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Date:   Wed, 1 Jul 2020 11:35:57 +0200
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Vinay Simha BN <simhavcs@gmail.com>
Cc:     narmstrong@baylibre.com, Ken-Sue.Tan@taec.toshiba.com,
        Chris.Cheng@taec.toshiba.com, Bhushan.Patel@taec.toshiba.com,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Jonas Karlman <jonas@kwiboo.se>,
        David Airlie <airlied@linux.ie>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH v5 2/2] display/drm/bridge: TC358775 DSI/LVDS driver
Message-ID: <20200701093557.GC266726@ravnborg.org>
References: <20200701070344.6330-1-simhavcs@gmail.com>
 <20200701070344.6330-2-simhavcs@gmail.com>
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In-Reply-To: <20200701070344.6330-2-simhavcs@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Vinay.

On Wed, Jul 01, 2020 at 12:33:37PM +0530, Vinay Simha BN wrote:

Please provide some kind of changlog.
for example info where this bridge is used.


> Signed-off-by: Vinay Simha BN <simhavcs@gmail.com>

Some comments in the following.

	Sam

> 
> ---
> v1:
>  Initial version
> 
> v2:
> * Andrzej Hajda review comments incorporated
>   SPDX identifier
>   development debug removed
>   alphabetic order headers
>   u32 instead of unit32_t
>   magic numbers to macros for CLRSI and mux registers
>   ignored return value
> 
> * Laurent Pinchart review comments incorporated
>   mdelay to usleep_range
>   bus_formats added
> 
> v3:
> * Andrzej Hajda review comments incorporated
>   drm_connector_status removed
>   u32 rev removed and local variabl is used
>   regulator enable disable with proper orders and delays
>   as per the spec
>   devm_drm_panel_bridge_add method used instead of panel
>   description modified
>   dual port implemented
> 
> v4:
> * Sam Ravnborg review comments incorporated
>   panel->connector_type removed
> 
> * Reported-by: kernel test robot <lkp@intel.com>
>   parse_dt to static function
>   removed the if (endpoint), since data-lanes has to be
>   present for dsi dts ports
> 
> v5:
>   ~vsdelay dynamic value set based on the
>   calculation of dsi speed, output speed, blanking
> ---
>  drivers/gpu/drm/bridge/Kconfig    |  10 +
>  drivers/gpu/drm/bridge/Makefile   |   1 +
>  drivers/gpu/drm/bridge/tc358775.c | 735 ++++++++++++++++++++++++++++++
>  3 files changed, 746 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/tc358775.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 43271c21d3fc..084e9853944a 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -181,6 +181,16 @@ config DRM_TOSHIBA_TC358768
>  	help
>  	  Toshiba TC358768AXBG/TC358778XBG DSI bridge chip driver.
>  
> +config DRM_TOSHIBA_TC358775
> +        tristate "Toshiba TC358775 LVDS bridge"
> +        depends on OF
> +        select DRM_KMS_HELPER
> +        select REGMAP_I2C
> +        select DRM_PANEL
> +	select DRM_MIPI_DSI
> +        ---help---
--help---
is no longer supported. Use plain "help".

> +          Toshiba TC358775 LVDS bridge chip driver.
This is a very short description. Can you elaborate more here?

