Re: [[RFC]DPU PATCH 1/4] drm/bridge: add support for sn65dsi86 bridge driver

[spanda-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org]

On 2018-04-19 20:44, Jordan Crouse wrote:
> On Wed, Apr 18, 2018 at 05:49:59PM +0530, Sandeep Panda wrote:
>> Add support for TI's sn65dsi86 dsi2edp bridge chip.
>> The chip converts DSI transmitted signal to eDP signal,
>> which is fed to the connected eDP panel.
>> 
>> This chip can be controlled via either i2c interface or
>> dsi interface. Currently in driver all the control registers
>> are being accessed through i2c interface only.
>> Also as of now HPD support has not been added to bridge
>> chip driver.
>> 
>> Signed-off-by: Sandeep Panda <spanda@codeaurora.org>
>> ---
>>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 742 
>> ++++++++++++++++++++++++++++++++++
>>  1 file changed, 742 insertions(+)
>>  create mode 100644 drivers/gpu/drm/bridge/ti-sn65dsi86.c
>> 
>> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c 
>> b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
>> new file mode 100644
>> index 0000000..c798f2f
>> --- /dev/null
>> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
>> @@ -0,0 +1,742 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
> 
> There should be a copyright here.
> 
>> +
>> +#include <linux/types.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/delay.h>
>> +#include <linux/i2c.h>
>> +#include <linux/gpio.h>
>> +#include <linux/of_gpio.h>
>> +#include <linux/of_graph.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <drm/drmP.h>
>> +#include <drm/drm_atomic.h>
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_crtc_helper.h>
>> +#include <drm/drm_mipi_dsi.h>
>> +#include <drm/drm_panel.h>
>> +
>> +#define SN_BRIDGE_REVISION_ID 0x2
>> +
>> +/* Link Training specific registers */
>> +#define SN_DEVICE_REV_REG			0x08
>> +#define SN_REFCLK_FREQ_REG			0x0A
>> +#define SN_DSI_LANES_REG			0x10
>> +#define SN_DSIA_CLK_FREQ_REG			0x12
>> +#define SN_ENH_FRAME_REG			0x5A
>> +#define SN_SSC_CONFIG_REG			0x93
>> +#define SN_DATARATE_CONFIG_REG			0x94
>> +#define SN_PLL_ENABLE_REG			0x0D
>> +#define SN_SCRAMBLE_CONFIG_REG			0x95
>> +#define SN_AUX_WDATA0_REG			0x64
>> +#define SN_AUX_ADDR_19_16_REG			0x74
>> +#define SN_AUX_ADDR_15_8_REG			0x75
>> +#define SN_AUX_ADDR_7_0_REG			0x76
>> +#define SN_AUX_LENGTH_REG			0x77
>> +#define SN_AUX_CMD_REG				0x78
>> +#define SN_ML_TX_MODE_REG			0x96
>> +#define SN_PAGE_SELECT_REG			0xFF
>> +#define SN_AUX_RDATA0_REG			0x79
>> +/* video config specific registers */
>> +#define SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG	0x20
>> +#define SN_CHA_ACTIVE_LINE_LENGTH_HIGH_REG	0x21
>> +#define SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG	0x24
>> +#define SN_CHA_VERTICAL_DISPLAY_SIZE_HIGH_REG	0x25
>> +#define SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG	0x2C
>> +#define SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG	0x2D
>> +#define SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG	0x30
>> +#define SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG	0x31
>> +#define SN_CHA_HORIZONTAL_BACK_PORCH_REG	0x34
