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Date:   Sat, 9 May 2020 16:48:50 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     srk@48.io
Cc:     Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Lubomir Rintel <lkundrak@v3.sk>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Marek Vasut <marex@denx.de>,
        Sean Cross <xobs@kosagi.com>
Subject: Re: [PATCH 2/2] drm/bridge: Add ITE IT6251 bridge driver
Message-ID: <20200509134850.GB5946@pendragon.ideasonboard.com>
References: <20200509111732.26102-1-srk@48.io>
 <20200509111732.26102-3-srk@48.io>
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In-Reply-To: <20200509111732.26102-3-srk@48.io>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Richard,

Thank you for the patch.

On Sat, May 09, 2020 at 01:17:32PM +0200, srk@48.io wrote:
> From: Marek Vasut <marex@denx.de>
> 
> Add driver for the ITE IT6251 LVDS-to-eDP bridge.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Signed-off-by: Richard Marko <srk@48.io>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Sean Cross <xobs@kosagi.com>
> To: dri-devel@lists.freedesktop.org
> ---
>  drivers/gpu/drm/bridge/Kconfig      |  12 +
>  drivers/gpu/drm/bridge/Makefile     |   1 +
>  drivers/gpu/drm/bridge/ite-it6251.c | 582 ++++++++++++++++++++++++++++
>  3 files changed, 595 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/ite-it6251.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index aaed2347ace9..934896a4ab2d 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -38,6 +38,18 @@ config DRM_DISPLAY_CONNECTOR
>  	  on ARM-based platforms. Saying Y here when this driver is not needed
>  	  will not cause any issue.
>  
> +config DRM_ITE_IT6251
> +	tristate "ITE IT6251 LVDS/eDP bridge"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select DRM_PANEL
> +	select REGMAP_I2C
> +	help
> +	  Driver for ITE IT6251 LVDS-eDP bridge chip driver. This is used
> +	  in Novena open-hardware laptop with eDP based panel.
> +	  IT6251 supports LVDS input and DisplayPort 1.1a output,
> +	  resolution up to 1080P and 10-bit color depth.
> +
>  config DRM_LVDS_CODEC
>  	tristate "Transparent LVDS encoders and decoders support"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 6fb062b5b0f0..4c195dc42fce 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-$(CONFIG_DRM_CDNS_DSI) += cdns-dsi.o
>  obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
> +obj-$(CONFIG_DRM_ITE_IT6251) += ite-it6251.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
> diff --git a/drivers/gpu/drm/bridge/ite-it6251.c b/drivers/gpu/drm/bridge/ite-it6251.c
> new file mode 100644
> index 000000000000..b8534fb62c9d
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ite-it6251.c
> @@ -0,0 +1,582 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2014 Sean Cross <xobs@kosagi.com>
> + *
> + * Rework for mainline: Marek Vasut <marex@denx.de>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_graph.h>
> +#include <linux/of_platform.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <drm/drm_panel.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +struct it6251_bridge {
> +	struct i2c_client	*client;
> +	struct i2c_client	*lvds_client;
> +	struct regmap		*regmap;
> +	struct regmap		*lvds_regmap;
> +	struct regulator	*regulator;
> +
> +	struct drm_connector	connector;
> +	struct drm_bridge	bridge;