> +
>  config DRM_TI_TFP410
>  	tristate "TI TFP410 DVI/HDMI bridge"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index d63d4b7e4347..23c770b3bfe4 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_DRM_THINE_THC63LVD1024) += thc63lvd1024.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358764) += tc358764.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358767) += tc358767.o
>  obj-$(CONFIG_DRM_TOSHIBA_TC358768) += tc358768.o
> +obj-$(CONFIG_DRM_TOSHIBA_TC358775) += tc358775.o
>  obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> diff --git a/drivers/gpu/drm/bridge/tc358775.c b/drivers/gpu/drm/bridge/tc358775.c
> new file mode 100644
> index 000000000000..e580c544190c
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/tc358775.c
> @@ -0,0 +1,735 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * tc358775 DSI to LVDS bridge driver
> + *
> + * Copyright (C) 2020 SMART Wireless Computing
> + * Author: Vinay Simha BN <simhavcs@gmail.com>
> + *
> + */
> +/* #define DEBUG */
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_crtc_helper.h>
> +#include <drm/drm_dp_helper.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> +#include <drm/drm_probe_helper.h>
> +
> +#define FLD_MASK(start, end)    (((1 << ((start) - (end) + 1)) - 1) << (end))
> +#define FLD_VAL(val, start, end) (((val) << (end)) & FLD_MASK(start, end))
> +
> +/* Registers */
> +
> +/* DSI D-PHY Layer Registers */
> +#define D0W_DPHYCONTTX  0x0004  /* Data Lane 0 DPHY Tx Control */
> +#define CLW_DPHYCONTRX  0x0020  /* Clock Lane DPHY Rx Control */
> +#define D0W_DPHYCONTRX  0x0024  /* Data Lane 0 DPHY Rx Control */
> +#define D1W_DPHYCONTRX  0x0028  /* Data Lane 1 DPHY Rx Control */
> +#define D2W_DPHYCONTRX  0x002C  /* Data Lane 2 DPHY Rx Control */
> +#define D3W_DPHYCONTRX  0x0030  /* Data Lane 3 DPHY Rx Control */
> +#define COM_DPHYCONTRX  0x0038  /* DPHY Rx Common Control */
> +#define CLW_CNTRL       0x0040  /* Clock Lane Control */
> +#define D0W_CNTRL       0x0044  /* Data Lane 0 Control */
> +#define D1W_CNTRL       0x0048  /* Data Lane 1 Control */
> +#define D2W_CNTRL       0x004C  /* Data Lane 2 Control */
> +#define D3W_CNTRL       0x0050  /* Data Lane 3 Control */
> +#define DFTMODE_CNTRL   0x0054  /* DFT Mode Control */
> +
> +/* DSI PPI Layer Registers */
> +#define PPI_STARTPPI    0x0104  /* START control bit of PPI-TX function. */
> +#define PPI_START_FUNCTION      1
> +
> +#define PPI_BUSYPPI     0x0108
> +#define PPI_LINEINITCNT 0x0110  /* Line Initialization Wait Counter  */
> +#define PPI_LPTXTIMECNT 0x0114
> +#define PPI_LANEENABLE  0x0134  /* Enables each lane at the PPI layer. */
> +#define PPI_TX_RX_TA    0x013C  /* DSI Bus Turn Around timing parameters */
> +
> +/* Analog timer function enable */
> +#define PPI_CLS_ATMR    0x0140  /* Delay for Clock Lane in LPRX  */
> +#define PPI_D0S_ATMR    0x0144  /* Delay for Data Lane 0 in LPRX */
> +#define PPI_D1S_ATMR    0x0148  /* Delay for Data Lane 1 in LPRX */
> +#define PPI_D2S_ATMR    0x014C  /* Delay for Data Lane 2 in LPRX */
> +#define PPI_D3S_ATMR    0x0150  /* Delay for Data Lane 3 in LPRX */
> +
> +#define PPI_D0S_CLRSIPOCOUNT    0x0164  /* For lane 0 */
> +#define PPI_D1S_CLRSIPOCOUNT    0x0168  /* For lane 1 */
> +#define PPI_D2S_CLRSIPOCOUNT    0x016C  /* For lane 2 */
> +#define PPI_D3S_CLRSIPOCOUNT    0x0170  /* For lane 3 */
> +
> +#define CLS_PRE         0x0180  /* Digital Counter inside of PHY IO */
> +#define D0S_PRE         0x0184  /* Digital Counter inside of PHY IO */
> +#define D1S_PRE         0x0188  /* Digital Counter inside of PHY IO */
> +#define D2S_PRE         0x018C  /* Digital Counter inside of PHY IO */