>> +#define SN_CHA_VERTICAL_BACK_PORCH_REG		0x36
>> +#define SN_CHA_HORIZONTAL_FRONT_PORCH_REG	0x38
>> +#define SN_CHA_VERTICAL_FRONT_PORCH_REG		0x3A
>> +#define SN_DATA_FORMAT_REG			0x5B
>> +#define SN_COLOR_BAR_CONFIG_REG			0x3C
>> +
>> +#define DPPLL_CLK_SRC_REFCLK	0
>> +#define DPPLL_CLK_SRC_DSICLK	1
>> +#define MIN_DSI_CLK_FREQ_MHZ	40
>> +
>> +enum ti_sn_bridge_ref_clks {
>> +	SN_REF_CLK_12_MHZ = 0,
>> +	SN_REF_CLK_19_2_MHZ,
>> +	SN_REF_CLK_26_MHZ,
>> +	SN_REF_CLK_27_MHZ,
>> +	SN_REF_CLK_38_4_MHZ,
>> +	SN_REF_CLK_MAX,
>> +};
>> +
>> +struct ti_sn_bridge {
>> +	struct device *dev;
>> +	struct drm_bridge bridge;
>> +	struct drm_connector connector;
>> +	struct device_node *host_node;
>> +	struct mipi_dsi_device *dsi;
>> +	/* handle to the connected eDP panel */
>> +	struct drm_panel *panel;
>> +	int irq;
>> +	struct gpio_desc *irq_gpio;
>> +	/* list of gpios needed to enable the bridge functionality */
>> +	struct gpio_descs *enable_gpios;
>> +	unsigned int num_supplies;
>> +	struct regulator_bulk_data *supplies;
>> +	struct i2c_client *i2c_client;
>> +	struct i2c_adapter *ddc;
>> +	bool power_on;
>> +	u32 num_modes;
>> +	struct drm_display_mode curr_mode;
>> +};
>> +
>> +static int ti_sn_bridge_write(struct ti_sn_bridge *pdata, u8 reg, u8 
>> val)
>> +{
>> +	struct i2c_client *client = pdata->i2c_client;
>> +	u8 buf[2] = {reg, val};
>> +	struct i2c_msg msg = {
>> +		.addr = client->addr,
>> +		.flags = 0,
>> +		.len = 2,
>> +		.buf = buf,
>> +	};
>> +
>> +	if (i2c_transfer(client->adapter, &msg, 1) < 1) {
>> +		DRM_ERROR("i2c write failed\n");
>> +		return -EIO;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int ti_sn_bridge_read(struct ti_sn_bridge *pdata,
>> +					u8 reg, char *buf, u32 size)
>> +{
>> +	struct i2c_client *client = pdata->i2c_client;
>> +	struct i2c_msg msg[2] = {
>> +		{
>> +			.addr = client->addr,
>> +			.flags = 0,
>> +			.len = 1,
>> +			.buf = &reg,
>> +		},
>> +		{
>> +			.addr = client->addr,
>> +			.flags = I2C_M_RD,
>> +			.len = size,
>> +			.buf = buf,
>> +		}
>> +	};
>> +
>> +	if (i2c_transfer(client->adapter, msg, 2) != 2) {
>> +		DRM_ERROR("i2c read failed\n");
>> +		return -EIO;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void ti_sn_bridge_gpio_configure(struct ti_sn_bridge *pdata, 
>> bool on)
>> +{
>> +	int value, i = 0, num = 0;
>> +	int *value_array = NULL;
>> +
>> +	if (!pdata)
>> +		return;
> 
> pdata should always be valid here.
> 
>> +	value = on ? 1 : 0;
>> +	num = pdata->enable_gpios->ndescs;
>> +	value_array = kmalloc(num * sizeof(int), GFP_KERNEL);
>> +	if (value_array) {
>> +		for (i = 0; i < num; i++)
>> +			value_array[i] = value;
>> +		gpiod_set_array_value(num, pdata->enable_gpios->desc,
>> +				      value_array);
>> +		kfree(value_array);
>> +	}
>> +
>> +	if (pdata->irq_gpio)
>> +		gpiod_set_value(pdata->irq_gpio, value);
>> +
>> +	DRM_DEBUG("config to: %d\n", value);
>> +}
>> +
>> +static void ti_sn_bridge_power_ctrl(struct ti_sn_bridge *pdata, bool 
>> enable)
>> +{
>> +	static int ref_count;
>> +
>> +	if (!pdata)
>> +		return;
> 
> pdata should always be valid here.