> +	struct drm_panel	*panel;
> +};
> +
> +/* Register definitions */
> +#define IT6251_VENDOR_ID_LOW			0x00
> +#define IT6251_VENDOR_ID_HIGH			0x01
> +#define IT6251_DEVICE_ID_LOW			0x02
> +#define IT6251_DEVICE_ID_HIGH			0x03
> +#define IT6251_SYSTEM_STATUS			0x0d
> +#define IT6251_SYSTEM_STATUS_RINTSTATUS		BIT(0)
> +#define IT6251_SYSTEM_STATUS_RHPDSTATUS		BIT(1)
> +#define IT6251_SYSTEM_STATUS_RVIDEOSTABLE	BIT(2)
> +#define IT6251_SYSTEM_STATUS_RPLL_IOLOCK	BIT(3)
> +#define IT6251_SYSTEM_STATUS_RPLL_XPLOCK	BIT(4)
> +#define IT6251_SYSTEM_STATUS_RPLL_SPLOCK	BIT(5)
> +#define IT6251_SYSTEM_STATUS_RAUXFREQ_LOCK	BIT(6)
> +#define IT6251_REF_STATE			0x0e
> +#define IT6251_REF_STATE_MAIN_LINK_DISABLED	BIT(0)
> +#define IT6251_REF_STATE_AUX_CHANNEL_READ	BIT(1)
> +#define IT6251_REF_STATE_CR_PATTERN		BIT(2)
> +#define IT6251_REF_STATE_EQ_PATTERN		BIT(3)
> +#define IT6251_REF_STATE_NORMAL_OPERATION	BIT(4)
> +#define IT6251_REF_STATE_MUTED			BIT(5)
> +#define IT6251_RPCLK_CNT_LOW			0x13
> +#define IT6251_RPCLK_CNT_HIGH			0x14
> +#define IT6251_RPC_REQ				0x2b
> +#define IT6251_RPC_REQ_RPC_FIFOFULL		BIT(6)
> +#define IT6251_RPC_REQ_RPC_FIFOEMPTY		BIT(7)
> +#define IT6251_PCLK_CNT_LOW			0x57
> +#define IT6251_PCLK_CNT_HIGH			0x58
> +#define IT6251_DPHDEW_LOW			0xa5
> +#define IT6251_DPHDEW_HIGH			0xa6
> +#define IT6251_DPVDEW_LOW			0xaf
> +#define IT6251_DPVDEW_HIGH			0xb0
> +#define IT6251_LVDS_PORT_ADDR			0xfd
> +#define IT6251_LVDS_PORT_CTRL			0xfe
> +#define IT6251_LVDS_PORT_CTRL_EN		BIT(0)
> +
> +/*
> + * Register programming sequences.
> + * NOTE: There is a lot of registers here which are completely undocumented
> + *       and/or their meaning is not clear from the little documentation
> + *       that is available for this chip. These values below just seem to
> + *       work well enough.
> + */
> +static const struct reg_sequence it6251_lvds_rx_sequence[] = {
> +	{ 0x05, 0x00 },
> +
> +	{ 0x3b, 0x42 },	/* reset LVDSRX PLL */
> +	{ 0x3b, 0x43 },
> +
> +	{ 0x3c, 0x08 },	/* something with SSC PLL */
> +	{ 0x0b, 0x88 },	/* don't swap links, writing reserved regs */
> +
> +	{ 0x2c, 0x01 },	/* JEIDA, 8-bit depth 0x11, original 0x42 */
> +	{ 0x32, 0x04 },	/* "reserved" */
> +	{ 0x35, 0xe0 },	/* "reserved" */
> +	{ 0x2b, 0x24 },	/* "reserved" + clock delay */
> +
> +	{ 0x05, 0x02 },	/* reset LVDSRX pix clock */
> +	{ 0x05, 0x00 },
> +};
> +
> +static const struct reg_sequence it6251_edp_tx_sequence[] = {
> +	/* two lane mode, normal operation, no swapping, no downspread */
> +	{ 0x16, 0x02 },
> +	{ 0x23, 0x40 },	/* some AUX channel EDID magic */
> +	{ 0x5c, 0xf3 },	/* power down lanes 3-0 */
> +	{ 0x5f, 0x06 },	/* enable DP scrambling, change EQ CR phase */
> +	{ 0x60, 0x02 },	/* color mode RGB, pclk/2 */
> +	{ 0x61, 0x04 },	/* dual pixel input mode, no EO swap, no RGB swap */
> +	{ 0x62, 0x01 },	/* M444B24 video format */
> +
> +	/* vesa range / not interlace / vsync high / hsync high */
> +	{ 0xa0, 0x0F },
> +
> +	{ 0xc9, 0xf5 },	/* hpd event timer set to 1.6-ish ms */
> +
> +	{ 0xca, 0x4d },	/* more reserved magic */
> +	{ 0xcb, 0x37 },
> +
> +	/* enhanced framing mode, auto video fifo reset, video mute disable */
> +	{ 0xd3, 0x03 },
> +	{ 0xd4, 0x45 },	/* "vidstmp" and some reserved stuff */
> +
> +	{ 0xe7, 0xa0 },	/* queue number -- reserved */
> +	{ 0xe8, 0x33 },	/* info frame packets and reserved */
