANE_COUNT set to
> +                                                 * max supported lanes */
> +       err |= ps8622_set(cl, 0x01, 0x21, 0x80 | ps_bridge->lane_count);
> +                                                /* [4:0] LANE_COUNT_SET set to
> +                                                 * chosen lane count */
> +       err |= ps8622_set(cl, 0x00, 0x52, 0x20);
> +       err |= ps8622_set(cl, 0x00, 0xf1, 0x03); /* HPD CP toggle enable */
> +       err |= ps8622_set(cl, 0x00, 0x62, 0x41);
> +       err |= ps8622_set(cl, 0x00, 0xf6, 0x01); /* Counter number, add 1ms
> +                                                 * counter delay */
> +       err |= ps8622_set(cl, 0x00, 0x77, 0x06); /* [6]PWM function control by
> +                                                 * DPCD0040f[7], default is PWM
> +                                                 * block always works. */
> +       err |= ps8622_set(cl, 0x00, 0x4c, 0x04); /* 04h Adjust VTotal tolerance
> +                                                 * to fix the 30Hz no display
> +                                                 * issue */
> +       err |= ps8622_set(cl, 0x01, 0xc0, 0x00); /* DPCD00400='h00, Parade OUI =
> +                                                 * 'h001cf8 */
> +       err |= ps8622_set(cl, 0x01, 0xc1, 0x1c); /* DPCD00401='h1c */
> +       err |= ps8622_set(cl, 0x01, 0xc2, 0xf8); /* DPCD00402='hf8 */
> +       err |= ps8622_set(cl, 0x01, 0xc3, 0x44); /* DPCD403~408 = ASCII code
> +                                                 * D2SLV5='h4432534c5635 */
> +       err |= ps8622_set(cl, 0x01, 0xc4, 0x32); /* DPCD404 */
> +       err |= ps8622_set(cl, 0x01, 0xc5, 0x53); /* DPCD405 */
> +       err |= ps8622_set(cl, 0x01, 0xc6, 0x4c); /* DPCD406 */
> +       err |= ps8622_set(cl, 0x01, 0xc7, 0x56); /* DPCD407 */
> +       err |= ps8622_set(cl, 0x01, 0xc8, 0x35); /* DPCD408 */
> +       err |= ps8622_set(cl, 0x01, 0xca, 0x01); /* DPCD40A, Initial Code major
> +                                                 * revision '01' */
> +       err |= ps8622_set(cl, 0x01, 0xcb, 0x05); /* DPCD40B, Initial Code minor
> +                                                 * revision '05' */
> +       if (ps_bridge->bl) {
> +               err |= ps8622_set(cl, 0x01, 0xa5, 0xa0);
> +                                               /* DPCD720, internal PWM */
> +               err |= ps8622_set(cl, 0x01, 0xa7,
> +                               ps_bridge->bl->props.brightness);
> +                                                /* FFh for 100% brightness,
> +                                                 *  0h for 0% brightness */
> +       } else {
> +               err |= ps8622_set(cl, 0x01, 0xa5, 0x80);
> +                                               /* DPCD720, external PWM */
> +       }
> +       err |= ps8622_set(cl, 0x01, 0xcc, 0x13); /* Set LVDS output as 6bit-VESA
> +                                                 * mapping, single LVDS channel
> +                                                 * */
> +       err |= ps8622_set(cl, 0x02, 0xb1, 0x20); /* Enable SSC set by register
> +                                                 * */
> +       err |= ps8622_set(cl, 0x04, 0x10, 0x16); /* Set SSC enabled and +/-1%
> +                                                 * central spreading */
> +       /* Logic end */