> +#define D3S_PRE         0x0190  /* Digital Counter inside of PHY IO */
> +#define CLS_PREP        0x01A0  /* Digital Counter inside of PHY IO */
> +#define D0S_PREP        0x01A4  /* Digital Counter inside of PHY IO */
> +#define D1S_PREP        0x01A8  /* Digital Counter inside of PHY IO */
> +#define D2S_PREP        0x01AC  /* Digital Counter inside of PHY IO */
> +#define D3S_PREP        0x01B0  /* Digital Counter inside of PHY IO */
> +#define CLS_ZERO        0x01C0  /* Digital Counter inside of PHY IO */
> +#define D0S_ZERO        0x01C4  /* Digital Counter inside of PHY IO */
> +#define D1S_ZERO        0x01C8  /* Digital Counter inside of PHY IO */
> +#define D2S_ZERO        0x01CC  /* Digital Counter inside of PHY IO */
> +#define D3S_ZERO        0x01D0  /* Digital Counter inside of PHY IO */
> +
> +#define PPI_CLRFLG      0x01E0  /* PRE Counters has reached set values */
> +#define PPI_CLRSIPO     0x01E4  /* Clear SIPO values, Slave mode use only. */
> +#define HSTIMEOUT       0x01F0  /* HS Rx Time Out Counter */
> +#define HSTIMEOUTENABLE 0x01F4  /* Enable HS Rx Time Out Counter */
> +#define DSI_STARTDSI    0x0204  /* START control bit of DSI-TX function */
> +#define DSI_RX_START	1
> +
> +#define DSI_BUSYDSI     0x0208
> +#define DSI_LANEENABLE  0x0210  /* Enables each lane at the Protocol layer. */
> +#define DSI_LANESTATUS0 0x0214  /* Displays lane is in HS RX mode. */
> +#define DSI_LANESTATUS1 0x0218  /* Displays lane is in ULPS or STOP state */
> +
> +#define DSI_INTSTATUS   0x0220  /* Interrupt Status */
> +#define DSI_INTMASK     0x0224  /* Interrupt Mask */
> +#define DSI_INTCLR      0x0228  /* Interrupt Clear */
> +#define DSI_LPTXTO      0x0230  /* Low Power Tx Time Out Counter */
> +
> +#define DSIERRCNT       0x0300  /* DSI Error Count */
> +#define APLCTRL         0x0400  /* Application Layer Control */
> +#define RDPKTLN         0x0404  /* Command Read Packet Length */
> +
> +#define VPCTRL          0x0450  /* Video Path Control */
> +#define HTIM1           0x0454  /* Horizontal Timing Control 1 */
> +#define HTIM2           0x0458  /* Horizontal Timing Control 2 */
> +#define VTIM1           0x045C  /* Vertical Timing Control 1 */
> +#define VTIM2           0x0460  /* Vertical Timing Control 2 */
> +#define VFUEN           0x0464  /* Video Frame Timing Update Enable */
> +#define VFUEN_EN	BIT(0)  /* Upload Enable */
> +
> +/* Mux Input Select for LVDS LINK Input */
> +#define LV_MX0003        0x0480  /* Bit 0 to 3 */
> +#define LV_MX0407        0x0484  /* Bit 4 to 7 */
> +#define LV_MX0811        0x0488  /* Bit 8 to 11 */
> +#define LV_MX1215        0x048C  /* Bit 12 to 15 */
> +#define LV_MX1619        0x0490  /* Bit 16 to 19 */
> +#define LV_MX2023        0x0494  /* Bit 20 to 23 */
> +#define LV_MX2427        0x0498  /* Bit 24 to 27 */
> +#define LV_MX(b0, b1, b2, b3)	(FLD_VAL(b0, 4, 0) | FLD_VAL(b1, 12, 8) | \
> +				FLD_VAL(b2, 20, 16) | FLD_VAL(b3, 28, 24))
> +
> +/* Input bit numbers used in mux registers */
> +enum {
> +	LVI_R0,
> +	LVI_R1,
> +	LVI_R2,
> +	LVI_R3,
> +	LVI_R4,
> +	LVI_R5,
> +	LVI_R6,
> +	LVI_R7,
> +	LVI_G0,
> +	LVI_G1,
> +	LVI_G2,
> +	LVI_G3,
> +	LVI_G4,
> +	LVI_G5,
> +	LVI_G6,
> +	LVI_G7,
> +	LVI_B0,
> +	LVI_B1,
> +	LVI_B2,
> +	LVI_B3,
> +	LVI_B4,
> +	LVI_B5,
> +	LVI_B6,
> +	LVI_B7,
> +	LVI_HS,
> +	LVI_VS,
> +	LVI_DE,
> +	LVI_L0
> +};
> +
> +#define LVCFG           0x049C  /* LVDS Configuration  */
> +#define LVPHY0          0x04A0  /* LVDS PHY 0 */
> +#define LV_PHY0_RST(v)          FLD_VAL(v, 22, 22) /* PHY reset */
> +#define LV_PHY0_IS(v)           FLD_VAL(v, 15, 14)
> +#define LV_PHY0_ND(v)           FLD_VAL(v, 4, 0) /* Frequency range select */