> +	{ 0xec, 0x00 },	/* more AVI stuff */
> +
> +	{ 0x23, 0x42 },	/* select PC master reg for aux channel? */
> +
> +	{ 0x24, 0x00 },	/* send PC request commands */
> +	{ 0x25, 0x00 },
> +	{ 0x26, 0x00 },
> +
> +	{ 0x2b, 0x00 },	/* native aux read */
> +	{ 0x23, 0x40 },	/* back to internal */
> +
> +	{ 0x19, 0xff },	/* voltage swing level 3 */
> +	{ 0x1a, 0xff },	/* pre-emphasis level 3 */
> +
> +	{ 0x17, 0x01 },	/* start link training */
> +};
> +
> +static struct it6251_bridge *bridge_to_it6251(struct drm_bridge *bridge)
> +{
> +	return container_of(bridge, struct it6251_bridge, bridge);
> +}
> +
> +static struct it6251_bridge *conn_to_it6251(struct drm_connector *connector)
> +{
> +	return container_of(connector, struct it6251_bridge, connector);
> +}
> +
> +static int it6251_is_stable(struct it6251_bridge *it6251)
> +{
> +	unsigned int status, rpclkcnt, clkcnt, refstate, rpcreq;
> +	u16 hactive;
> +	u16 vactive;
> +	u8 regs[2];
> +	int ret;
> +
> +	ret = regmap_read(it6251->regmap, IT6251_SYSTEM_STATUS, &status);
> +	if (ret)
> +		return ret;
> +	dev_dbg(&it6251->client->dev, "System status: 0x%02x\n", status);
> +
> +	if (!(status & IT6251_SYSTEM_STATUS_RVIDEOSTABLE))
> +		return -EINVAL;
> +
> +	ret = regmap_bulk_read(it6251->regmap, IT6251_RPCLK_CNT_LOW, regs, 2);
> +	if (ret)
> +		return ret;
> +	rpclkcnt = (regs[0] & 0xff) | ((regs[1] & 0x0f) << 8);
> +	dev_dbg(&it6251->client->dev, "RPCLKCnt: %d\n", rpclkcnt);
> +
> +	ret = regmap_bulk_read(it6251->lvds_regmap, IT6251_PCLK_CNT_LOW,
> +			       regs, 2);
> +	if (ret)
> +		return ret;
> +	clkcnt = (regs[0] & 0xff) | ((regs[1] & 0x0f) << 8);
> +	dev_dbg(&it6251->client->dev, "Clock: 0x%02x\n", clkcnt);
> +
> +	ret = regmap_read(it6251->lvds_regmap, IT6251_REF_STATE, &refstate);
> +	if (ret)
> +		return ret;
> +	dev_dbg(&it6251->client->dev, "Ref Link State: 0x%02x\n", refstate);
> +
> +	ret = regmap_read(it6251->lvds_regmap, IT6251_RPC_REQ, &rpcreq);
> +	if (ret)
> +		return ret;
> +	dev_dbg(&it6251->client->dev, "RPC Req: 0x%02x\n", rpcreq);
> +
> +	ret = regmap_bulk_read(it6251->regmap, IT6251_DPHDEW_LOW, regs, 2);
> +	if (ret)
> +		return ret;
> +	hactive = (regs[0] & 0xff) | ((regs[1] & 0x1f) << 8);
> +	dev_dbg(&it6251->client->dev, "hactive: %d\n", hactive);
> +
> +	ret = regmap_bulk_read(it6251->regmap, IT6251_DPVDEW_LOW, regs, 2);
> +	if (ret)
> +		return ret;
> +	vactive = (regs[0] & 0xff) | ((regs[1] & 0x0f) << 8);
> +	dev_dbg(&it6251->client->dev, "vactive: %d\n", vactive);
> +
> +	if ((refstate & 0x1f) != 0)
> +		return -EINVAL;
> +
> +	if (rpcreq & IT6251_RPC_REQ_RPC_FIFOFULL) {
> +		dev_err(&it6251->client->dev,
> +			"RPC fifofull is set, might be an error\n");
> +		return -EINVAL;
> +	}
> +
> +	/* If video is muted, that's a failure */
> +	if (refstate & IT6251_REF_STATE_MUTED)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int it6251_init(struct it6251_bridge *it6251)
> +{
> +	const struct reg_sequence it6251_reset_reg_sequence[] = {
> +		{ 0x05, 0x00 },
> +		{ IT6251_LVDS_PORT_ADDR, it6251->lvds_client->addr << 1 },
> +		{ IT6251_LVDS_PORT_CTRL, IT6251_LVDS_PORT_CTRL_EN },
> +	};
> +
> +	int ret, stable_delays;
> +	unsigned int reg;
> +
> +	/*
> +	 * Reset DisplayPort half. Setting bit 2 causes IT6251 to not
> +	 * respond over i2c, which is considered "normal". This write
> +	 * will report failure, but will actually succeed.
