Re: [PATCH v6 2/2] drm/bridge: Add I2C based driver for ps8640 bridge

From: Daniel Kurtz
Date: Tue Dec 15 2015 - 01:59:24 EST

On Tue, Dec 15, 2015 at 11:30 AM, Jitao Shi <jitao.shi@xxxxxxxxxxxx> wrote:
> This patch adds drm_bridge driver for parade DSI to eDP bridge chip.
>
> Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
> ---
> Changes since v5
> -fix compile errors when CONFIG_GPIOLIB=n
> ---
> drivers/gpu/drm/bridge/Kconfig | 10 +
> drivers/gpu/drm/bridge/Makefile | 1 +
> drivers/gpu/drm/bridge/parade-ps8640.c | 472 ++++++++++++++++++++++++++++++++
> 3 files changed, 483 insertions(+)
> create mode 100644 drivers/gpu/drm/bridge/parade-ps8640.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 6dddd39..dcfdbc9 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -41,4 +41,14 @@ config DRM_PARADE_PS8622
> ---help---
> Parade eDP-LVDS bridge chip driver.
>
> +config DRM_PARADE_PS8640
> + tristate "Parade PS8640 MIPI DSI to eDP Converter"
> + depends on OF
> + select DRM_KMS_HELPER
> + select DRM_PANEL
> + ---help---
> + Choose this option if you have PS8640 for display
> + The PS8640 is a high-performance and low-power
> + MIPI DSI to eDP converter
> +
> endmenu
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index d4e28be..272e3c01 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -4,3 +4,4 @@ obj-$(CONFIG_DRM_DW_HDMI) += dw_hdmi.o
> obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw_hdmi-ahb-audio.o
> obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
> +obj-$(CONFIG_DRM_PARADE_PS8640) += parade-ps8640.o
> diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
> new file mode 100644
> index 0000000..bf0c3c37
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
> @@ -0,0 +1,472 @@
> +/*
> + * Copyright (c) 2014 MediaTek Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_graph.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drm_panel.h>
> +
> +#include <drmP.h>
> +#include <drm_crtc_helper.h>
> +#include <drm_crtc.h>
> +#include <drm_mipi_dsi.h>
> +#include <drm_atomic_helper.h>
> +
> +#define PAGE2_GPIO_L 0xa6
> +#define PAGE2_GPIO_H 0xa7
> +#define PS_GPIO9 BIT(1)
> +#define PAGE2_I2C_BYPASS 0xea
> +#define I2C_BYPASS_EN 0xd0
> +
> +#define PAGE3_SET_ADD 0xfe
> +#define PAGE3_SET_VAL 0xff
> +#define VDO_CTL_ADD 0x13
> +#define VDO_DIS 0x18
> +#define VDO_EN 0x1c
> +
> +#define PAGE4_REV_L 0xf0
> +#define PAGE4_REV_H 0xf1
> +#define PAGE4_CHIP_L 0xf2
> +#define PAGE4_CHIP_H 0xf3
> +
> +#define bridge_to_ps8640(e) container_of(e, struct ps8640, bridge)
> +#define connector_to_ps8640(e) container_of(e, struct ps8640, connector)
> +
> +struct ps8640 {
> + struct drm_connector connector;
> + struct drm_bridge bridge;
> + struct i2c_client *page[6];
> + struct ps8640_driver_data *driver_data;
> + struct regulator *pwr_1v2_supply;
> + struct regulator *pwr_3v3_supply;
> + struct drm_panel *panel;
> + struct gpio_desc *gpio_rst_n;
> + struct gpio_desc *gpio_slp_n;
> + struct gpio_desc *gpio_mode_sel_n;
> + bool enabled;
> +};
> +
> +static int ps8640_regr(struct i2c_client *client, u8 reg, u8 *value)
> +{
> + int ret;
> +
> + ret = i2c_master_send(client, &reg, 1);
> + if (ret <= 0) {
> + dev_err(&client->dev, "Failed to send i2c command, ret=%d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = i2c_master_recv(client, value, 1);
> + if (ret <= 0) {
> + dev_err(&client->dev, "Failed to recv i2c data, ret=%d\n", ret);
> + return ret;
> + }

i2c_transfer should be a bit more efficient for reading one byte.

