Re: [PATCH 3/5] drm/bridge: Add PTN3460 bridge driver

From: Inki Dae
Date: Thu Oct 03 2013 - 09:55:40 EST

Hi, thank you for your contribution and the below is my short comments,

2013/10/2 Sean Paul <seanpaul@xxxxxxxxxxxx>:
> This patch adds a drm_bridge driver for the PTN3460 DisplayPort to LVDS
> bridge chip.
>
> Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> ---
> .../devicetree/bindings/drm/bridge/ptn3460.txt | 27 ++
> drivers/gpu/drm/Kconfig | 2 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/bridge/Kconfig | 4 +
> drivers/gpu/drm/bridge/Makefile | 3 +
> drivers/gpu/drm/bridge/ptn3460.c | 349 +++++++++++++++++++++
> include/drm/bridge/ptn3460.h | 36 +++
> 7 files changed, 422 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/drm/bridge/ptn3460.txt
> create mode 100644 drivers/gpu/drm/bridge/Kconfig
> create mode 100644 drivers/gpu/drm/bridge/Makefile
> create mode 100644 drivers/gpu/drm/bridge/ptn3460.c
> create mode 100644 include/drm/bridge/ptn3460.h
>
> diff --git a/Documentation/devicetree/bindings/drm/bridge/ptn3460.txt b/Documentation/devicetree/bindings/drm/bridge/ptn3460.txt
> new file mode 100644
> index 0000000..c1cd329
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/drm/bridge/ptn3460.txt
> @@ -0,0 +1,27 @@
> +ptn3460-bridge bindings
> +
> +Required properties:
> + - compatible: "nxp,ptn3460"
> + - reg: i2c address of the bridge
> + - powerdown-gpio: OF device-tree gpio specification

Can a regulator be used instead of gpio in other board case?