> +       err |= ps8622_set(cl, 0x04, 0x59, 0x60); /* MPU Clock source: LC => RCO
> +                                                 * */
> +       err |= ps8622_set(cl, 0x04, 0x54, 0x14); /* LC -> RCO */
> +       err |= ps8622_set(cl, 0x02, 0xa1, 0x91); /* HPD high */
> +
> +       return err ? -EIO : 0;
> +}
> +
> +static int ps8622_backlight_update(struct backlight_device *bl)
> +{
> +       struct ps8622_bridge *ps_bridge = dev_get_drvdata(&bl->dev);
> +       int ret, brightness = bl->props.brightness;
> +
> +       if (bl->props.power != FB_BLANK_UNBLANK ||
> +           bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
> +               brightness = 0;
> +
> +       mutex_lock(&ps_bridge->enable_mutex);
> +
> +       if (!ps_bridge->enabled) {
> +               ret = -EINVAL;
> +               goto out;
> +       }
> +
> +       ret = ps8622_set(ps_bridge->client, 0x01, 0xa7, brightness);
> +
> +out:
> +       mutex_unlock(&ps_bridge->enable_mutex);
> +       return ret;
> +}
> +
> +static int ps8622_backlight_get(struct backlight_device *bl)
> +{
> +       return bl->props.brightness;
> +}
> +
> +static const struct backlight_ops ps8622_backlight_ops = {
> +       .update_status  = ps8622_backlight_update,
> +       .get_brightness = ps8622_backlight_get,
> +};
> +
> +static void ps8622_pre_enable(struct drm_bridge *bridge)
> +{
> +       struct ps8622_bridge *ps_bridge = bridge->driver_private;
> +       int ret;
> +
> +       mutex_lock(&ps_bridge->enable_mutex);
> +       if (ps_bridge->enabled)
> +               goto out;
> +
> +       if (gpio_is_valid(ps_bridge->gpio_rst_n))
> +               gpio_set_value(ps_bridge->gpio_rst_n, 0);
> +
> +       if (ps_bridge->v12) {
> +               ret = regulator_enable(ps_bridge->v12);
> +               if (ret)
> +                       DRM_ERROR("fails to enable ps_bridge->v12");
> +       }
> +
> +       drm_next_bridge_pre_enable(bridge);
> +
> +       if (gpio_is_valid(ps_bridge->gpio_slp_n))
> +               gpio_set_value(ps_bridge->gpio_slp_n, 1);
> +
> +       /*
> +        * T1 is the range of time that it takes for the power to rise after we
> +        * enable the lcd fet. T2 is the range of time in which the data sheet
> +        * specifies we should deassert the reset pin.
> +        *
> +        * If it takes T1.max for the power to rise, we need to wait atleast
> +        * T2.min before deasserting the reset pin. If it takes T1.min for the
> +        * power to rise, we need to wait at most T2.max before deasserting the
> +        * reset pin.
> +        */
> +       usleep_range(PS8622_RST_HIGH_T2_MIN_US + PS8622_POWER_RISE_T1_MAX_US,
> +                    PS8622_RST_HIGH_T2_MAX_US + PS8622_POWER_RISE_T1_MIN_US);
> +
> +       if (gpio_is_valid(ps_bridge->gpio_rst_n))
> +               gpio_set_value(ps_bridge->gpio_rst_n, 1);
> +
> +       ret = ps8622_send_config(ps_bridge);
> +       if (ret)
> +               DRM_ERROR("Failed to send config to bridge (%d)\n", ret);
> +
> +       ps_bridge->enabled = true;
> +
> +out:
> +       mutex_unlock(&ps_bridge->enable_mutex);
> +}
> +
> +static void ps8622_enable(struct drm_bridge *bridge)
> +{
> +       struct ps8622_bridge *ps_bridge = bridge->driver_private;
> +
> +       mutex_lock(&ps_bridge->enable_mutex);
> +       drm_next_bridge_enable(bridge);
> +       mutex_unlock(&ps_bridge->enable_mutex);