> +
> + return 0;
> +}
> +
> +static int ps8640_regw(struct i2c_client *client, u8 reg, u8 value)
> +{
> + int ret;
> + char buf[2];
> +
> + buf[0] = reg;
> + buf[1] = value;
> + ret = i2c_master_send(client, buf, ARRAY_SIZE(buf));
> + if (ret <= 0) {
> + dev_err(&client->dev, "Failed to send i2c command, ret=%d\n",
> + ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static bool ps8640_check_valid_id(struct ps8640 *ps_bridge)
> +{
> + struct i2c_client *client = ps_bridge->page[4];
> + u8 rev_id_low, rev_id_high, chip_id_low, chip_id_high;
> + int retry_cnt = 0;
> +
> + do {
> + ps8640_regr(client, PAGE4_CHIP_H, &chip_id_high);

Check return value and propagate if non-zero.

> + if (chip_id_high != 0x30)
> + dev_info(&client->dev, "chip_id_high = 0x%x\n",
> + chip_id_high);
> + } while ((retry_cnt++ < 2) && (chip_id_high != 0x30));

Why is this loop retrying?
What could be happening here?
Please add a comment.

> +
> + ps8640_regr(client, PAGE4_REV_L, &rev_id_low);
> + ps8640_regr(client, PAGE4_REV_H, &rev_id_high);
> + ps8640_regr(client, PAGE4_CHIP_L, &chip_id_low);

Can you just read all 4 bytes in a single i2c transaction?

> +
> + if ((rev_id_low == 0x00) && (rev_id_high == 0x0a) &&
> + (chip_id_low == 0x00) && (chip_id_high == 0x30))
> + return true;
> +
> + return false;

return -ENODEV if no device is found?

> +}
> +
> +static void ps8640_show_mcu_fw_version(struct ps8640 *ps_bridge)
> +{
> + struct i2c_client *client = ps_bridge->page[5];
> + u8 major_ver, minor_ver;
> +
> + ps8640_regr(client, 0x4, &major_ver);
> + ps8640_regr(client, 0x5, &minor_ver);

Please #define these FW version registers.
Also, can you read them in a single i2c transaction?

> +
> + DRM_INFO_ONCE("ps8640 rom fw version %d.%d\n", major_ver, minor_ver);
> +}
> +
> +static int ps8640_bdg_enable(struct ps8640 *ps_bridge)
> +{
> + struct i2c_client *client = ps_bridge->page[3];
> +
> + if (ps8640_check_valid_id(ps_bridge)) {

Usually it is prefered to fail fast, so:

ret = ps8640_check_valid_id(ps_bridge);
if (ret)
return ret;
...
return 0;


> + ps8640_regw(client, PAGE3_SET_ADD, VDO_CTL_ADD);
> + ps8640_regw(client, PAGE3_SET_VAL, VDO_DIS);

Combine into 1 i2c transaction.

> + ps8640_regw(client, PAGE3_SET_ADD, VDO_CTL_ADD);
> + ps8640_regw(client, PAGE3_SET_VAL, VDO_DIS);

Why are you doing this twice?
Add a comment.

> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static void ps8640_prepare(struct ps8640 *ps_bridge)
> +{
> + struct i2c_client *client = ps_bridge->page[2];
> + int err, retry_cnt = 0;
> + u8 set_vdo_done;
> +
> + if (ps_bridge->enabled)
> + return;
> +
> + err = drm_panel_prepare(ps_bridge->panel);
> + if (err < 0) {
> + DRM_ERROR("failed to prepare panel: %d\n", err);
> + return;
> + }
> +
> + /* delay for power stable */
> + usleep_range(500, 700);
> +
> + err = regulator_enable(ps_bridge->pwr_1v2_supply);
> + if (err < 0) {
> + DRM_ERROR("failed to enable vdd12-supply: %d\n", err);
> + goto err_panel_unprepare;
> + }
> +
> + err = regulator_enable(ps_bridge->pwr_3v3_supply);
> + if (err < 0) {
> + DRM_ERROR("failed to enable vdd33-supply: %d\n", err);
> + goto err_regulator_disable;

Slightly less confusing:

goto err_regulator_1v2_disable;

> + }
> +
> + gpiod_set_value(ps_bridge->gpio_slp_n, 1);
> + gpiod_set_value(ps_bridge->gpio_rst_n, 0);
> + usleep_range(500, 700);
> + gpiod_set_value(ps_bridge->gpio_rst_n, 1);
> +
> + do {
> + msleep(50);

50 ms seems pretty slow polling interval.
How long is this expected to take?

> + ps8640_regr(client, PAGE2_GPIO_H, &set_vdo_done);
> + } while ((retry_cnt++ < 70) && ((set_vdo_done & PS_GPIO9) != PS_GPIO9));
> +
> + ps8640_show_mcu_fw_version(ps_bridge);
> + ps_bridge->enabled = true;
> +
> + return;
> +
> +err_regulator_disable:
> + regulator_disable(ps_bridge->pwr_1v2_supply);
> +err_panel_unprepare:
> + drm_panel_unprepare(ps_bridge->panel);
> +}
> +
> +static void ps8640_pre_enable(struct drm_bridge *bridge)
> +{
> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> +
> + ps8640_prepare(ps_bridge);
> +}
> +
> +static void ps8640_enable(struct drm_bridge *bridge)
> +{
> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> + int err;
> +
> + ps8640_bdg_enable(ps_bridge);
> +
> + err = drm_panel_enable(ps_bridge->panel);
> + if (err < 0)
> + DRM_ERROR("failed to enable panel: %d\n", err);
> +}
> +
> +static void ps8640_disable(struct drm_bridge *bridge)
> +{
> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> + int err;
> +
> + if (!ps_bridge->enabled)
> + return;
> +
> + ps_bridge->enabled = false;
> +
> + err = drm_panel_disable(ps_bridge->panel);
> + if (err < 0)
> + DRM_ERROR("failed to disable panel: %d\n", err);
> +
> + regulator_disable(ps_bridge->pwr_1v2_supply);
> + regulator_disable(ps_bridge->pwr_3v3_supply);

Not sure if it matters, but...
since you enabled them 1v2 then 3v3, its usually better to turn them
off in opposite order, so: 3v3 then 1v2.

> + gpiod_set_value(ps_bridge->gpio_rst_n, 0);
> + gpiod_set_value(ps_bridge->gpio_slp_n, 0);
> +}
> +
> +static void ps8640_post_disable(struct drm_bridge *bridge)
> +{
> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> + int err;
> +
> + err = drm_panel_unprepare(ps_bridge->panel);
> + if (err)
> + DRM_ERROR("failed to unprepare panel: %d\n", err);
> +}
> +
> +static int ps8640_get_modes(struct drm_connector *connector)
> +{
> + struct ps8640 *ps_bridge = connector_to_ps8640(connector);
> + struct i2c_client *client = ps_bridge->page[2];
> +
> + ps8640_prepare(ps_bridge);
> + ps8640_regw(client, PAGE2_I2C_BYPASS, I2C_BYPASS_EN);

Do you need to unset bypass mode after getting modes?
If not, perhaps you can just set this once during prepare?