> + - reset-gpio: OF device-tree gpio specification
> + - edid-emulation: The EDID emulation entry to use
> + +-------+------------+------------------+
> + | Value | Resolution | Description |
> + | 0 | 1024x768 | NXP Generic |
> + | 1 | 1920x1080 | NXP Generic |
> + | 2 | 1920x1080 | NXP Generic |
> + | 3 | 1600x900 | Samsung LTM200KT |
> + | 4 | 1920x1080 | Samsung LTM230HT |
> + | 5 | 1366x768 | NXP Generic |
> + | 6 | 1600x900 | ChiMei M215HGE |
> + +-------+------------+------------------+
> +
> +Example:
> + ptn3460-bridge@20 {
> + compatible = "nxp,ptn3460";
> + reg = <0x20>;
> + powerdown-gpio = <&gpy2 5 1 0 0>;
> + reset-gpio = <&gpx1 5 1 0 0>;
> + edid-emulation = <5>;
> + };
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 955555d..cd7bfb3 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -236,3 +236,5 @@ source "drivers/gpu/drm/tilcdc/Kconfig"
> source "drivers/gpu/drm/qxl/Kconfig"
>
> source "drivers/gpu/drm/msm/Kconfig"
> +
> +source "drivers/gpu/drm/bridge/Kconfig"
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index f089adf..9234253 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -56,3 +56,4 @@ obj-$(CONFIG_DRM_TILCDC) += tilcdc/
> obj-$(CONFIG_DRM_QXL) += qxl/
> obj-$(CONFIG_DRM_MSM) += msm/
> obj-y += i2c/
> +obj-y += bridge/
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> new file mode 100644
> index 0000000..f8db069
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -0,0 +1,4 @@
> +config DRM_PTN3460
> + tristate "PTN3460 DP/LVDS bridge"
> + depends on DRM && I2C
> + ---help---
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> new file mode 100644
> index 0000000..b4733e1
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -0,0 +1,3 @@
> +ccflags-y := -Iinclude/drm
> +
> +obj-$(CONFIG_DRM_PTN3460) += ptn3460.o
> diff --git a/drivers/gpu/drm/bridge/ptn3460.c b/drivers/gpu/drm/bridge/ptn3460.c
> new file mode 100644
> index 0000000..a9e5c1a
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ptn3460.c
> @@ -0,0 +1,349 @@
> +/*
> + * NXP PTN3460 DP/LVDS bridge driver
> + *
> + * Copyright (C) 2013 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/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/i2c.h>
> +#include <linux/gpio.h>
> +#include <linux/delay.h>
> +
> +#include "drmP.h"
> +#include "drm_edid.h"
> +#include "drm_crtc.h"
> +#include "drm_crtc_helper.h"
> +
> +#include "bridge/ptn3460.h"
> +
> +#define PTN3460_EDID_ADDR 0x0
> +#define PTN3460_EDID_EMULATION_ADDR 0x84
> +#define PTN3460_EDID_ENABLE_EMULATION 0
> +#define PTN3460_EDID_EMULATION_SELECTION 1
> +#define PTN3460_EDID_SRAM_LOAD_ADDR 0x85
> +
> +struct ptn3460_bridge {
> + struct drm_connector connector;
> + struct i2c_client *client;
> + struct drm_encoder *encoder;
> + struct drm_bridge *bridge;
> + struct edid *edid;
> + int gpio_pd_n;
> + int gpio_rst_n;
> + u32 edid_emulation;
> + bool enabled;
> +};
> +
> +static int ptn3460_read_bytes(struct ptn3460_bridge *ptn_bridge, char addr,
> + u8 *buf, int len)
> +{
> + int ret;
> +
> + ret = i2c_master_send(ptn_bridge->client, &addr, 1);
> + if (ret <= 0) {
> + DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
> + return ret;
> + }
> +
> + ret = i2c_master_recv(ptn_bridge->client, buf, len);
> + if (ret <= 0) {
> + DRM_ERROR("Failed to recv i2c data, ret=%d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int ptn3460_write_byte(struct ptn3460_bridge *ptn_bridge, char addr,
> + char val)
> +{
> + int ret;
> + char buf[2];
> +
> + buf[0] = addr;
> + buf[1] = val;
> +
> + ret = i2c_master_send(ptn_bridge->client, buf, ARRAY_SIZE(buf));
> + if (ret <= 0) {
> + DRM_ERROR("Failed to send i2c command, ret=%d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int ptn3460_select_edid(struct ptn3460_bridge *ptn_bridge)
> +{
> + int ret;
> + char val;
> +
> + /* Load the selected edid into SRAM (accessed at PTN3460_EDID_ADDR) */
> + ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_SRAM_LOAD_ADDR,
> + ptn_bridge->edid_emulation);
> + if (ret) {
> + DRM_ERROR("Failed to transfer edid to sram, ret=%d\n", ret);
> + return ret;
> + }
> +
> + /* Enable EDID emulation and select the desired EDID */
> + val = 1 << PTN3460_EDID_ENABLE_EMULATION |
> + ptn_bridge->edid_emulation << PTN3460_EDID_EMULATION_SELECTION;
> +
> + ret = ptn3460_write_byte(ptn_bridge, PTN3460_EDID_EMULATION_ADDR, val);
> + if (ret) {
> + DRM_ERROR("Failed to write edid value, ret=%d\n", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static void ptn3460_pre_enable(struct drm_bridge *bridge)
> +{
> + struct ptn3460_bridge *ptn_bridge = bridge->driver_private;
> + int ret;
> +
> + if (ptn_bridge->enabled)
> + return;
> +
> + if (gpio_is_valid(ptn_bridge->gpio_pd_n))
> + gpio_set_value(ptn_bridge->gpio_pd_n, 1);

Ditto.

> +
> + if (gpio_is_valid(ptn_bridge->gpio_rst_n)) {
> + gpio_set_value(ptn_bridge->gpio_rst_n, 0);
> + udelay(10);
> + gpio_set_value(ptn_bridge->gpio_rst_n, 1);
> + }
> +
> + /*
> + * There's a bug in the PTN chip where it falsely asserts hotplug before
> + * it is fully functional. We're forced to wait for the maximum start up
> + * time specified in the chip's datasheet to make sure we're really up.
> + */
> + msleep(90);
> +
> + ret = ptn3460_select_edid(ptn_bridge);
> + if (ret)
> + DRM_ERROR("Select edid failed ret=%d\n", ret);
> +
> + ptn_bridge->enabled = true;
> +}
> +
> +static void ptn3460_enable(struct drm_bridge *bridge)
> +{
> +}
> +
> +static void ptn3460_disable(struct drm_bridge *bridge)
> +{
> + struct ptn3460_bridge *ptn_bridge = bridge->driver_private;
> +
> + if (!ptn_bridge->enabled)
> + return;
> +
> + ptn_bridge->enabled = false;
> +
> + if (gpio_is_valid(ptn_bridge->gpio_rst_n))
> + gpio_set_value(ptn_bridge->gpio_rst_n, 1);
> +
> + if (gpio_is_valid(ptn_bridge->gpio_pd_n))
> + gpio_set_value(ptn_bridge->gpio_pd_n, 0);

Ditto.

