From mboxrd@z Thu Jan  1 00:00:00 1970
From: philippe.cornu@st.com (Philippe CORNU)
Date: Thu, 29 Jun 2017 14:43:27 +0000
Subject: [PATCH v4 3/6] drm/bridge/synopsys: Add MIPI DSI host controller
 bridge
In-Reply-To: <1aad8695-8527-574c-2b99-9efa88216aa8@codeaurora.org>
References: <1497889685-27349-1-git-send-email-philippe.cornu@st.com>
 <1497889685-27349-4-git-send-email-philippe.cornu@st.com>
 <1aad8695-8527-574c-2b99-9efa88216aa8@codeaurora.org>
Message-ID: <7ff83ef9-dfc1-6b05-ccf1-1637ed4f4bcc@st.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org



On 06/28/2017 08:44 AM, Archit Taneja wrote:
> 
> 
> On 06/19/2017 09:58 PM, Philippe CORNU wrote:
>> Add a Synopsys Designware MIPI DSI host DRM bridge driver, based on the
>> Rockchip version from rockchip/dw-mipi-dsi.c with phy & bridge APIs.
>>
>> Signed-off-by: Philippe CORNU <philippe.cornu@st.com>
>> ---
>>   drivers/gpu/drm/bridge/synopsys/Kconfig       |   6 +
>>   drivers/gpu/drm/bridge/synopsys/Makefile      |   2 +
>>   drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 976 
>> ++++++++++++++++++++++++++
>>   include/drm/bridge/dw_mipi_dsi.h              |  39 +
>>   4 files changed, 1023 insertions(+)
>>   create mode 100644 drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>>   create mode 100644 include/drm/bridge/dw_mipi_dsi.h
>>
>> diff --git a/drivers/gpu/drm/bridge/synopsys/Kconfig 
>> b/drivers/gpu/drm/bridge/synopsys/Kconfig
>> index 40d2827..f00ee26 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/Kconfig
>> +++ b/drivers/gpu/drm/bridge/synopsys/Kconfig
>> @@ -21,3 +21,9 @@ config DRM_DW_HDMI_I2S_AUDIO
>>       help
>>         Support the I2S Audio interface which is part of the Synopsys
>>         Designware HDMI block.
>> +
>> +config DRM_DW_MIPI_DSI
>> +    tristate
>> +    select DRM_KMS_HELPER
>> +    select DRM_MIPI_DSI
>> +    select DRM_PANEL_BRIDGE
>> diff --git a/drivers/gpu/drm/bridge/synopsys/Makefile 
>> b/drivers/gpu/drm/bridge/synopsys/Makefile
>> index 17aa7a6..5f57d36 100644
>> --- a/drivers/gpu/drm/bridge/synopsys/Makefile
>> +++ b/drivers/gpu/drm/bridge/synopsys/Makefile
>> @@ -3,3 +3,5 @@
>>   obj-$(CONFIG_DRM_DW_HDMI) += dw-hdmi.o
>>   obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw-hdmi-ahb-audio.o
>>   obj-$(CONFIG_DRM_DW_HDMI_I2S_AUDIO) += dw-hdmi-i2s-audio.o
>> +
>> +obj-$(CONFIG_DRM_DW_MIPI_DSI) += dw-mipi-dsi.o
>> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c 
>> b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> new file mode 100644
>> index 0000000..416ed7f
>> --- /dev/null
>> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
>> @@ -0,0 +1,976 @@
>> +/*
>> + * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
>> + * Copyright (C) STMicroelectronics SA 2017
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * Modified by Philippe Cornu <philippe.cornu@st.com>
>> + * This generic Synopsys DesignWare MIPI DSI host driver is based on the
>> + * Rockchip version from rockchip/dw-mipi-dsi.c with phy & bridge APIs.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/component.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/reset.h>