> +
> + return drm_panel_get_modes(ps_bridge->panel);
> +}
> +
> +static struct drm_encoder *ps8640_best_encoder(struct drm_connector *connector)
> +{
> + struct ps8640 *ps_bridge;
> +
> + ps_bridge = connector_to_ps8640(connector);
> + return ps_bridge->bridge.encoder;
> +}
> +
> +static const struct drm_connector_helper_funcs
> + ps8640_connector_helper_funcs = {

Indentation looks a bit funny. I think you want another tab here.

> + .get_modes = ps8640_get_modes,
> + .best_encoder = ps8640_best_encoder,
> +};
> +
> +static enum drm_connector_status ps8640_detect(struct drm_connector *connector,
> + bool force)
> +{
> + return connector_status_connected;

Always?

> +}
> +
> +static void ps8640_connector_destroy(struct drm_connector *connector)
> +{
> + drm_connector_unregister(connector);
> + drm_connector_cleanup(connector);
> +}
> +
> +static const struct drm_connector_funcs ps8640_connector_funcs = {
> + .dpms = drm_atomic_helper_connector_dpms,
> + .fill_modes = drm_helper_probe_single_connector_modes,
> + .detect = ps8640_detect,
> + .destroy = ps8640_connector_destroy,
> + .reset = drm_atomic_helper_connector_reset,
> + .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> + .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +int ps8640_bridge_attach(struct drm_bridge *bridge)
> +{
> + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> + int ret;
> +
> + if (!bridge->encoder) {
> + DRM_ERROR("Parent encoder object not found");
> + return -ENODEV;
> + }
> +
> + ret = drm_connector_init(bridge->dev, &ps_bridge->connector,
> + &ps8640_connector_funcs,
> + DRM_MODE_CONNECTOR_eDP);
> +
> + if (ret) {
> + DRM_ERROR("Failed to initialize connector with drm: %d\n", ret);
> + return ret;
> + }
> +
> + drm_connector_helper_add(&ps_bridge->connector,
> + &ps8640_connector_helper_funcs);
> + drm_connector_register(&ps_bridge->connector);
> +
> + ps_bridge->connector.dpms = DRM_MODE_DPMS_ON;
> + drm_mode_connector_attach_encoder(&ps_bridge->connector,
> + bridge->encoder);
> +
> + if (ps_bridge->panel)
> + drm_panel_attach(ps_bridge->panel, &ps_bridge->connector);
> +
> + return ret;
> +}
> +
> +static bool ps8640_bridge_mode_fixup(struct drm_bridge *bridge,
> + const struct drm_display_mode *mode,
> + struct drm_display_mode *adjusted_mode)
> +{
> + return true;
> +}
> +
> +static const struct drm_bridge_funcs ps8640_bridge_funcs = {
> + .attach = ps8640_bridge_attach,
> + .mode_fixup = ps8640_bridge_mode_fixup,
> + .disable = ps8640_disable,
> + .post_disable = ps8640_post_disable,
> + .pre_enable = ps8640_pre_enable,
> + .enable = ps8640_enable,
> +};
> +
> +static int ps8640_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + struct ps8640 *ps_bridge;
> + struct device_node *np = dev->of_node;
> + struct device_node *port, *out_ep;
> + struct device_node *panel_node = NULL;
> + int i, ret;
> +
> + ps_bridge = devm_kzalloc(dev, sizeof(*ps_bridge), GFP_KERNEL);
> + if (!ps_bridge)
> + return -ENOMEM;
> +
> + /* port@1 is ps8640 output port */
> + port = of_graph_get_port_by_id(np, 1);
> + if (port) {
> + out_ep = of_get_child_by_name(port, "endpoint");
> + of_node_put(port);
> + if (out_ep) {
> + panel_node = of_graph_get_remote_port_parent(out_ep);
> + of_node_put(out_ep);
> + }
> + }
> + if (panel_node) {
> + ps_bridge->panel = of_drm_find_panel(panel_node);
> + of_node_put(panel_node);
> + if (!ps_bridge->panel)
> + return -EPROBE_DEFER;
> + }
> +
> + ps_bridge->page[0] = client;
> + for (i = 1; i < 6; i++)
> + ps_bridge->page[i] = i2c_new_dummy(client->adapter,
> + client->addr + i);

Can you add a comment somewhere explaining what these extra i2c clients are for?