> +}
> +
> +static void ptn3460_post_disable(struct drm_bridge *bridge)
> +{
> +}
> +
> +void ptn3460_bridge_destroy(struct drm_bridge *bridge)
> +{
> + struct ptn3460_bridge *ptn_bridge = bridge->driver_private;
> +
> + drm_bridge_cleanup(bridge);
> + if (gpio_is_valid(ptn_bridge->gpio_pd_n))
> + gpio_free(ptn_bridge->gpio_pd_n);

Ditto.

> + if (gpio_is_valid(ptn_bridge->gpio_rst_n))
> + gpio_free(ptn_bridge->gpio_rst_n);
> + /* Nothing else to free, we've got devm allocated memory */
> +}
> +
> +struct drm_bridge_funcs ptn3460_bridge_funcs = {
> + .pre_enable = ptn3460_pre_enable,
> + .enable = ptn3460_enable,
> + .disable = ptn3460_disable,
> + .post_disable = ptn3460_post_disable,
> + .destroy = ptn3460_bridge_destroy,
> +};
> +
> +int ptn3460_get_modes(struct drm_connector *connector)
> +{
> + struct ptn3460_bridge *ptn_bridge;
> + u8 *edid;
> + int ret, num_modes;
> + bool power_off;
> +
> + ptn_bridge = container_of(connector, struct ptn3460_bridge, connector);
> +
> + if (ptn_bridge->edid)
> + return drm_add_edid_modes(connector, ptn_bridge->edid);
> +
> + power_off = !ptn_bridge->enabled;
> + ptn3460_pre_enable(ptn_bridge->bridge);
> +
> + edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
> + if (!edid) {
> + DRM_ERROR("Failed to allocate edid\n");
> + return 0;
> + }
> +
> + ret = ptn3460_read_bytes(ptn_bridge, PTN3460_EDID_ADDR, edid,
> + EDID_LENGTH);
> + if (ret) {
> + kfree(edid);
> + num_modes = 0;
> + goto out;
> + }
> +
> + ptn_bridge->edid = (struct edid *)edid;
> + drm_mode_connector_update_edid_property(connector, ptn_bridge->edid);
> +
> + num_modes = drm_add_edid_modes(connector, ptn_bridge->edid);
> +
> +out:
> + if (power_off)
> + ptn3460_disable(ptn_bridge->bridge);
> +
> + return num_modes;
> +}
> +
> +static int ptn3460_mode_valid(struct drm_connector *connector,
> + struct drm_display_mode *mode)
> +{
> + return MODE_OK;
> +}
> +
> +struct drm_encoder *ptn3460_best_encoder(struct drm_connector *connector)
> +{
> + struct ptn3460_bridge *ptn_bridge;
> +
> + ptn_bridge = container_of(connector, struct ptn3460_bridge, connector);
> +
> + return ptn_bridge->encoder;
> +}
> +
> +struct drm_connector_helper_funcs ptn3460_connector_helper_funcs = {
> + .get_modes = ptn3460_get_modes,
> + .mode_valid = ptn3460_mode_valid,
> + .best_encoder = ptn3460_best_encoder,
> +};
> +
> +enum drm_connector_status ptn3460_detect(struct drm_connector *connector,
> + bool force)
> +{
> + return connector_status_connected;
> +}
> +
> +void ptn3460_connector_destroy(struct drm_connector *connector)
> +{
> + drm_connector_cleanup(connector);
> +}
> +
> +struct drm_connector_funcs ptn3460_connector_funcs = {
> + .dpms = drm_helper_connector_dpms,
> + .fill_modes = drm_helper_probe_single_connector_modes,
> + .detect = ptn3460_detect,
> + .destroy = ptn3460_connector_destroy,
> +};

Why do you try to add a new connector here? We already have the
connector for LCD, and also provides some callbacks for it. For this,
please see exynos_drm_display_ops of exynos_drm_fimd driver, and you
can add new callbacks to there such as init callback for bridge device
initialization if needed.

> +
> +int ptn3460_init(struct drm_device *dev, struct drm_encoder *encoder,
> + struct i2c_client *client, struct device_node *node)
> +{
> + int ret;
> + struct drm_bridge *bridge;
> + struct ptn3460_bridge *ptn_bridge;
> +
> + bridge = devm_kzalloc(dev->dev, sizeof(*bridge), GFP_KERNEL);
> + if (!bridge) {
> + DRM_ERROR("Failed to allocate drm bridge\n");
> + return -ENOMEM;
> + }
> +
> + ptn_bridge = devm_kzalloc(dev->dev, sizeof(*ptn_bridge), GFP_KERNEL);
> + if (!ptn_bridge) {
> + DRM_ERROR("Failed to allocate ptn bridge\n");
> + return -ENOMEM;
> + }
> +
> + ptn_bridge->client = client;
> + ptn_bridge->encoder = encoder;
> + ptn_bridge->bridge = bridge;
> + ptn_bridge->gpio_pd_n = of_get_named_gpio(node, "powerdown-gpio", 0);

Also, if a regulator is used instead?