> 
>> +	if (enable)
>> +		ref_count++;
>> +	else
>> +		ref_count--;
>> +
>> +	if (enable && (ref_count == 1)) {
>> +		ti_sn_bridge_gpio_configure(pdata, true);
>> +
>> +		if (regulator_bulk_enable(pdata->num_supplies,
>> +						pdata->supplies)) {
>> +			DRM_ERROR("bridge regulator enable failed\n");
>> +			return;
>> +		}
>> +		pdata->power_on = true;
>> +	} else if (!enable && !ref_count) {
>> +		regulator_bulk_disable(pdata->num_supplies, pdata->supplies);
>> +
>> +		ti_sn_bridge_gpio_configure(pdata, false);
>> +		pdata->power_on = false;
>> +	} else {
>> +		DRM_DEBUG("ti_sn_bridge power ctrl: %d refcount: %d\n",
>> +							enable, ref_count);
>> +	}
>> +}
>> +
>> +/* Connector funcs */
>> +static struct ti_sn_bridge *
>> +connector_to_ti_sn_bridge(struct drm_connector *connector)
>> +{
>> +	return container_of(connector, struct ti_sn_bridge, connector);
>> +}
>> +
>> +static int ti_sn_bridge_connector_get_modes(struct drm_connector 
>> *connector)
>> +{
>> +	struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);
>> +	struct drm_panel *panel = pdata->panel;
>> +	struct edid *edid;
>> +
>> +	if (panel) {
>> +		DRM_DEBUG("get mode from connected drm_panel\n");
>> +		pdata->num_modes = drm_panel_get_modes(panel);
>> +	} else {
>> +		/* get from EDID */
>> +		if (!pdata->ddc)
>> +			return 0;
>> +		ti_sn_bridge_power_ctrl(pdata, true);
>> +		edid = drm_get_edid(connector, pdata->ddc);
>> +		if (edid) {
>> +			drm_mode_connector_update_edid_property(connector,
>> +								edid);
>> +			pdata->num_modes = drm_add_edid_modes(connector, edid);
>> +			drm_edid_to_eld(connector, edid);
>> +			kfree(edid);
>> +		} else {
>> +			DRM_DEBUG("failed to get edid\n");
>> +		}
>> +		ti_sn_bridge_power_ctrl(pdata, false);
>> +	}
>> +
>> +	return pdata->num_modes;
>> +}
>> +
>> +static enum drm_mode_status
>> +ti_sn_bridge_connector_mode_valid(struct drm_connector *connector,
>> +			     struct drm_display_mode *mode)
>> +{
>> +	/* maximum supported resolution is 4K at 60 fps */
>> +	if (mode->clock > 594000)
>> +		return MODE_CLOCK_HIGH;
>> +
>> +	return MODE_OK;
>> +}
>> +
>> +static struct drm_connector_helper_funcs 
>> ti_sn_bridge_connector_helper_funcs = {
>> +	.get_modes = ti_sn_bridge_connector_get_modes,
>> +	.mode_valid = ti_sn_bridge_connector_mode_valid,
>> +};
>> +
>> +static enum drm_connector_status
>> +ti_sn_bridge_connector_detect(struct drm_connector *connector, bool 
>> force)
>> +{
>> +	struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);
>> +
>> +	/**
>> +	 * TODO: Currently if drm_panel is present, then always
>> +	 * return the status as connected. Need to add support to detect
>> +	 * device state for no panel(hot pluggable) scenarios.
>> +	 */
>> +	if (pdata->panel)
>> +		return connector_status_connected;
>> +	else
>> +		return connector_status_disconnected;
>> +}
>> +
>> +static const struct drm_connector_funcs ti_sn_bridge_connector_funcs 
>> = {
>> +	.fill_modes = drm_helper_probe_single_connector_modes,
>> +	.detect = ti_sn_bridge_connector_detect,
>> +	.destroy = drm_connector_cleanup,
>> +	.reset = drm_atomic_helper_connector_reset,
>> +	.atomic_duplicate_state = 
>> drm_atomic_helper_connector_duplicate_state,
>> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> +};
>> +
>> +static struct ti_sn_bridge *bridge_to_ti_sn_bridge(struct drm_bridge 
>> *bridge)
>> +{
>> +	return container_of(bridge, struct ti_sn_bridge, bridge);
>> +}
>> +
>> +static int ti_sn_bridge_read_device_rev(struct ti_sn_bridge *pdata)
>> +{
>> +	u8 rev = 0;
>> +	int ret = 0;
>> +
>> +	ret = ti_sn_bridge_read(pdata, SN_DEVICE_REV_REG, &rev, 1);
>> +	if (ret)
>> +		goto exit;
>> +
>> +	if (rev == SN_BRIDGE_REVISION_ID) {
>> +		DRM_DEBUG("ti_sn_bridge revision id: 0x%x\n", rev);
>> +	} else {
>> +		DRM_ERROR("ti_sn_bridge revision id mismatch\n");
> 
> I find it useful to print what the mismatch is so you can debug more
> effectively.