>> +#include <drm/drmP.h>
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_bridge.h>
>> +#include <drm/drm_crtc.h>
>> +#include <drm/drm_crtc_helper.h>
>> +#include <drm/drm_mipi_dsi.h>
>> +#include <drm/drm_of.h>
>> +#include <drm/bridge/dw_mipi_dsi.h>
>> +#include <video/mipi_display.h>
>> +
>> +#define DSI_VERSION            0x00
>> +#define DSI_PWR_UP            0x04
>> +#define RESET                0
>> +#define POWERUP                BIT(0)
>> +
>> +#define DSI_CLKMGR_CFG            0x08
>> +#define TO_CLK_DIVIDSION(div)        (((div) & 0xff) << 8)
>> +#define TX_ESC_CLK_DIVIDSION(div)    (((div) & 0xff) << 0)
>> +
>> +#define DSI_DPI_VCID            0x0c
>> +#define DPI_VID(vid)            (((vid) & 0x3) << 0)
>> +
>> +#define DSI_DPI_COLOR_CODING        0x10
>> +#define EN18_LOOSELY            BIT(8)
>> +#define DPI_COLOR_CODING_16BIT_1    0x0
>> +#define DPI_COLOR_CODING_16BIT_2    0x1
>> +#define DPI_COLOR_CODING_16BIT_3    0x2
>> +#define DPI_COLOR_CODING_18BIT_1    0x3
>> +#define DPI_COLOR_CODING_18BIT_2    0x4
>> +#define DPI_COLOR_CODING_24BIT        0x5
>> +
>> +#define DSI_DPI_CFG_POL            0x14
>> +#define COLORM_ACTIVE_LOW        BIT(4)
>> +#define SHUTD_ACTIVE_LOW        BIT(3)
>> +#define HSYNC_ACTIVE_LOW        BIT(2)
>> +#define VSYNC_ACTIVE_LOW        BIT(1)
>> +#define DATAEN_ACTIVE_LOW        BIT(0)
>> +
>> +#define DSI_DPI_LP_CMD_TIM        0x18
>> +#define OUTVACT_LPCMD_TIME(p)        (((p) & 0xff) << 16)
>> +#define INVACT_LPCMD_TIME(p)        ((p) & 0xff)
>> +
>> +#define DSI_DBI_CFG            0x20
>> +#define DSI_DBI_CMDSIZE            0x28
>> +
>> +#define DSI_PCKHDL_CFG            0x2c
>> +#define EN_CRC_RX            BIT(4)
>> +#define EN_ECC_RX            BIT(3)
>> +#define EN_BTA                BIT(2)
>> +#define EN_EOTP_RX            BIT(1)
>> +#define EN_EOTP_TX            BIT(0)
>> +
>> +#define DSI_MODE_CFG            0x34
>> +#define ENABLE_VIDEO_MODE        0
>> +#define ENABLE_CMD_MODE            BIT(0)
>> +
>> +#define DSI_VID_MODE_CFG        0x38
>> +#define FRAME_BTA_ACK            BIT(14)
>> +#define ENABLE_LOW_POWER        (0x3f << 8)
>> +#define ENABLE_LOW_POWER_MASK        (0x3f << 8)
>> +#define VID_MODE_TYPE_NON_BURST_SYNC_PULSES    0x0
>> +#define VID_MODE_TYPE_NON_BURST_SYNC_EVENTS    0x1
>> +#define VID_MODE_TYPE_BURST            0x2
>> +#define VID_MODE_TYPE_MASK            0x3
>> +
>> +#define DSI_VID_PKT_SIZE        0x3c
>> +#define VID_PKT_SIZE(p)            (((p) & 0x3fff) << 0)
>> +#define VID_PKT_MAX_SIZE        0x3fff
>> +
>> +#define DSI_VID_HSA_TIME        0x48
>> +#define DSI_VID_HBP_TIME        0x4c
>> +#define DSI_VID_HLINE_TIME        0x50
>> +#define DSI_VID_VSA_LINES        0x54
>> +#define DSI_VID_VBP_LINES        0x58
>> +#define DSI_VID_VFP_LINES        0x5c
>> +#define DSI_VID_VACTIVE_LINES        0x60
>> +#define DSI_CMD_MODE_CFG        0x68
>> +#define MAX_RD_PKT_SIZE_LP        BIT(24)
>> +#define DCS_LW_TX_LP            BIT(19)