> +#define LV_PHY0_PRBS_ON(v)      FLD_VAL(v, 20, 16) /* Clock/Data Flag pins */
> +
> +#define LVPHY1          0x04A4  /* LVDS PHY 1 */
> +#define SYSSTAT         0x0500  /* System Status  */
> +#define SYSRST          0x0504  /* System Reset  */
> +
> +#define SYS_RST_I2CS	BIT(0) /* Reset I2C-Slave controller */
> +#define SYS_RST_I2CM	BIT(1) /* Reset I2C-Master controller */
> +#define SYS_RST_LCD	BIT(2) /* Reset LCD controller */
> +#define SYS_RST_BM	BIT(3) /* Reset Bus Management controller */
> +#define SYS_RST_DSIRX	BIT(4) /* Reset DSI-RX and App controller */
> +#define SYS_RST_REG	BIT(5) /* Reset Register module */
> +
> +/* GPIO Registers */
> +#define GPIOC           0x0520  /* GPIO Control  */
> +#define GPIOO           0x0524  /* GPIO Output  */
> +#define GPIOI           0x0528  /* GPIO Input  */
> +
> +/* I2C Registers */
> +#define I2CTIMCTRL      0x0540  /* I2C IF Timing and Enable Control */
> +#define I2CMADDR        0x0544  /* I2C Master Addressing */
> +#define WDATAQ          0x0548  /* Write Data Queue */
> +#define RDATAQ          0x054C  /* Read Data Queue */
> +
> +/* Chip ID and Revision ID Register */
> +#define IDREG           0x0580
> +
> +#define LPX_PERIOD		4
> +#define TTA_GET			0x40000
> +#define TTA_SURE		6
> +
> +#define TC358775XBG_ID  0x00007500
> +
> +/* Debug Registers */
> +#define DEBUG00         0x05A0  /* Debug */
> +#define DEBUG01         0x05A4  /* LVDS Data */
> +
> +#define DSI_CLEN_BIT		BIT(0)
> +#define DIVIDE_BY_3		3 /* PCLK=DCLK/3 */
> +#define DIVIDE_BY_6		6 /* PCLK=DCLK/6 */
> +#define LVCFG_LVEN_BIT		BIT(0)
> +
> +#define L0EN BIT(1)
> +
> +#define TC358775_VPCTRL_VSDELAY__MASK	0x3FF00000
> +#define TC358775_VPCTRL_VSDELAY__SHIFT	20
> +static inline u32 TC358775_VPCTRL_VSDELAY(uint32_t val)
> +{
> +	return ((val) << TC358775_VPCTRL_VSDELAY__SHIFT) &
> +			TC358775_VPCTRL_VSDELAY__MASK;
> +}
> +
> +#define TC358775_VPCTRL_OPXLFMT__MASK	0x00000100
> +#define TC358775_VPCTRL_OPXLFMT__SHIFT	8
> +static inline u32 TC358775_VPCTRL_OPXLFMT(uint32_t val)
> +{
> +	return ((val) << TC358775_VPCTRL_OPXLFMT__SHIFT) &
> +			TC358775_VPCTRL_OPXLFMT__MASK;
> +}
> +
> +#define TC358775_VPCTRL_MSF__MASK	0x00000001
> +#define TC358775_VPCTRL_MSF__SHIFT	0
> +static inline u32 TC358775_VPCTRL_MSF(uint32_t val)
> +{
> +	return ((val) << TC358775_VPCTRL_MSF__SHIFT) &
> +			TC358775_VPCTRL_MSF__MASK;
> +}
> +
> +#define TC358775_LVCFG_PCLKDIV__MASK	0x000000f0
> +#define TC358775_LVCFG_PCLKDIV__SHIFT	4
> +static inline u32 TC358775_LVCFG_PCLKDIV(uint32_t val)
> +{
> +	return ((val) << TC358775_LVCFG_PCLKDIV__SHIFT) &
> +			TC358775_LVCFG_PCLKDIV__MASK;
> +}
> +
> +#define TC358775_LVCFG_LVDLINK__MASK                         0x00000002
> +#define TC358775_LVCFG_LVDLINK__SHIFT                        0
> +static inline u32 TC358775_LVCFG_LVDLINK(uint32_t val)
> +{
> +	return ((val) << TC358775_LVCFG_LVDLINK__SHIFT) &
> +			TC358775_LVCFG_LVDLINK__MASK;
> +}
> +
> +enum tc358775_ports {
> +	TC358775_DSI_IN,
> +	TC358775_LVDS_OUT0,
> +	TC358775_LVDS_OUT1,
> +};
> +
> +struct tc_data {
> +	struct i2c_client	*i2c;
> +	struct device		*dev;
> +
> +	struct drm_bridge	bridge;
> +	struct drm_bridge	*panel_bridge;
> +
> +	struct device_node *host_node;
> +	struct mipi_dsi_device *dsi;
> +	u8 num_dsi_lanes;
> +
> +	struct regulator	*vdd;
> +	struct regulator	*vddio;
> +	struct gpio_desc	*reset_gpio;
> +	struct gpio_desc	*stby_gpio;
> +	bool                    dual_link; /* single-link or dual-link */
> +};
> +
> +static inline struct tc_data *bridge_to_tc(struct drm_bridge *b)
> +{
> +	return container_of(b, struct tc_data, bridge);
> +}
> +