> 
>> +		ret = -EINVAL;
>> +	}
>> +
>> +exit:
>> +	return ret;
>> +}
>> +
>> +static const char * const ti_sn_bridge_supply_names[] = {
>> +	"vccio",
>> +	"vcca",
>> +};
>> +
>> +static int ti_sn_bridge_parse_regulators(struct ti_sn_bridge *pdata)
>> +{
>> +	unsigned int i;
>> +	int ret;
>> +
>> +	pdata->num_supplies = ARRAY_SIZE(ti_sn_bridge_supply_names);
>> +
>> +	pdata->supplies = devm_kcalloc(pdata->dev, pdata->num_supplies,
>> +				     sizeof(*pdata->supplies), GFP_KERNEL);
>> +	if (!pdata->supplies)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < pdata->num_supplies; i++)
>> +		pdata->supplies[i].supply = ti_sn_bridge_supply_names[i];
>> +
>> +	ret = devm_regulator_bulk_get(pdata->dev,
>> +			pdata->num_supplies, pdata->supplies);
>> +
>> +	return ret;
> 
> Nit: you can combine the above two lines and get rid of 'ret'.
> 
>> +}
>> +
>> +static void ti_sn_bridge_attach_panel(struct ti_sn_bridge *pdata)
>> +{
>> +	struct device_node *panel_node, *port, *endpoint;
>> +	struct drm_panel *panel = NULL;
>> +
>> +	port = of_graph_get_port_by_id(pdata->dev->of_node, 1);
>> +	if (port) {
>> +		endpoint = of_get_child_by_name(port, "endpoint");
>> +		of_node_put(port);
>> +		if (!endpoint) {
>> +			dev_err(pdata->dev, "no output endpoint found\n");
>> +			goto error;
>> +		}
>> +
>> +		panel_node = of_graph_get_remote_port_parent(endpoint);
>> +		of_node_put(endpoint);
>> +		if (!panel_node) {
>> +			dev_err(pdata->dev, "no output node found\n");
>> +			goto error;
>> +		}
>> +
>> +		panel = of_drm_find_panel(panel_node);
>> +		of_node_put(panel_node);
>> +		if (!panel) {
>> +			dev_err(pdata->dev, "no panel node found\n");
>> +			goto error;
>> +		}
>> +	}
>> +
>> +	pdata->panel = panel;
>> +	drm_panel_attach(panel, &pdata->connector);
>> +
>> +	return;
>> +
>> +error:
>> +	pdata->panel = NULL;
> 
> Is this needed?  isn't pdata->panel already null when we come in?  If 
> so
> you can just return the error cases and remove the label.

Just making sure it is NULL, not some uninitialized value, since this 
will be used through out the
driver to detect if a panel is connected or not and HDP needs to be 
supported or not.
> 
>> +}
>> +
>> +static int ti_sn_bridge_attach(struct drm_bridge *bridge)
>> +{
>> +	struct mipi_dsi_host *host;
>> +	struct mipi_dsi_device *dsi;
>> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
>> +	int ret;
>> +	const struct mipi_dsi_device_info info = { .type = "ti_sn_bridge",
>> +						   .channel = 0,
>> +						   .node = NULL,
>> +						 };
>> +
>> +	if (!bridge->encoder) {
>> +		DRM_ERROR("Parent encoder object not found");
> 
> Missing \n on the end of the string.
> 
>> +		return -ENODEV;
>> +	}
>> +
>> +	/* HPD not supported */
>> +	pdata->connector.polled = 0;
>> +
>> +	ret = drm_connector_init(bridge->dev, &pdata->connector,
>> +				 &ti_sn_bridge_connector_funcs,
>> +				 DRM_MODE_CONNECTOR_eDP);
> 
> The actual #define is CONNNECTOR_eDP?
yes.