> + if (gpio_is_valid(ptn_bridge->gpio_pd_n)) {
> + ret = gpio_request_one(ptn_bridge->gpio_pd_n,
> + GPIOF_OUT_INIT_HIGH, "PTN3460_PD_N");
> + if (ret) {
> + DRM_ERROR("Request powerdown-gpio failed (%d)\n", ret);
> + return ret;
> + }
> + }
> +
> + ptn_bridge->gpio_rst_n = of_get_named_gpio(node, "reset-gpio", 0);
> + if (gpio_is_valid(ptn_bridge->gpio_rst_n)) {
> + /*
> + * Request the reset pin low to avoid the bridge being
> + * initialized prematurely
> + */
> + ret = gpio_request_one(ptn_bridge->gpio_rst_n,
> + GPIOF_OUT_INIT_LOW, "PTN3460_RST_N");
> + if (ret) {
> + DRM_ERROR("Request reset-gpio failed (%d)\n", ret);
> + gpio_free(ptn_bridge->gpio_pd_n);
> + return ret;
> + }
> + }
> +
> + ret = of_property_read_u32(node, "edid-emulation",
> + &ptn_bridge->edid_emulation);
> + if (ret) {
> + DRM_ERROR("Can't read edid emulation value\n");
> + goto err;
> + }
> +
> + ret = drm_bridge_init(dev, bridge, &ptn3460_bridge_funcs);
> + if (ret) {
> + DRM_ERROR("Failed to initialize bridge with drm\n");
> + goto err;
> + }
> +
> + bridge->driver_private = ptn_bridge;
> + encoder->bridge = bridge;
> +
> + ret = drm_connector_init(dev, &ptn_bridge->connector,
> + &ptn3460_connector_funcs, DRM_MODE_CONNECTOR_LVDS);

So it seems that here's not right place to call drm_connector_init function.

Display pipeline path could be one of,
Display Controller Display bus
---------------------------------------------------------------------------
FIMD---------------------LVDS--------------------LCD,
or
FIMD----------------------eDP---------------------LCD,
or
FIMD------------------MIPI-DSI------------------LCD,
or
FIMD-------------------------------------------------LCD

And also in case using image enhancement chip,
mDNIe-------------FIMD-LITE between Display Controller and Display
bus.

So, wouldn't the right place below FIMD driver? :)


> + if (ret) {
> + DRM_ERROR("Failed to initialize connector with drm\n");
> + goto err;
> + }
> + drm_connector_helper_add(&ptn_bridge->connector,
> + &ptn3460_connector_helper_funcs);
> + drm_sysfs_connector_add(&ptn_bridge->connector);
> + drm_mode_connector_attach_encoder(&ptn_bridge->connector, encoder);
> +
> + return 0;
> +
> +err:
> + if (gpio_is_valid(ptn_bridge->gpio_pd_n))
> + gpio_free(ptn_bridge->gpio_pd_n);
> + if (gpio_is_valid(ptn_bridge->gpio_rst_n))
> + gpio_free(ptn_bridge->gpio_rst_n);
> + return ret;
> +}
> diff --git a/include/drm/bridge/ptn3460.h b/include/drm/bridge/ptn3460.h
> new file mode 100644
> index 0000000..157ffa1
> --- /dev/null
> +++ b/include/drm/bridge/ptn3460.h
> @@ -0,0 +1,36 @@
> +/*
> + * Copyright (C) 2013 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_PTN3460_H_
> +#define _DRM_BRIDGE_PTN3460_H_
> +
> +struct drm_device;
> +struct drm_encoder;
> +struct i2c_client;
> +struct device_node;
> +
> +#ifdef CONFIG_DRM_PTN3460
> +
> +int ptn3460_init(struct drm_device *dev, struct drm_encoder *encoder,
> + struct i2c_client *client, struct device_node *node);
> +#else
> +
> +int ptn3460_init(struct drm_device *dev, struct drm_encoder *encoder,
> + struct i2c_client *client, struct device_node *node)
> +{
> + return 0;
> +}
> +
> +#endif
> +
> +#endif
> --
> 1.8.4
>
>
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