> +	 */
> +	regmap_write(it6251->regmap, 0x05, 0xff);
> +
> +	/* Un-reset DisplayPort half and configure LVDS receiver. */
> +	ret = regmap_multi_reg_write(it6251->regmap, it6251_reset_reg_sequence,
> +				     ARRAY_SIZE(it6251_reset_reg_sequence));
> +	if (ret) {
> +		dev_err(&it6251->client->dev, "cannot setup eDP half\n");
> +		return ret;
> +	}
> +
> +	/* LVDS RX */
> +	regmap_write(it6251->lvds_regmap, 0x05, 0xff);
> +	ret = regmap_multi_reg_write(it6251->lvds_regmap,
> +				     it6251_lvds_rx_sequence,
> +				     ARRAY_SIZE(it6251_lvds_rx_sequence));
> +	if (ret) {
> +		dev_err(&it6251->lvds_client->dev, "cannot setup LVDS RX\n");
> +		return ret;
> +	}
> +
> +	/* eDP TX */
> +	ret = regmap_multi_reg_write(it6251->regmap,
> +				     it6251_edp_tx_sequence,
> +				     ARRAY_SIZE(it6251_edp_tx_sequence));
> +	if (ret) {
> +		dev_err(&it6251->client->dev, "cannot setup eDP TX\n");
> +		return ret;
> +	}
> +
> +	for (stable_delays = 0; stable_delays < 100; stable_delays++) {
> +		ret = regmap_read(it6251->regmap, 0x0e, &reg);
> +		if (ret || ((reg & 0x1f) != 0x10)) {
> +			mdelay(2);
> +			continue;
> +		}
> +
> +		ret = regmap_read(it6251->regmap, IT6251_SYSTEM_STATUS, &reg);
> +		if (ret || !(reg & IT6251_SYSTEM_STATUS_RVIDEOSTABLE)) {
> +			mdelay(2);
> +			continue;
> +		}
> +
> +		break;
> +	}
> +
> +	/*
> +	 * If we couldn't stabilize, requeue and try again, because it means
> +	 * that the LVDS channel isn't stable yet.
> +	 */
> +	ret = it6251_is_stable(it6251);
> +	if (ret)
> +		dev_err(&it6251->client->dev, "bridge is not stable\n");
> +
> +	return ret;
> +}
> +
> +static int it6251_power_down(struct it6251_bridge *it6251)
> +{
> +	struct device *dev = &it6251->client->dev;
> +	int ret = 0;
> +
> +	if (regulator_is_enabled(it6251->regulator)) {
> +		ret = regulator_disable(it6251->regulator);
> +		if (ret)
> +			dev_err(dev, "unable to disable regulator\n");
> +	}
> +
> +	return ret;
> +}
> +
> +static int it6251_power_up(struct it6251_bridge *it6251)
> +{
> +	struct i2c_client *client = it6251->client;
> +	u8 regs[4];
> +	int i, ret;
> +
> +	ret = regulator_enable(it6251->regulator);
> +	if (ret) {
> +		dev_err(&client->dev, "unable to enable regulator\n");
> +		return ret;
> +	}
> +
> +	/* Sometimes it seems like multiple tries are needed */
> +	for (i = 0; i < 5; i++) {
> +		ret = regmap_bulk_read(it6251->regmap, IT6251_VENDOR_ID_LOW,
> +				       regs, 4);
> +		if (!ret && regs[0] && regs[1] && regs[2] && regs[3]) {
> +			dev_info(&client->dev, "found ITE6251 [%04x:%04x]\n",
> +				 (regs[1] << 8) | regs[0],
> +				 (regs[3] << 8) | regs[2]);
> +			return 0;
> +		}
> +
> +		usleep_range(100000, 200000);
> +	}
> +
> +	dev_err(&client->dev, "unable to read product id\n");
> +	it6251_power_down(it6251);
> +	return -EINVAL;
> +}
> +
> +/* I2C driver functions */
> +static void it6251_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct it6251_bridge *it6251 = bridge_to_it6251(bridge);
> +
> +	if (drm_panel_prepare(it6251->panel)) {
> +		DRM_ERROR("failed to prepare panel\n");
> +		return;
> +	}
> +
> +	it6251_power_up(it6251);
> +}
> +
> +static void it6251_enable(struct drm_bridge *bridge)
> +{
> +	struct it6251_bridge *it6251 = bridge_to_it6251(bridge);
> +	int tries, ret;
> +
> +	if (drm_panel_enable(it6251->panel)) {