> 
>> +	if (ret) {
>> +		DRM_ERROR("Failed to initialize connector with drm\n");
>> +		return ret;
>> +	}
>> +
>> +	drm_connector_helper_add(&pdata->connector,
>> +				 &ti_sn_bridge_connector_helper_funcs);
>> +	drm_mode_connector_attach_encoder(&pdata->connector, 
>> bridge->encoder);
>> +
>> +	host = of_find_mipi_dsi_host_by_node(pdata->host_node);
>> +	if (!host) {
>> +		DRM_ERROR("failed to find dsi host\n");
> 
> There isn't any tear down that needs to happen here?
> 
>> +		return -ENODEV;
>> +	}
>> +
>> +	dsi = mipi_dsi_device_register_full(host, &info);
>> +	if (IS_ERR(dsi)) {
>> +		DRM_ERROR("failed to create dsi device\n");
>> +		ret = PTR_ERR(dsi);
>> +		goto err_dsi_device;
> 
> Above you return directly but here you goto a return.  You should use 
> the same
> consistent approach in both cases.
> 
>> +	}
>> +
>> +	/* TODO: setting to 4 lanes always for now */
>> +	dsi->lanes = 4;
>> +	dsi->format = MIPI_DSI_FMT_RGB888;
>> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | 
>> MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
>> +			  MIPI_DSI_MODE_EOT_PACKET | MIPI_DSI_MODE_VIDEO_HSE;
>> +
>> +	ret = mipi_dsi_attach(dsi);
>> +	if (ret < 0) {
>> +		DRM_ERROR("failed to attach dsi to host\n");
>> +		goto err_dsi_attach;
>> +	}
>> +
>> +	pdata->dsi = dsi;
>> +
>> +	DRM_DEBUG("bridge attached\n");
>> +	/* attach panel to bridge */
>> +	ti_sn_bridge_attach_panel(pdata);
>> +
>> +	return 0;
>> +
>> +err_dsi_attach:
>> +	mipi_dsi_device_unregister(dsi);
>> +err_dsi_device:
>> +	return ret;
>> +}
>> +
>> +static void ti_sn_bridge_mode_set(struct drm_bridge *bridge,
>> +				    struct drm_display_mode *mode,
>> +				    struct drm_display_mode *adj_mode)
>> +{
>> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
>> +
>> +	DRM_DEBUG("mode_set: hdisplay=%d, vdisplay=%d, vrefresh=%d, 
>> clock=%d\n",
>> +		adj_mode->hdisplay, adj_mode->vdisplay,
>> +		adj_mode->vrefresh, adj_mode->clock);
>> +
>> +	drm_mode_copy(&pdata->curr_mode, adj_mode);
>> +}
>> +
>> +static void ti_sn_bridge_disable(struct drm_bridge *bridge)
>> +{
>> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
>> +	struct drm_panel *panel = pdata->panel;
>> +
>> +	if (panel) {
>> +		drm_panel_disable(panel);
>> +		drm_panel_unprepare(panel);
>> +	}
>> +
>> +	ti_sn_bridge_power_ctrl(pdata, false);
>> +}
>> +
>> +static void ti_sn_bridge_enable(struct drm_bridge *bridge)
>> +{
>> +	struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
>> +	struct drm_panel *panel = pdata->panel;
>> +	struct drm_display_mode *mode = &pdata->curr_mode;
>> +	u32 bit_rate_mhz, clk_freq_mhz;
>> +	u8 val = 0;
>> +
>> +	if (!pdata->num_modes)
>> +		return;
>> +
>> +	ti_sn_bridge_power_ctrl(pdata, true);
>> +
>> +	if (panel)
>> +		drm_panel_prepare(panel);
>> +
>> +	/* CLK_SRC config */
>> +	ti_sn_bridge_write(pdata, SN_REFCLK_FREQ_REG,
>> +			(DPPLL_CLK_SRC_REFCLK | (SN_REF_CLK_19_2_MHZ << 0x1)));
>> +
>> +	/* DSI_A lane config */
>> +	ti_sn_bridge_read(pdata, SN_DSI_LANES_REG, &val, 0x1);
>> +	val |= ((0x4 - pdata->dsi->lanes) & 0x03) << 0x3;
>> +	ti_sn_bridge_write(pdata, SN_DSI_LANES_REG, val);
>> +
>> +	/* DP lane config */
>> +	ti_sn_bridge_read(pdata, SN_SSC_CONFIG_REG, &val, 0x1);
>> +	val |= ((pdata->dsi->lanes - 0x1) & 0x03) << 0x4;
>> +	ti_sn_bridge_write(pdata, SN_SSC_CONFIG_REG, val);
>> +
>> +	/* set dsi clk frequency value */