> +}
> +
> +static void ps8622_disable(struct drm_bridge *bridge)
> +{
> +       struct ps8622_bridge *ps_bridge = bridge->driver_private;
> +
> +       mutex_lock(&ps_bridge->enable_mutex);
> +
> +       if (!ps_bridge->enabled)
> +               goto out;
> +
> +       ps_bridge->enabled = false;
> +
> +       drm_next_bridge_disable(bridge);
> +       msleep(PS8622_PWMO_END_T12_MS);
> +
> +       /*
> +        * This doesn't matter if the regulators are turned off, but something
> +        * else might keep them on. In that case, we want to assert the slp gpio
> +        * to lower power.
> +        */
> +       if (gpio_is_valid(ps_bridge->gpio_slp_n))
> +               gpio_set_value(ps_bridge->gpio_slp_n, 0);
> +
> +       if (ps_bridge->v12)
> +               regulator_disable(ps_bridge->v12);
> +
> +       /*
> +        * Sleep for at least the amount of time that it takes the power rail to
> +        * fall to prevent asserting the rst gpio from doing anything.
> +        */
> +       usleep_range(PS8622_POWER_FALL_T16_MAX_US,
> +                    2 * PS8622_POWER_FALL_T16_MAX_US);
> +       if (gpio_is_valid(ps_bridge->gpio_rst_n))
> +               gpio_set_value(ps_bridge->gpio_rst_n, 0);
> +
> +       msleep(PS8622_POWER_OFF_T17_MS);
> +
> +out:
> +       mutex_unlock(&ps_bridge->enable_mutex);
> +}
> +
> +static void ps8622_post_disable(struct drm_bridge *bridge)
> +{
> +       drm_next_bridge_post_disable(bridge);
> +}
> +
> +static void ps8622_destroy(struct drm_bridge *bridge)
> +{
> +       struct ps8622_bridge *ps_bridge = bridge->driver_private;
> +
> +       drm_bridge_cleanup(bridge);
> +       if (ps_bridge->bl)
> +               backlight_device_unregister(ps_bridge->bl);
> +
> +       put_device(&ps_bridge->client->dev);
> +}
> +
> +static const struct drm_bridge_funcs ps8622_bridge_funcs = {
> +       .pre_enable = ps8622_pre_enable,
> +       .enable = ps8622_enable,
> +       .disable = ps8622_disable,
> +       .post_disable = ps8622_post_disable,
> +       .destroy = ps8622_destroy,
> +};
> +
> +static const struct of_device_id ps8622_devices[] = {
> +       {
> +               .compatible = "parade,ps8622",
> +               .data   = &ps8622_data,
> +       }, {
> +               .compatible = "parade,ps8625",
> +               .data   = &ps8625_data,
> +       }, {
> +               /* end node */
> +       }
> +};
> +
> +struct drm_bridge *ps8622_init(struct drm_device *dev,
> +                               struct drm_encoder *encoder,
> +                               struct i2c_client *client,
> +                               struct device_node *node)
> +{
> +       int ret;
> +       const struct of_device_id *match;
> +       const struct ps8622_device_data *device_data;
> +       struct drm_bridge *bridge;
> +       struct ps8622_bridge *ps_bridge;
> +
> +       node = of_find_matching_node_and_match(NULL, ps8622_devices, &match);
> +       if (!node)
> +               return NULL;
> +
> +       bridge = devm_kzalloc(dev->dev, sizeof(*bridge), GFP_KERNEL);
> +       if (!bridge) {
> +               DRM_ERROR("Failed to allocate drm bridge\n");
> +               return NULL;
> +       }
> +
> +       ps_bridge = devm_kzalloc(dev->dev, sizeof(*ps_bridge), GFP_KERNEL);
> +       if (!ps_bridge) {
> +               DRM_ERROR("could not allocate ps bridge\n");

