Re: [RFC v2 2/2] drm/bridge: Add I2C based driver for ps8640 bridge

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Jitao,

a few comments below.

Am Montag, den 02.11.2015, 11:54 +0800 schrieb jitao shi:
[...]
> > +static int ps8640_check_valid_id(struct ps8640 *ps_bridge)

This could be bool and return true/false.

> > +{
> > +	struct i2c_client *client = ps_bridge->client;
> > +	u8 rev_id_low, rev_id_high, chip_id_low, chip_id_high;
> > +	int retry_cnt = 0;
> > +
> > +	do {
> > +		ps8640_regr(client, ps_bridge->base_reg + 4, PAGE4_CHIP_H,
> > +			    &chip_id_high);
> > +		if (chip_id_high != 0x30)
> > +			DRM_INFO("chip_id_high = 0x%x\n", chip_id_high);
> > +	} while ((retry_cnt++ < 2) && (chip_id_high != 0x30));
> > +
> > +	ps8640_regr(client, ps_bridge->base_reg + 4, PAGE4_REV_L, &rev_id_low);
> > +	ps8640_regr(client, ps_bridge->base_reg + 4, PAGE4_REV_H, &rev_id_high);
> > +	ps8640_regr(client, ps_bridge->base_reg + 4, PAGE4_CHIP_L,
> > +		    &chip_id_low);
> > +
> > +	if ((rev_id_low == 0x00) && (rev_id_high == 0x0a) &&
> > +	    (chip_id_low == 0x00) && (chip_id_high == 0x30))
> > +		return 1;
> > +
> > +	return 0;
> > +}
> > +
> > +static void ps8640_show_mcu_fw_version(struct ps8640 *ps_bridge)
> > +{
> > +	struct i2c_client *client = ps_bridge->client;
> > +	u8 major_ver, minor_ver;
> > +
> > +	ps8640_regr(client, ps_bridge->base_reg + 5, 0x4, &major_ver);
> > +	ps8640_regr(client, ps_bridge->base_reg + 5, 0x5, &minor_ver);
> > +
> > +	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->client;
> > +
> > +	if (ps8640_check_valid_id(ps_bridge)) {
> > +		ps8640_regw(client, ps_bridge->base_reg + 3, 0xfe, 0x13);
> > +		ps8640_regw(client, ps_bridge->base_reg + 3, 0xff, 0x18);
> > +		ps8640_regw(client, ps_bridge->base_reg + 3, 0xfe, 0x13);
> > +		ps8640_regw(client, ps_bridge->base_reg + 3, 0xff, 0x1c);

Can you introduce #defines with descriptive names for those magic
constants and register offsets, and maybe also i2c address offsets?

> > +
> > +		return 0;
> > +	}
> > +
> > +	return -1;

Never return -1 to signal a problem.
If there was an error, use a proper error code.

> > +}
> > +
> > +static void ps8640_prepare(struct ps8640 *ps_bridge)
> > +{
> > +	struct i2c_client *client = ps_bridge->client;
> > +	int err, retry_cnt = 0;
> > +	u8 set_vdo_done;
> > +
> > +	if (ps_bridge->enabled)
> > +		return;
> > +
> > +	if (drm_panel_prepare(ps_bridge->panel)) {
> > +		DRM_ERROR("failed to prepare panel\n");
> > +		return;
> > +	}
> > +
> > +	err = regulator_enable(ps_bridge->pwr_1v2_supply);
> > +	if (err < 0) {
> > +		DRM_ERROR("failed to enable pwr_1v2_supply: %d\n", err);

Missing panel unprepare.

> > +		return;
> > +	}
> > +
> > +	err = regulator_enable(ps_bridge->pwr_3v3_supply);
> > +	if (err < 0) {
> > +		DRM_ERROR("failed to enable pwr_3v3_supply: %d\n", err);

Missing panel unprepare and vdd12 regulator disable.

> > +		return;
> > +	}
> > +
> > +	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);
> > +		ps8640_regr(client, ps_bridge->base_reg + 2, 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;
> > +}
> > +
> > +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);
> > +
> > +	ps8640_bdg_enable(ps_bridge);
> > +
> > +	if (drm_panel_enable(ps_bridge->panel)) {
> > +		DRM_ERROR("failed to enable panel\n");
> > +		return;

The return is superfluous.

> > +	}
> > +}
> > +
> > +static void ps8640_disable(struct drm_bridge *bridge)
> > +{
> > +	struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
> > +
> > +	if (!ps_bridge->enabled)
> > +		return;
> > +
> > +	ps_bridge->enabled = false;
> > +
> > +	if (drm_panel_disable(ps_bridge->panel)) {
> > +		DRM_ERROR("failed to disable panel\n");
> > +		return;

Shouldn't we still disable the bridge, even if panel disable fails?

> > +	}
> > +
> > +	regulator_disable(ps_bridge->pwr_1v2_supply);
> > +	regulator_disable(ps_bridge->pwr_3v3_supply);
> > +	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);
> > +
> > +	if (drm_panel_unprepare(ps_bridge->panel)) {
> > +		DRM_ERROR("failed to unprepare panel\n");
> > +		return;

Drop the return.