>> +	bit_rate_mhz = (mode->clock / 1000) *
>> +			mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
>> +	clk_freq_mhz = bit_rate_mhz / (pdata->dsi->lanes * 2);
>> +	/* for each increment in val, frequency increases by 5MHz */
>> +	val = (MIN_DSI_CLK_FREQ_MHZ / 0x5) +
>> +		(((clk_freq_mhz - MIN_DSI_CLK_FREQ_MHZ) / 0x5) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_DSIA_CLK_FREQ_REG, val);
>> +
>> +	ti_sn_bridge_write(pdata, SN_DATARATE_CONFIG_REG, 0x80); /* set HBR 
>> */
>> +
>> +	ti_sn_bridge_write(pdata, SN_PLL_ENABLE_REG, 0x1); /* Enable PLL */
>> +	usleep_range(10000, 10001);
>> +
>> +	/* DPCD Register 0x0010A in Sink */
>> +	ti_sn_bridge_write(pdata, SN_AUX_WDATA0_REG, 0x01);
>> +	ti_sn_bridge_write(pdata, SN_AUX_ADDR_19_16_REG, 0x00);
>> +	ti_sn_bridge_write(pdata, SN_AUX_ADDR_15_8_REG, 0x01);
>> +	ti_sn_bridge_write(pdata, SN_AUX_ADDR_7_0_REG, 0x0A);
>> +	ti_sn_bridge_write(pdata, SN_AUX_LENGTH_REG, 0x01);
>> +	ti_sn_bridge_write(pdata, SN_AUX_CMD_REG, 0x81);
>> +	usleep_range(10000, 10001);
>> +
>> +	/* Semi auto link training mode */
>> +	ti_sn_bridge_write(pdata, SN_ML_TX_MODE_REG, 0x0A);
>> +	usleep_range(20000, 20001);
>> +
>> +	/* config video parameters */
>> +	ti_sn_bridge_write(pdata, SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG,
>> +			mode->hdisplay & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_ACTIVE_LINE_LENGTH_HIGH_REG,
>> +			(mode->hdisplay >> 0x8) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG,
>> +			mode->vdisplay & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VERTICAL_DISPLAY_SIZE_HIGH_REG,
>> +			(mode->hdisplay >> 0x8) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG,
>> +			(mode->htotal - mode->hsync_end) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG,
>> +			((mode->htotal - mode->hsync_end) >> 0x8) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG,
>> +			(mode->vtotal - mode->vsync_end) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG,
>> +			((mode->vtotal - mode->vsync_end) >> 0x8) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_HORIZONTAL_BACK_PORCH_REG,
>> +			(mode->hsync_start - mode->hdisplay) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VERTICAL_BACK_PORCH_REG,
>> +			(mode->vsync_start - mode->vdisplay) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_HORIZONTAL_FRONT_PORCH_REG,
>> +			(mode->hsync_end - mode->hsync_start) & 0xFF);
>> +	ti_sn_bridge_write(pdata, SN_CHA_VERTICAL_FRONT_PORCH_REG,
>> +			(mode->vsync_end - mode->vsync_start) & 0xFF);
>> +	if (pdata->dsi->format == MIPI_DSI_FMT_RGB888)
>> +		ti_sn_bridge_write(pdata, SN_DATA_FORMAT_REG, 0x00);
>> +	else
>> +		ti_sn_bridge_write(pdata, SN_DATA_FORMAT_REG, 0x01);
>> +	usleep_range(10000, 10001);
>> +
>> +	/* enable video stream */
>> +	ti_sn_bridge_read(pdata, SN_ENH_FRAME_REG, &val, 0x1);
>> +	val |= BIT(3);
>> +	ti_sn_bridge_write(pdata, SN_ENH_FRAME_REG, val);
>> +
>> +	if (panel)
>> +		drm_panel_enable(panel);
>> +}
>> +
>> +static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
>> +	.attach = ti_sn_bridge_attach,
>> +	.enable = ti_sn_bridge_enable,
>> +	.disable = ti_sn_bridge_disable,
>> +	.mode_set = ti_sn_bridge_mode_set,
>> +};
>> +
>> +static int ti_sn_bridge_parse_gpios(struct ti_sn_bridge *pdata)
>> +{
>> +	int ret = 0;
>> +
>> +	if (!pdata || !pdata->dev)
>> +		return -EINVAL;
> 
> Both of these are known to be valid at this point.