Also, if after this in probe() fails, unregister our these i2c_clients.
Or, move this after the devm_*() calls.

> +
> + ps_bridge->pwr_3v3_supply = devm_regulator_get(dev, "vdd33");
> + if (IS_ERR(ps_bridge->pwr_3v3_supply)) {
> + ret = PTR_ERR(ps_bridge->pwr_3v3_supply);
> + dev_err(dev, "cannot get vdd33 supply: %d\n", ret);
> + return ret;
> + }
> +
> + ps_bridge->pwr_1v2_supply = devm_regulator_get(dev, "vdd12");
> + if (IS_ERR(ps_bridge->pwr_1v2_supply)) {
> + ret = PTR_ERR(ps_bridge->pwr_1v2_supply);
> + dev_err(dev, "cannot get vdd12 supply: %d\n", ret);
> + return ret;
> + }
> +
> + ps_bridge->gpio_mode_sel_n = devm_gpiod_get(&client->dev, "mode-sel",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(ps_bridge->gpio_mode_sel_n)) {
> + ret = PTR_ERR(ps_bridge->gpio_mode_sel_n);
> + dev_err(dev, "cannot get gpio_mode_sel_n %d\n", ret);
> + return ret;
> + }
> +
> + ps_bridge->gpio_slp_n = devm_gpiod_get(&client->dev, "sleep",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(ps_bridge->gpio_slp_n)) {
> + ret = PTR_ERR(ps_bridge->gpio_slp_n);
> + dev_err(dev, "cannot get gpio_slp_n: %d\n", ret);
> + return ret;
> + }
> +
> + ps_bridge->gpio_rst_n = devm_gpiod_get(&client->dev, "reset",
> + GPIOD_OUT_HIGH);
> + if (IS_ERR(ps_bridge->gpio_rst_n)) {
> + ret = PTR_ERR(ps_bridge->gpio_rst_n);
> + dev_err(dev, "cannot get gpio_rst_n: %d\n", ret);
> + return ret;
> + }
> +
> + ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
> + ps_bridge->bridge.of_node = dev->of_node;
> + ret = drm_bridge_add(&ps_bridge->bridge);
> + if (ret) {
> + dev_err(dev, "Failed to add bridge: %d\n", ret);
> + return ret;
> + }
> +
> + i2c_set_clientdata(client, ps_bridge);
> +
> + return 0;
> +}
> +
> +static int ps8640_remove(struct i2c_client *client)
> +{
> + struct ps8640 *ps_bridge = i2c_get_clientdata(client);
> +

i2c_unregister_device() the pages.

> + drm_bridge_remove(&ps_bridge->bridge);
> +
> + return 0;
> +}
> +
> +static const struct i2c_device_id ps8640_i2c_table[] = {
> + {"parade,ps8640", 0},
> + {},
> +};
> +MODULE_DEVICE_TABLE(i2c, ps8640_i2c_table);
> +
> +static const struct of_device_id ps8640_match[] = {
> + { .compatible = "parade,ps8640" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, ps8640_match);
> +
> +static struct i2c_driver ps8640_driver = {
> + .id_table = ps8640_i2c_table,
> + .probe = ps8640_probe,
> + .remove = ps8640_remove,
> + .driver = {
> + .name = "parade,ps8640",
> + .of_match_table = ps8640_match,
> + },
> +};
> +module_i2c_driver(ps8640_driver);
> +
> +MODULE_AUTHOR("Jitao Shi <jitao.shi@xxxxxxxxxxxx>");
> +MODULE_AUTHOR("CK Hu <ck.hu@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("PARADE ps8640 DSI-eDP converter driver");
> +MODULE_LICENSE("GPL v2");
> --
> 1.7.9.5
>
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