linux-kernel - Re: [PATCH v5 2/2] drm/panel: Add driver for Novatek NT36523

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Date:   Sat, 11 Mar 2023 13:38:52 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Jianhua Lu <lujianhua000@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Neil Armstrong <neil.armstrong@...aro.org>
Cc:     dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] drm/panel: Add driver for Novatek NT36523



On 11.03.2023 13:32, Jianhua Lu wrote:
> Add a driver for panels using the Novatek NT36523 display driver IC.
> 
> Signed-off-by: Jianhua Lu <lujianhua000@...il.com>
> ---
[...]

> +
> +static int nt36523_get_modes(struct drm_panel *panel,
> +			       struct drm_connector *connector)
> +{
> +	struct panel_info *pinfo = to_panel_info(panel);
> +	int i;
> +
> +	for (i = 0; i < pinfo->desc->num_modes; i++) {
> +		const struct drm_display_mode *m = &pinfo->desc->modes[i];
> +		struct drm_display_mode *mode;
> +
> +		mode = drm_mode_duplicate(connector->dev, m);
> +		if (!mode) {
> +			dev_err(panel->dev, "failed to add mode %ux%u@%u\n",
> +				m->hdisplay, m->vdisplay, drm_mode_vrefresh(m));
> +			return -ENOMEM;
> +		}
> +
> +		mode->type = DRM_MODE_TYPE_DRIVER;
> +		if (pinfo->desc->num_modes == 1)
> +			mode->type |= DRM_MODE_TYPE_PREFERRED;
That's not quite correct, as that means "if you have more than one
defined panel mode (say 60Hz and 120 Hz), there will be no preferred one".

Konrad
> +
> +		drm_mode_set_name(mode);
> +		drm_mode_probed_add(connector, mode);
> +	}
> +
> +	connector->display_info.width_mm = pinfo->desc->width_mm;
> +	connector->display_info.height_mm = pinfo->desc->height_mm;
> +	connector->display_info.bpc = pinfo->desc->bpc;
> +
> +	return pinfo->desc->num_modes;
> +}
> +
> +static const struct drm_panel_funcs nt36523_panel_funcs = {
> +	.disable = nt36523_disable,
> +	.prepare = nt36523_prepare,
> +	.unprepare = nt36523_unprepare,
> +	.get_modes = nt36523_get_modes,
> +};
> +
> +static int nt36523_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device *dev = &dsi->dev;
> +	struct device_node *dsi1;
> +	struct mipi_dsi_host *dsi1_host;
> +	struct panel_info *pinfo;
> +	const struct mipi_dsi_device_info *info;
> +	int i, ret;
> +
> +	pinfo = devm_kzalloc(dev, sizeof(*pinfo), GFP_KERNEL);
> +	if (!pinfo)
> +		return -ENOMEM;
> +
> +	pinfo->vddio = devm_regulator_get(dev, "vddio");
> +	if (IS_ERR(pinfo->vddio))
> +		return dev_err_probe(dev, PTR_ERR(pinfo->vddio), "failed to get vddio regulator\n");
> +
> +	pinfo->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(pinfo->reset_gpio))
> +		return dev_err_probe(dev, PTR_ERR(pinfo->reset_gpio), "failed to get reset gpio\n");
> +
> +	pinfo->desc = of_device_get_match_data(dev);
> +	if (!pinfo->desc)
> +		return -ENODEV;
> +
> +	/* If the panel is dual dsi, register DSI1 */
> +	if (pinfo->desc->is_dual_dsi) {
> +		info = &pinfo->desc->dsi_info;
> +
> +		dsi1 = of_graph_get_remote_node(dsi->dev.of_node, 1, -1);
> +		if (!dsi1) {
> +			dev_err(dev, "cannot get secondary DSI node.\n");
> +			return -ENODEV;
> +		}
> +
> +		dsi1_host = of_find_mipi_dsi_host_by_node(dsi1);
> +		of_node_put(dsi1);
> +		if (!dsi1_host)
> +			return dev_err_probe(dev, -EPROBE_DEFER, "cannot get secondary DSI host\n");
> +
> +		pinfo->dsi[1] = mipi_dsi_device_register_full(dsi1_host, info);
> +		if (!pinfo->dsi[1]) {
> +			dev_err(dev, "cannot get secondary DSI device\n");
> +			return -ENODEV;
> +		}
> +	}
> +
> +	pinfo->dsi[0] = dsi;
> +	mipi_dsi_set_drvdata(dsi, pinfo);
> +	drm_panel_init(&pinfo->panel, dev, &nt36523_panel_funcs, DRM_MODE_CONNECTOR_DSI);
> +
> +	ret = drm_panel_of_backlight(&pinfo->panel);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to get backlight\n");
> +
> +	drm_panel_add(&pinfo->panel);
> +
> +	for (i = 0; i < DSI_NUM_MIN + pinfo->desc->is_dual_dsi; i++) {
> +		pinfo->dsi[i]->lanes = pinfo->desc->lanes;
> +		pinfo->dsi[i]->format = pinfo->desc->format;
> +		pinfo->dsi[i]->mode_flags = pinfo->desc->mode_flags;
> +
> +		ret = mipi_dsi_attach(pinfo->dsi[i]);
> +		if (ret < 0)
> +			return dev_err_probe(dev, ret, "cannot attach to DSI%d host.\n", i);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id nt36523_of_match[] = {
> +	{
> +		.compatible = "xiaomi,elish-boe-nt36523",
> +		.data = &elish_boe_desc,
> +	},
> +	{
> +		.compatible = "xiaomi,elish-csot-nt36523",
> +		.data = &elish_csot_desc,
> +	},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, nt36523_of_match);
> +
> +static struct mipi_dsi_driver nt36523_driver = {
> +	.probe = nt36523_probe,
> +	.remove = nt36523_remove,
> +	.driver = {
> +		.name = "panel-novatek-nt36523",
> +		.of_match_table = nt36523_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(nt36523_driver);
> +
> +MODULE_AUTHOR("Jianhua Lu <lujianhua000@...il.com>");
> +MODULE_DESCRIPTION("DRM driver for Novatek NT36523 based MIPI DSI panels");
> +MODULE_LICENSE("GPL");