> 
>> +	pdata->enable_gpios = devm_gpiod_get_array(pdata->dev,
>> +						"enable", GPIOD_OUT_LOW);
>> +	if (IS_ERR(pdata->enable_gpios)) {
>> +		DRM_ERROR("failed to get enable gpio from DT\n");
>> +		ret = PTR_ERR(pdata->enable_gpios);
>> +		goto exit;
>> +	}
>> +
>> +	pdata->irq_gpio = devm_gpiod_get_optional(pdata->dev, "irq",
>> +						  GPIOD_OUT_LOW);
>> +	if (IS_ERR(pdata->irq_gpio))
>> +		DRM_ERROR("failed to get irq gpio from DT\n");
> 
> You need to set ret to PTR_ERR(pdata->irq_gpio) here.
> 
>> +
>> +exit:
>> +	return ret;
>> +}
>> +
>> +static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
>> +{
>> +	struct device_node *np = pdata->dev->of_node;
>> +	struct device_node *end_node;
>> +
>> +	end_node = of_graph_get_endpoint_by_regs(np, 0, 0);
>> +	if (!end_node) {
>> +		DRM_ERROR("remote endpoint not found\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	pdata->host_node = of_graph_get_remote_port_parent(end_node);
>> +	of_node_put(end_node);
>> +	if (!pdata->host_node) {
>> +		DRM_ERROR("remote node not found\n");
>> +		return -ENODEV;
>> +	}
>> +	of_node_put(pdata->host_node);
>> +
>> +	return 0;
>> +}
>> +
>> +static int ti_sn_bridge_probe(struct i2c_client *client,
>> +	 const struct i2c_device_id *id)
>> +{
>> +	struct ti_sn_bridge *pdata;
>> +	struct device_node *ddc_node;
>> +	int ret = 0;
>> +
>> +	if (!client || !client->dev.of_node) {
> 
> I doubt the i2c probe would send you a NULL value for client and you 
> are
> matching on a DT device, so there is a pretty solid argument that
> client->dev.of_node will be valid as well.
> 
>> +		DRM_ERROR("invalid input\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
>> +		DRM_ERROR("device doesn't support I2C\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	pdata = devm_kzalloc(&client->dev,
>> +		sizeof(struct ti_sn_bridge), GFP_KERNEL);
>> +	if (!pdata)
>> +		return -ENOMEM;
>> +
>> +	pdata->power_on = false;
>> +	pdata->dev = &client->dev;
>> +	pdata->i2c_client = client;
>> +	DRM_DEBUG("I2C address is %x\n", client->addr);
>> +
>> +	ret = ti_sn_bridge_parse_dsi_host(pdata);
>> +	if (ret) {
>> +		DRM_ERROR("failed to parse device tree\n");
> 
> ti_sn_bridge_parse_dsi_host prints a error message on every failure 
> point - you
> don't need another one here.
> 
>> +		goto err_dt_parse;
>> +	}
>> +
>> +	ret = ti_sn_bridge_parse_gpios(pdata);
>> +	if (ret) {
>> +		DRM_ERROR("failed to parse gpios from DT\n");
> 
> Same - all the paths are covered in the child function.