> > +	}
> > +}
> > +
> > +static int ps8640_get_modes(struct drm_connector *connector)
> > +{
> > +	struct ps8640 *ps_bridge = connector_to_ps8640(connector);
> > +	struct i2c_client *client = ps_bridge->client;
> > +
> > +	ps8640_prepare(ps_bridge);
> > +	ps8640_regw(client, ps_bridge->base_reg + 2, 0xea, 0xd0);
> > +
> > +	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 = {
> > +	.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;
> > +}
> > +
> > +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\n");
> > +		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 *in_ep, *out_ep;
> > +	struct device_node *panel_node = NULL;
> > +	int ret;
> > +	u32 temp_reg;
> > +
> > +	ps_bridge = devm_kzalloc(dev, sizeof(*ps_bridge), GFP_KERNEL);
> > +	if (!ps_bridge)
> > +		return -ENOMEM;
> > +
> > +	in_ep = of_graph_get_next_endpoint(np, NULL);
> > +	if (in_ep) {
> > +		out_ep = of_graph_get_next_endpoint(np, in_ep);

Better use:
	port = of_graph_get_port_by_id(np, 1);
	out_ep = of_get_child_by_name(port, "endpoint");

> > +		of_node_put(in_ep);
> > +		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->client = client;
> > +
> > +	ps_bridge->pwr_3v3_supply = devm_regulator_get(dev, "vdd33-supply");
> > +	if (IS_ERR(ps_bridge->pwr_3v3_supply)) {
> > +		dev_err(dev, "cannot get ps_bridge->pwr_3v3_supply\n");

Instead of printing the variable name, just say "vdd3-supply". Also, it
is good practice to print the actual error value.

> > +		return PTR_ERR(ps_bridge->pwr_3v3_supply);
> > +	}
> > +
> > +	ps_bridge->pwr_1v2_supply = devm_regulator_get(dev, "vdd12-supply");
> > +	if (IS_ERR(ps_bridge->pwr_1v2_supply)) {
> > +		dev_err(dev, "cannot get ps_bridge->pwr_1v2_supply\n");

Same as above.

> > +		return PTR_ERR(ps_bridge->pwr_1v2_supply);
> > +	}
> > +
> > +	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);
> > +		DRM_ERROR("cannot get gpio_mode_sel_n %d\n", ret);

It would be better to use dev_err instead of DRM_ERROR. The same applies
to the DRM_ERRORs below.

> > +		return ret;
> > +	}
> > +
> > +	ret = gpiod_direction_output(ps_bridge->gpio_mode_sel_n, 1);
> > +	if (ret) {
> > +		DRM_ERROR("cannot configure gpio_mode_sel_n\n");
> > +		return ret;
> > +	}
> > +
> > +	ps_bridge->gpio_slp_n = devm_gpiod_get(&client->dev, "sleep-gpios",
> > +					       GPIOD_OUT_HIGH);
> > +	if (IS_ERR(ps_bridge->gpio_slp_n)) {
> > +		ret = PTR_ERR(ps_bridge->gpio_slp_n);
> > +		DRM_ERROR("cannot get gpio_slp_n %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = gpiod_direction_output(ps_bridge->gpio_slp_n, 1);
> > +	if (ret) {
> > +		DRM_ERROR("cannot configure gpio_slp_n\n");
> > +		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);
> > +		DRM_ERROR("cannot get gpio_rst_n %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = gpiod_direction_output(ps_bridge->gpio_rst_n, 1);
> > +	if (ret) {
> > +		DRM_ERROR("cannot configure gpio_rst_n\n");
> > +		return ret;
> > +	}
> > +
> > +	ret = of_property_read_u32(dev->of_node, "reg", &temp_reg);
> > +	if (ret) {
> > +		DRM_ERROR("Can't read base_reg value\n");
> > +		return ret;
> > +	}
> > +	ps_bridge->base_reg = temp_reg;

No need for this, the i2c address is already stored in client->addr.

> > +	ps_bridge->bridge.funcs = &ps8640_bridge_funcs;
> > +	ps_bridge->bridge.of_node = dev->of_node;
> > +	ret = drm_bridge_add(&ps_bridge->bridge);
> > +	if (ret) {
> > +		DRM_ERROR("Failed to add bridge\n");
> > +		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);
> > +
> > +	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",
> > +		.owner = THIS_MODULE,
> > +		.of_match_table = ps8640_match,
> > +	},
> > +};
> > +module_i2c_driver(ps8640_driver);
> > +
> > +MODULE_AUTHOR("Jitao Shi <jitao.shi@mediatek.com>");
> > +MODULE_AUTHOR("CK Hu <ck.hu@mediatek.com>");
> > +MODULE_DESCRIPTION("PARADE ps8640 DSI-eDP converter driver");
> > +MODULE_LICENSE("GPL v2");

best regards
Philipp