> +static void tc_bridge_pre_enable(struct drm_bridge *bridge)
> +{
> +	struct tc_data *tc = bridge_to_tc(bridge);
> +	struct device *dev = &tc->dsi->dev;
> +	int ret;
> +
> +	ret = regulator_enable(tc->vddio);
> +	if (ret < 0)
> +		dev_err(dev, "regulator vddio enable failed, %d\n", ret);
> +	usleep_range(10000, 11000);
> +
> +	ret = regulator_enable(tc->vdd);
> +	if (ret < 0)
> +		dev_err(dev, "regulator vdd enable failed, %d\n", ret);
> +	usleep_range(10000, 11000);
> +
> +	gpiod_set_value(tc->stby_gpio, 0);
> +	usleep_range(10000, 11000);
> +
> +	gpiod_set_value(tc->reset_gpio, 0);
> +	usleep_range(10, 20);
> +}
> +
> +static void tc_bridge_post_disable(struct drm_bridge *bridge)
> +{
> +	struct tc_data *tc = bridge_to_tc(bridge);
> +	struct device *dev = &tc->dsi->dev;
> +	int ret;
> +
> +	ret = regulator_disable(tc->vddio);
> +	if (ret < 0)
> +		dev_err(dev, "regulator vddio disable failed, %d\n", ret);
> +	usleep_range(10000, 11000);
> +
> +	ret = regulator_disable(tc->vdd);
> +	if (ret < 0)
> +		dev_err(dev, "regulator vdd disable failed, %d\n", ret);
> +	usleep_range(10000, 11000);
> +
> +	gpiod_set_value(tc->stby_gpio, 1);
> +	usleep_range(10000, 11000);
> +
> +	gpiod_set_value(tc->reset_gpio, 1);
> +	usleep_range(10, 20);
> +}
> +
> +static u32 d2l_read(struct i2c_client *i2c, u16 reg)
> +{
> +	int ret;
> +	u8 val[4];
> +	u8 addr[] = {(reg >> 8) & 0xff, reg & 0xff};
> +	u32 value;
> +
> +	ret = i2c_master_send(i2c, addr, sizeof(reg));
> +	if (ret < 0)
> +		goto fail;
> +
> +	ret = i2c_master_recv(i2c, val, sizeof(value));
> +	if (ret < 0)
> +		goto fail;
> +
> +	value = val[3] << 24 | val[2] << 16 | val[1] << 8 | val[0];
> +
> +	pr_debug("d2l: I2C : reg:%04x value:%08x\n", reg, value);
> +
> +	return value;
> +
> +fail:
> +	dev_err(&i2c->dev, "Error %d reading from subaddress 0x%x\n",
> +		ret, reg);
> +	return 0;
> +}
> +
> +static void d2l_write(struct i2c_client *i2c, u16 reg, u32 val)
> +{
> +	u8 buf[6];
> +	int ret;
> +
> +	buf[0] = reg >> 8;
> +	buf[1] = reg & 0xFF;
> +	buf[2] = (val >> 0) & 0xFF;
> +	buf[3] = (val >> 8) & 0xFF;
> +	buf[4] = (val >> 16) & 0xFF;
> +	buf[5] = (val >> 24) & 0xFF;
> +
> +	ret = i2c_master_send(i2c, buf, ARRAY_SIZE(buf));
> +	if (ret < 0)
> +		dev_err(&i2c->dev, "Error %d writing to subaddress 0x%x\n",
> +			ret, reg);
> +}
> +
> +/* helper function to access bus_formats */
> +static struct drm_connector *get_connector(struct drm_encoder *encoder)
> +{
> +	struct drm_device *dev = encoder->dev;
> +	struct drm_connector *connector;
> +
> +	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
> +		if (connector->encoder == encoder)
> +			return connector;
> +
> +	return NULL;
> +}
> +
> +static void tc_bridge_enable(struct drm_bridge *bridge)
> +{
> +	struct tc_data *tc = bridge_to_tc(bridge);
> +	u32 hbpr, hpw, htime1, hfpr, hsize, htime2;
> +	u32 vbpr, vpw, vtime1, vfpr, vsize, vtime2;
> +	u32 val = 0, val_lvcfg = 0;
> +	u16 dsiclk, clkdiv, byteclk, t1, t2, t3, vsdelay;
> +	u8 link, bpc;
> +	u16 bus_formats;
> +	struct drm_display_mode *mode;
> +	struct drm_connector *connector = get_connector(bridge->encoder);
> +
> +	mode = &bridge->encoder->crtc->state->adjusted_mode;
> +
> +	hbpr = mode->htotal - mode->hsync_end;
> +	hpw  = mode->hsync_end - mode->hsync_start;
> +	vbpr = mode->vtotal - mode->vsync_end;
> +	vpw  = mode->vsync_end - mode->vsync_start;
> +
> +	htime1 = (hbpr << 16) + hpw;
> +	vtime1 = (vbpr << 16) + vpw;
> +
> +	hfpr = mode->hsync_start - mode->hdisplay;
> +	hsize = mode->hdisplay;
> +	vfpr = mode->vsync_start - mode->vdisplay;
> +	vsize = mode->vdisplay;
> +
> +	htime2 = (hfpr << 16) + hsize;
> +	vtime2 = (vfpr << 16) + vsize;