> 
>> +		goto err_dt_parse;
>> +	}
>> +
>> +	ret = ti_sn_bridge_parse_regulators(pdata);
>> +	if (ret) {
>> +		DRM_ERROR("failed to parse regulators\n");
>> +		goto err_dt_parse;
>> +	}
>> +
>> +	ddc_node = of_parse_phandle(pdata->dev->of_node, "ddc-i2c-bus", 0);
>> +	if (ddc_node) {
>> +		pdata->ddc = of_find_i2c_adapter_by_node(ddc_node);
>> +		of_node_put(ddc_node);
>> +		if (!pdata->ddc) {
>> +			dev_dbg(pdata->dev, "failed to read ddc node\n");
>> +			return -EPROBE_DEFER;
>> +		}
>> +	} else {
>> +		dev_dbg(pdata->dev, "no ddc property found\n");
>> +	}
>> +
>> +	ti_sn_bridge_power_ctrl(pdata, true);
>> +	ret = ti_sn_bridge_read_device_rev(pdata);
>> +	if (ret) {
>> +		DRM_ERROR("failed to read chip rev\n");
> 
> ti_sn_bridge_read_device_rev has you covered with the error messages.
> 
>> +		goto err_config;
>> +	} else {
>> +		DRM_DEBUG("bridge chip enabled successfully\n");
>> +	}
> 
> And also the debug messages for whatever its worth.
> 
>> +	ti_sn_bridge_power_ctrl(pdata, false);
>> +
>> +	i2c_set_clientdata(client, pdata);
>> +	dev_set_drvdata(&client->dev, pdata);
>> +
>> +	pdata->bridge.funcs = &ti_sn_bridge_funcs;
>> +	pdata->bridge.of_node = client->dev.of_node;
>> +
>> +	drm_bridge_add(&pdata->bridge);
>> +
>> +	return ret;
>> +
>> +err_config:
>> +	ti_sn_bridge_power_ctrl(pdata, false);
>> +err_dt_parse:
>> +	devm_kfree(&client->dev, pdata);
>> +	return ret;
>> +}
>> +
>> +static int ti_sn_bridge_remove(struct i2c_client *client)
>> +{
>> +	int ret = -EINVAL;
>> +	struct ti_sn_bridge *pdata = i2c_get_clientdata(client);
>> +
>> +	if (!pdata)
>> +		goto end;
> 
> pdata is very unlikely to be null here, but as long as this is a light 
> weight
> check, I don't think it hurts too much.
> 
>> +
>> +	mipi_dsi_detach(pdata->dsi);
>> +	mipi_dsi_device_unregister(pdata->dsi);
>> +
>> +	drm_bridge_remove(&pdata->bridge);
>> +
>> +	disable_irq(pdata->irq);
>> +	free_irq(pdata->irq, pdata);
>> +
>> +	ti_sn_bridge_gpio_configure(pdata, false);
>> +	i2c_put_adapter(pdata->ddc);
>> +
>> +	devm_kfree(&client->dev, pdata);
>> +
>> +end:
>> +	return ret;
>> +}
>> +
>> +static struct i2c_device_id ti_sn_bridge_id[] = {
>> +	{ "ti,sn65dsi86", 0},
>> +	{}
> 
> Missing a comma on the end of the empty entry.
> 
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ti_sn_bridge_id);
>> +
>> +static const struct of_device_id ti_sn_bridge_match_table[] = {
>> +	{.compatible = "ti,sn65dsi86"},
>> +	{}
> 
> Same.
> 
>> +};
>> +MODULE_DEVICE_TABLE(of, ti_sn_bridge_match_table);
>> +
>> +static struct i2c_driver ti_sn_bridge_driver = {
>> +	.driver = {
>> +		.name = "ti_sn65dsi86",
>> +		.owner = THIS_MODULE,
>> +		.of_match_table = ti_sn_bridge_match_table,
>> +	},
>> +	.probe = ti_sn_bridge_probe,
>> +	.remove = ti_sn_bridge_remove,
>> +	.id_table = ti_sn_bridge_id,
>> +};
>> +
>> +module_i2c_driver(ti_sn_bridge_driver);
>> +MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");
> 
> Looks like you are missing the module license here.
> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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