It's not necessary to log OOM errors since the mm subsystem already
logs this and calls dump_stack().

> +               return NULL;
> +       }
> +
> +       mutex_init(&ps_bridge->enable_mutex);
> +
> +       device_data = match->data;
> +       ps_bridge->client = client;
> +       ps_bridge->encoder = encoder;
> +       ps_bridge->bridge = bridge;
> +       ps_bridge->v12 = devm_regulator_get(&client->dev, "vdd_bridge");
> +       if (IS_ERR(ps_bridge->v12)) {
> +               DRM_INFO("no 1.2v regulator found for PS8622\n");
> +               ps_bridge->v12 = NULL;
> +       }
> +
> +       ps_bridge->gpio_slp_n = of_get_named_gpio(node, "sleep-gpio", 0);

The new descriptor-based GPIO interface should be used if possible
instead of the deprecated integer-based API.

> +       if (gpio_is_valid(ps_bridge->gpio_slp_n)) {
> +               ret = devm_gpio_request_one(&client->dev, ps_bridge->gpio_slp_n,
> +                                           GPIOF_OUT_INIT_HIGH,
> +                                           "PS8622_SLP_N");
> +               if (ret)
> +                       goto err_client;
> +       }
> +
> +       ps_bridge->gpio_rst_n = of_get_named_gpio(node, "reset-gpio", 0);
> +       if (gpio_is_valid(ps_bridge->gpio_rst_n)) {
> +               /*
> +                * Assert the reset pin high to avoid the bridge being
> +                * initialized prematurely
> +                */
> +               ret = devm_gpio_request_one(&client->dev, ps_bridge->gpio_rst_n,
> +                                           GPIOF_OUT_INIT_HIGH,
> +                                           "PS8622_RST_N");
> +               if (ret)
> +                       goto err_client;
> +       }
> +
> +       ps_bridge->max_lane_count = device_data->max_lane_count;
> +
> +       if (of_property_read_u8(node, "lane-count", &ps_bridge->lane_count))
> +               ps_bridge->lane_count = ps_bridge->max_lane_count;
> +       else if (ps_bridge->lane_count > ps_bridge->max_lane_count) {
> +               DRM_ERROR("lane-count property is too high for DP bridge\n");

DRM_INFO() instead?

> +               ps_bridge->lane_count = ps_bridge->max_lane_count;
> +       }
> +
> +       if (!of_find_property(node, "use-external-pwm", NULL)) {
> +               ps_bridge->bl = backlight_device_register("ps8622-backlight",
> +                               dev->dev, ps_bridge, &ps8622_backlight_ops,
> +                               NULL);
> +               if (IS_ERR(ps_bridge->bl)) {
> +                       DRM_ERROR("failed to register backlight\n");
> +                       ret = PTR_ERR(ps_bridge->bl);
> +                       ps_bridge->bl = NULL;
> +                       goto err_client;
> +               }
> +               ps_bridge->bl->props.max_brightness = PS8622_MAX_BRIGHTNESS;
> +               ps_bridge->bl->props.brightness = PS8622_MAX_BRIGHTNESS;
> +       }
> +
> +       ret = drm_bridge_init(dev, ps_bridge->bridge, &ps8622_bridge_funcs);
> +       if (ret) {
> +               DRM_ERROR("Failed to initialize bridge with drm\n");
> +               goto err_backlight;
> +       }
> +
> +       ps_bridge->bridge->driver_private = ps_bridge;
> +       ps_bridge->enabled = false;
> +
> +       if (!encoder->bridge)
> +               /* First entry in the bridge chain */
> +               encoder->bridge = bridge;
> +
> +       return bridge;
> +
> +err_backlight:
> +       if (ps_bridge->bl)
> +               backlight_device_unregister(ps_bridge->bl);
> +err_client:
> +       put_device(&client->dev);
> +       DRM_ERROR("device probe failed : %d\n", ret);
> +       return NULL;
> +}
> +EXPORT_SYMBOL(ps8622_init);
> diff --git a/include/drm/bridge/ps8622.h b/include/drm/bridge/ps8622.h
> new file mode 100644
> index 0000000..22f37b6
> --- /dev/null
> +++ b/include/drm/bridge/ps8622.h
> @@ -0,0 +1,41 @@
> +/*
> + * Copyright (C) 2014 Google, Inc.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _DRM_BRIDGE_PS8622_H_
> +#define _DRM_BRIDGE_PS8622_H_
> +
> +struct drm_device;
> +struct drm_encoder;
> +struct i2c_client;
> +struct device_node;
> +
> +#ifdef CONFIG_DRM_PS8622
> +
> +struct drm_bridge *ps8622_init(struct drm_device *dev,
> +                               struct drm_encoder *encoder,
> +                               struct i2c_client *client,
> +                               struct device_node *node);
> +
> +#else
> +
> +static inline struct drm_bridge *ps8622_init(struct drm_device *dev,
> +                               struct drm_encoder *encoder,
> +                               struct i2c_client *client,
> +                               struct device_node *node)
> +{
> +       return -ENODEV;
> +}
> +
> +#endif
> +
> +#endif
> --
> 1.7.9.5
>

Best regards,
Javier