If the local variables here used the same names as used in struct
display_timings then this would be ore readable.
vfpr is less readable compared to vfront_porch - especially because the
latter is well known names.

> +
> +	val = d2l_read(tc->i2c, IDREG);
> +
> +	dev_info(tc->dev, "DSI2LVDS Chip ID.%02x Revision ID. %02x **\n",
> +		 (val >> 8) & 0xFF, val & 0xFF);
> +
> +	d2l_write(tc->i2c, SYSRST, SYS_RST_REG | SYS_RST_DSIRX | SYS_RST_BM |
> +		  SYS_RST_LCD | SYS_RST_I2CM | SYS_RST_I2CS);
> +	usleep_range(30000, 40000);
> +
> +	d2l_write(tc->i2c, PPI_TX_RX_TA, TTA_GET | TTA_SURE);
> +	d2l_write(tc->i2c, PPI_LPTXTIMECNT, LPX_PERIOD);
> +	d2l_write(tc->i2c, PPI_D0S_CLRSIPOCOUNT, 3);
> +	d2l_write(tc->i2c, PPI_D1S_CLRSIPOCOUNT, 3);
> +	d2l_write(tc->i2c, PPI_D2S_CLRSIPOCOUNT, 3);
> +	d2l_write(tc->i2c, PPI_D3S_CLRSIPOCOUNT, 3);
> +
> +	val = ((L0EN << tc->num_dsi_lanes) - L0EN) | DSI_CLEN_BIT;
> +	d2l_write(tc->i2c, PPI_LANEENABLE, val);
> +	d2l_write(tc->i2c, DSI_LANEENABLE, val);
> +
> +	d2l_write(tc->i2c, PPI_STARTPPI, PPI_START_FUNCTION);
> +	d2l_write(tc->i2c, DSI_STARTDSI, DSI_RX_START);
> +
> +	val_lvcfg = LVCFG_LVEN_BIT;
> +	if (tc->dual_link) {
> +		link = 2;
> +		val_lvcfg |= TC358775_LVCFG_LVDLINK(1);
> +		val_lvcfg |= TC358775_LVCFG_PCLKDIV(DIVIDE_BY_6);
> +	} else {
> +		link = 1;
> +		val_lvcfg |= TC358775_LVCFG_PCLKDIV(DIVIDE_BY_3);
> +	}
> +
> +	bus_formats = connector->display_info.bus_formats[0];
> +	dev_dbg(tc->dev, "bus_formats : %04x\n", bus_formats);
> +
> +	if (bus_formats == MEDIA_BUS_FMT_RGB888_1X7X4_SPWG ||
> +	    bus_formats == MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA) {
> +		/* RGB888 */
> +		bpc = 8;
> +		val = TC358775_VPCTRL_OPXLFMT(1);
> +	} else {
> +		/* RGB666 */
> +		bpc = 6;
> +		val |= TC358775_VPCTRL_MSF(1);
> +	}
This code makes some assumptions about bus_format.
Maybe check for supported bus_format and error out if an unspupported
bus_format is found?
> +
> +	dsiclk = mode->crtc_clock * 3 * bpc / tc->num_dsi_lanes / 1000;
> +	clkdiv = dsiclk / DIVIDE_BY_3 * link;
> +	byteclk = dsiclk / 4;
> +	t1 = hsize * (bpc * 3 / 8) / tc->num_dsi_lanes;
> +	t2 = ((100000 / clkdiv)) * (hsize + hbpr + hpw + hfpr) / 1000;
> +	t3 = ((t2 * byteclk) / 100) - (hsize * (bpc * 3 / 8) /
> +		tc->num_dsi_lanes);
> +
> +	vsdelay = (clkdiv * (t1 + t3) / byteclk) - hbpr - hpw - hsize;
> +
> +	val |= TC358775_VPCTRL_VSDELAY(vsdelay);
> +	d2l_write(tc->i2c, VPCTRL, val);
> +
> +	d2l_write(tc->i2c, HTIM1, htime1);
> +	d2l_write(tc->i2c, VTIM1, vtime1);
> +	d2l_write(tc->i2c, HTIM2, htime2);
> +	d2l_write(tc->i2c, VTIM2, vtime2);
> +
> +	d2l_write(tc->i2c, VFUEN, VFUEN_EN);
> +	d2l_write(tc->i2c, SYSRST, SYS_RST_LCD);
> +	d2l_write(tc->i2c, LVPHY0, LV_PHY0_PRBS_ON(4) | LV_PHY0_ND(6));
> +
> +	/* default jeida-24 */
> +	if (bus_formats == MEDIA_BUS_FMT_RGB888_1X7X4_SPWG) {
> +		/* vesa-24 */
> +		d2l_write(tc->i2c, LV_MX0003, LV_MX(LVI_R0, LVI_R1, LVI_R2, LVI_R3));
> +		d2l_write(tc->i2c, LV_MX0407, LV_MX(LVI_R4, LVI_R7, LVI_R5, LVI_G0));
> +		d2l_write(tc->i2c, LV_MX0811, LV_MX(LVI_G1, LVI_G2, LVI_G6, LVI_G7));
> +		d2l_write(tc->i2c, LV_MX1215, LV_MX(LVI_G3, LVI_G4, LVI_G5, LVI_B0));
> +		d2l_write(tc->i2c, LV_MX1619, LV_MX(LVI_B6, LVI_B7, LVI_B1, LVI_B2));
> +		d2l_write(tc->i2c, LV_MX2023, LV_MX(LVI_B3, LVI_B4, LVI_B5, LVI_L0));
> +		d2l_write(tc->i2c, LV_MX2427, LV_MX(LVI_HS, LVI_VS, LVI_DE, LVI_R6));
> +	}
> +
> +	if (bus_formats == MEDIA_BUS_FMT_RGB666_1X7X3_SPWG) {
> +		/* jeida-18 */
> +		d2l_write(tc->i2c, LV_MX0003, LV_MX(LVI_R0, LVI_R1, LVI_R2, LVI_R3));
> +		d2l_write(tc->i2c, LV_MX0407, LV_MX(LVI_R4, LVI_L0, LVI_R5, LVI_G0));
> +		d2l_write(tc->i2c, LV_MX0811, LV_MX(LVI_G1, LVI_G2, LVI_L0, LVI_L0));
> +		d2l_write(tc->i2c, LV_MX1215, LV_MX(LVI_G3, LVI_G4, LVI_G5, LVI_B0));
> +		d2l_write(tc->i2c, LV_MX1619, LV_MX(LVI_L0, LVI_L0, LVI_B1, LVI_B2));
> +		d2l_write(tc->i2c, LV_MX2023, LV_MX(LVI_B3, LVI_B4, LVI_B5, LVI_L0));
> +		d2l_write(tc->i2c, LV_MX2427, LV_MX(LVI_HS, LVI_VS, LVI_DE, LVI_L0));
> +	}
MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA???