> +		DRM_ERROR("failed to enable panel\n");
> +		return;
> +	}
> +
> +	for (tries = 0; tries < 5; tries++) {
> +		ret = it6251_init(it6251);
> +		if (!ret)
> +			return;
> +
> +		/* If the init failed, restart the chip */
> +		it6251_power_down(it6251);
> +		it6251_power_up(it6251);
> +	}
> +}
> +
> +static void it6251_disable(struct drm_bridge *bridge)
> +{
> +	struct it6251_bridge *it6251 = bridge_to_it6251(bridge);
> +
> +	if (drm_panel_disable(it6251->panel))
> +		DRM_ERROR("failed to disable panel\n");
> +}
> +
> +static void it6251_post_disable(struct drm_bridge *bridge)
> +{
> +	struct it6251_bridge *it6251 = bridge_to_it6251(bridge);
> +
> +	if (drm_panel_unprepare(it6251->panel))
> +		DRM_ERROR("failed to unprepare panel\n");
> +
> +	it6251_power_down(it6251);
> +}
> +
> +static int it6251_get_modes(struct drm_connector *connector)
> +{
> +	struct it6251_bridge *it6251 = conn_to_it6251(connector);
> +
> +	return drm_panel_get_modes(it6251->panel, connector);
> +}
> +
> +static const struct drm_connector_helper_funcs it6251_connector_helper_funcs = {
> +	.get_modes	= it6251_get_modes,
> +};
> +
> +static const struct drm_connector_funcs it6251_connector_funcs = {
> +	.fill_modes		= drm_helper_probe_single_connector_modes,
> +	.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 int it6251_attach(struct drm_bridge *bridge, enum drm_bridge_attach_flags flags)
> +{
> +	struct it6251_bridge *it6251 = bridge_to_it6251(bridge);
> +	int ret;
> +

New bridge drivers need to support the DRM_BRIDGE_ATTACH_NO_CONNECTOR
flag, and implement the connector-related drm_bridge_funcs operations.
See the "[PATCH v2 0/21] drm/bridge: support drm bridge connector helper
+ panel updates" patch series on the dri-devel mailing list for
examples.

> +	if (!bridge->encoder) {
> +		DRM_ERROR("Parent encoder object not found");
> +		return -ENODEV;
> +	}
> +
> +	it6251->connector.polled = DRM_CONNECTOR_POLL_HPD;
> +	ret = drm_connector_init(bridge->dev, &it6251->connector,
> +				 &it6251_connector_funcs,
> +				 DRM_MODE_CONNECTOR_eDP);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialize connector with drm\n");
> +		return ret;
> +	}
> +
> +	drm_atomic_helper_connector_reset(&it6251->connector);
> +	drm_connector_helper_add(&it6251->connector,
> +				 &it6251_connector_helper_funcs);
> +	drm_connector_attach_encoder(&it6251->connector, bridge->encoder);
> +
> +	if (it6251->panel)
> +		drm_panel_attach(it6251->panel, &it6251->connector);
> +
> +	drm_helper_hpd_irq_event(it6251->connector.dev);
> +
> +	return 0;
> +}
> +
> +static const struct drm_bridge_funcs it6251_bridge_funcs = {
> +	.pre_enable	= it6251_pre_enable,
> +	.enable		= it6251_enable,
> +	.disable	= it6251_disable,
> +	.post_disable	= it6251_post_disable,
> +	.attach		= it6251_attach,
> +};
> +
> +static const struct regmap_config it6251_regmap_config = {
> +	.reg_bits	= 8,
> +	.val_bits	= 8,
> +	.max_register	= 0xff,
> +	.cache_type	= REGCACHE_NONE,
> +};
> +
> +static int
> +it6251_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct it6251_bridge *it6251;
> +	struct device_node *endpoint, *panel_node;
> +	int ret;
> +
> +	it6251 = devm_kzalloc(dev, sizeof(*it6251), GFP_KERNEL);
> +	if (!it6251)
> +		return -ENOMEM;
> +
> +	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