> +
> +	d2l_write(tc->i2c, VFUEN, VFUEN_EN);
> +	d2l_write(tc->i2c, LVCFG, val_lvcfg);
> +}
> +
> +static int tc_mode_valid(struct drm_bridge *bridge,
> +			 const struct drm_display_mode *mode)
> +{
> +	struct tc_data *tc = bridge_to_tc(bridge);
> +
> +	/* Maximum pixel clock speed 135MHz-single-link/270MHz-dual-link */
> +	if ((mode->clock > 135000 && tc->dual_link) ||
> +	    (mode->clock > 270000 && tc->dual_link))
> +		return MODE_CLOCK_HIGH;

I think this should read:
> +	if ((mode->clock > 135000 && !tc->dual_link) ||
Or maybe the comment is wrong and 135 Mhz is maximum with dual-link?

> +
> +	return MODE_OK;
> +}
> +
> +static int tc358775_parse_dt(struct device_node *np, struct tc_data *tc)
> +{
> +	struct device_node *endpoint;
> +	struct device_node *parent;
> +	struct device_node *remote;
> +	struct property *prop;
> +	int len;
> +
> +	endpoint = of_graph_get_endpoint_by_regs(tc->dev->of_node,
> +						 TC358775_DSI_IN, -1);
> +	if (endpoint) {
> +		/* dsi0_out node */
		TC358775_DSI_IN is port@0 whic is input.
	
> +		parent = of_graph_get_remote_port_parent(endpoint);
> +		of_node_put(endpoint);
> +		if (parent) {
> +			/* dsi0 port 1 */
> +			endpoint = of_graph_get_endpoint_by_regs(parent, 1, -1);
> +			of_node_put(parent);
> +			prop = of_find_property(endpoint, "data-lanes",
> +						&len);
> +			of_node_put(endpoint);
> +			if (!prop) {
> +				dev_err(tc->dev,
> +					"failed to find data lane\n");
> +				return -EPROBE_DEFER;
> +			}
> +		}
> +	}

Error handling looks wrong.
if endpoint is not set then len is never assigned.

> +	tc->num_dsi_lanes = len / sizeof(u32);
> +
> +	if (tc->num_dsi_lanes < 1 || tc->num_dsi_lanes > 4)
> +		return -EINVAL;
> +
> +	tc->host_node = of_graph_get_remote_node(np, 0, 0);
> +	if (!tc->host_node)
> +		return -ENODEV;
> +
> +	of_node_put(tc->host_node);
> +
> +	endpoint = of_graph_get_endpoint_by_regs(tc->dev->of_node,
> +						 TC358775_LVDS_OUT1, -1);
> +	if (endpoint) {
> +		remote = of_graph_get_remote_port_parent(endpoint);
> +		of_node_put(endpoint);
> +
> +		if (remote) {
> +			if (of_device_is_available(remote))
> +				tc->dual_link = true;
> +			of_node_put(remote);
> +		}
> +	}
> +
> +	dev_dbg(tc->dev, "no.of dsi lanes: %d\n", tc->num_dsi_lanes);
> +	dev_dbg(tc->dev, "operating in %s-link mode\n",
> +		tc->dual_link ? "dual" : "single");
> +
> +	return 0;
> +}
> +
> +static int tc_bridge_attach(struct drm_bridge *bridge,
> +			    enum drm_bridge_attach_flags flags)
> +{
> +	struct tc_data *tc = bridge_to_tc(bridge);
> +	struct device *dev = &tc->i2c->dev;
> +	struct mipi_dsi_host *host;
> +	struct mipi_dsi_device *dsi;
> +	int ret;
> +
> +	const struct mipi_dsi_device_info info = { .type = "tc358775",
> +							.channel = 0,
> +							.node = NULL,
> +						};
> +
> +	host = of_find_mipi_dsi_host_by_node(tc->host_node);
> +	if (!host) {
> +		dev_err(dev, "failed to find dsi host\n");
> +		return -EPROBE_DEFER;
> +	}
> +
> +	dsi = mipi_dsi_device_register_full(host, &info);
> +	if (IS_ERR(dsi)) {
> +		dev_err(dev, "failed to create dsi device\n");
> +		ret = PTR_ERR(dsi);
> +		goto err_dsi_device;
> +	}
> +
> +	tc->dsi = dsi;
> +
> +	dsi->lanes = tc->num_dsi_lanes;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to attach dsi to host\n");
> +		goto err_dsi_attach;
> +	}
> +
> +	/* Attach the panel-bridge to the dsi bridge */
> +	return drm_bridge_attach(bridge->encoder, tc->panel_bridge,
> +				 &tc->bridge, flags);
> +err_dsi_attach:
> +	mipi_dsi_device_unregister(dsi);
> +err_dsi_device:
> +	return ret;
> +}
> +
> +static const struct drm_bridge_funcs tc_bridge_funcs = {
> +	.attach = tc_bridge_attach,
> +	.pre_enable = tc_bridge_pre_enable,
> +	.enable = tc_bridge_enable,
> +	.mode_valid = tc_mode_valid,
> +	.post_disable = tc_bridge_post_disable,
> +};
> +
> +static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct drm_panel *panel;
> +	struct tc_data *tc;
> +	int ret;
> +
> +	tc = devm_kzalloc(dev, sizeof(*tc), GFP_KERNEL);
> +	if (!tc)
> +		return -ENOMEM;
> +
> +	tc->dev = dev;
> +	tc->i2c = client;
> +
> +	ret = drm_of_find_panel_or_bridge(dev->of_node, TC358775_LVDS_OUT0,
> +					  0, &panel, NULL);
> +	if (ret < 0)
> +		return ret;
> +	if (!panel)
> +		return -ENODEV;
> +
> +	tc->panel_bridge = devm_drm_panel_bridge_add(dev, panel);
> +	if (IS_ERR(tc->panel_bridge))
> +		return PTR_ERR(tc->panel_bridge);
> +
> +	ret = tc358775_parse_dt(dev->of_node, tc);
> +	if (ret)
> +		return ret;
> +
> +	tc->vddio = devm_regulator_get(dev, "vddio-supply");
> +	if (IS_ERR(tc->vddio)) {
> +		ret = PTR_ERR(tc->vddio);
> +		dev_err(dev, "vddio-supply not found\n");
> +		return ret;
> +	}
> +
> +	tc->vdd = devm_regulator_get(dev, "vdd-supply");
> +	if (IS_ERR(tc->vdd)) {
> +		ret = PTR_ERR(tc->vddio);
> +		dev_err(dev, "vdd-supply not found\n");
> +		return ret;
> +	}
> +
> +	tc->stby_gpio = devm_gpiod_get(dev, "stby", GPIOD_OUT_HIGH);
> +	if (IS_ERR(tc->stby_gpio)) {
> +		ret = PTR_ERR(tc->stby_gpio);
> +		dev_err(dev, "cannot get stby-gpio %d\n", ret);
> +		return ret;
> +	}
> +
> +	tc->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(tc->reset_gpio)) {
> +		ret = PTR_ERR(tc->reset_gpio);
> +		dev_err(dev, "cannot get reset-gpios %d\n", ret);
> +		return ret;
> +	}
> +
> +	tc->bridge.funcs = &tc_bridge_funcs;
> +	tc->bridge.of_node = dev->of_node;
> +	drm_bridge_add(&tc->bridge);
> +
> +	i2c_set_clientdata(client, tc);
> +
> +	return 0;
> +}
> +
> +static int tc_remove(struct i2c_client *client)
> +{
> +	struct tc_data *tc = i2c_get_clientdata(client);
> +
> +	drm_bridge_remove(&tc->bridge);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id tc358775_i2c_ids[] = {
> +	{ "tc358775", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, tc358775_i2c_ids);
> +
> +static const struct of_device_id tc358775_of_ids[] = {
> +	{ .compatible = "toshiba,tc358775", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, tc358775_of_ids);
> +
> +static struct i2c_driver tc358775_driver = {
> +	.driver = {
> +		.name = "tc358775",
> +		.of_match_table = tc358775_of_ids,
> +	},
> +	.id_table = tc358775_i2c_ids,
> +	.probe = tc_probe,
> +	.remove	= tc_remove,
> +};
> +module_i2c_driver(tc358775_driver);
> +
> +MODULE_AUTHOR("Vinay Simha BN <simhavcs@gmail.com>");
> +MODULE_DESCRIPTION("TC358775 DSI/LVDS bridge driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.17.1
> 
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