> +	if (endpoint) {
> +		panel_node = of_graph_get_remote_port_parent(endpoint);
> +		if (panel_node) {
> +			it6251->panel = of_drm_find_panel(panel_node);
> +			of_node_put(panel_node);
> +			if (!it6251->panel)
> +				return -EPROBE_DEFER;
> +		}
> +	}
> +
> +	it6251->client = client;
> +
> +	it6251->regmap = devm_regmap_init_i2c(client, &it6251_regmap_config);
> +	if (IS_ERR(it6251->regmap)) {
> +		dev_err(dev, "cannot init i2c regmap for IT6251\n");
> +		return PTR_ERR(it6251->regmap);
> +	}
> +
> +	it6251->regulator = devm_regulator_get(dev, "power");
> +	if (IS_ERR(it6251->regulator)) {
> +		dev_err(dev, "no power regulator found for IT6251\n");
> +		return PTR_ERR(it6251->regulator);
> +	}
> +
> +	/* The LVDS-half of the chip shows up at address 0x5e */
> +	it6251->lvds_client = i2c_new_ancillary_device(client, "lvds", 0x5e);
> +	if (IS_ERR(it6251->lvds_client)) {
> +		dev_err(dev, "cannot create I2C device for IT6251 LVDS\n");
> +		return PTR_ERR(it6251->lvds_client);
> +	}
> +
> +	it6251->lvds_regmap = regmap_init_i2c(it6251->lvds_client,
> +					      &it6251_regmap_config);
> +	if (IS_ERR(it6251->lvds_regmap)) {
> +		dev_err(dev, "cannot init i2c regmap for IT6251 LVDS\n");
> +		ret = PTR_ERR(it6251->lvds_regmap);
> +		goto err_lvds_regmap;
> +	}
> +
> +	i2c_set_clientdata(client, it6251);
> +
> +	it6251->bridge.funcs = &it6251_bridge_funcs;
> +	it6251->bridge.of_node = dev->of_node;
> +	drm_bridge_add(&it6251->bridge);
> +
> +	return 0;
> +
> +err_lvds_regmap:
> +	i2c_unregister_device(it6251->lvds_client);
> +	return ret;
> +}
> +
> +static int it6251_remove(struct i2c_client *client)
> +{
> +	struct it6251_bridge *it6251 = i2c_get_clientdata(client);
> +	int ret;
> +
> +	ret = it6251_power_down(it6251);
> +	if (ret)
> +		return ret;
> +
> +	regmap_exit(it6251->lvds_regmap);
> +	i2c_unregister_device(it6251->lvds_client);
> +
> +	return 0;
> +}
> +
> +static int it6251_pm_suspend(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct it6251_bridge *it6251 = i2c_get_clientdata(client);
> +
> +	return it6251_power_down(it6251);
> +}
> +
> +static int it6251_pm_resume(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct it6251_bridge *it6251 = i2c_get_clientdata(client);
> +
> +	return it6251_power_up(it6251);
> +}
> +
> +static const struct dev_pm_ops it6251_dev_pm_ops = {
> +	.suspend = it6251_pm_suspend,
> +	.resume = it6251_pm_resume,
> +	.restore = it6251_pm_resume,
> +};
> +
> +static struct i2c_device_id it6251_ids[] = {
> +	{ "it6251", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, it6251_ids);
> +
> +static const struct of_device_id it6251_of_match[] = {
> +	{ .compatible = "ite,it6251", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, it6251_of_match);
> +
> +static struct i2c_driver it6251_driver = {
> +	.driver = {
> +		.name		= "it6251",
> +		.pm		= &it6251_dev_pm_ops,
> +		.of_match_table	= it6251_of_match,
> +	},
> +	.probe		= it6251_probe,
> +	.remove		= it6251_remove,
> +	.id_table	= it6251_ids,
> +};
> +
> +module_i2c_driver(it6251_driver);
> +
> +/* Module initialization */
> +MODULE_AUTHOR("Sean Cross <xobs@kosagi.com>");
> +MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
> +MODULE_DESCRIPTION("ITE Tech 6251 LVDS to DisplayPort encoder");
> +MODULE_LICENSE("GPL");

-- 
Regards,

Laurent Pinchart