>> +#define DCS_SR_0P_TX_LP            BIT(18)
>> +#define DCS_SW_1P_TX_LP            BIT(17)
>> +#define DCS_SW_0P_TX_LP            BIT(16)
>> +#define GEN_LW_TX_LP            BIT(14)
>> +#define GEN_SR_2P_TX_LP            BIT(13)
>> +#define GEN_SR_1P_TX_LP            BIT(12)
>> +#define GEN_SR_0P_TX_LP            BIT(11)
>> +#define GEN_SW_2P_TX_LP            BIT(10)
>> +#define GEN_SW_1P_TX_LP            BIT(9)
>> +#define GEN_SW_0P_TX_LP            BIT(8)
>> +#define EN_ACK_RQST            BIT(1)
>> +#define EN_TEAR_FX            BIT(0)
>> +
>> +#define CMD_MODE_ALL_LP            (MAX_RD_PKT_SIZE_LP | \
>> +                     DCS_LW_TX_LP | \
>> +                     DCS_SR_0P_TX_LP | \
>> +                     DCS_SW_1P_TX_LP | \
>> +                     DCS_SW_0P_TX_LP | \
>> +                     GEN_LW_TX_LP | \
>> +                     GEN_SR_2P_TX_LP | \
>> +                     GEN_SR_1P_TX_LP | \
>> +                     GEN_SR_0P_TX_LP | \
>> +                     GEN_SW_2P_TX_LP | \
>> +                     GEN_SW_1P_TX_LP | \
>> +                     GEN_SW_0P_TX_LP)
>> +
>> +#define DSI_GEN_HDR            0x6c
>> +#define GEN_HDATA(data)            (((data) & 0xffff) << 8)
>> +#define GEN_HDATA_MASK            (0xffff << 8)
>> +#define GEN_HTYPE(type)            (((type) & 0xff) << 0)
>> +#define GEN_HTYPE_MASK            0xff
>> +
>> +#define DSI_GEN_PLD_DATA        0x70
>> +
>> +#define DSI_CMD_PKT_STATUS        0x74
>> +#define GEN_CMD_EMPTY            BIT(0)
>> +#define GEN_CMD_FULL            BIT(1)
>> +#define GEN_PLD_W_EMPTY            BIT(2)
>> +#define GEN_PLD_W_FULL            BIT(3)
>> +#define GEN_PLD_R_EMPTY            BIT(4)
>> +#define GEN_PLD_R_FULL            BIT(5)
>> +#define GEN_RD_CMD_BUSY            BIT(6)
>> +
>> +#define DSI_TO_CNT_CFG            0x78
>> +#define HSTX_TO_CNT(p)            (((p) & 0xffff) << 16)
>> +#define LPRX_TO_CNT(p)            ((p) & 0xffff)
>> +
>> +#define DSI_BTA_TO_CNT            0x8c
>> +#define DSI_LPCLK_CTRL            0x94
>> +#define AUTO_CLKLANE_CTRL        BIT(1)
>> +#define PHY_TXREQUESTCLKHS        BIT(0)
>> +
>> +#define DSI_PHY_TMR_LPCLK_CFG        0x98
>> +#define PHY_CLKHS2LP_TIME(lbcc)        (((lbcc) & 0x3ff) << 16)
>> +#define PHY_CLKLP2HS_TIME(lbcc)        ((lbcc) & 0x3ff)
>> +
>> +#define DSI_PHY_TMR_CFG            0x9c
>> +#define PHY_HS2LP_TIME(lbcc)        (((lbcc) & 0xff) << 24)
>> +#define PHY_LP2HS_TIME(lbcc)        (((lbcc) & 0xff) << 16)
>> +#define MAX_RD_TIME(lbcc)        ((lbcc) & 0x7fff)
>> +
>> +#define DSI_PHY_RSTZ            0xa0
>> +#define PHY_DISFORCEPLL            0
>> +#define PHY_ENFORCEPLL            BIT(3)
>> +#define PHY_DISABLECLK            0
>> +#define PHY_ENABLECLK            BIT(2)
>> +#define PHY_RSTZ            0
>> +#define PHY_UNRSTZ            BIT(1)
>> +#define PHY_SHUTDOWNZ            0
>> +#define PHY_UNSHUTDOWNZ            BIT(0)
>> +
>> +#define DSI_PHY_IF_CFG            0xa4
>> +#define N_LANES(n)            ((((n) - 1) & 0x3) << 0)
>> +#define PHY_STOP_WAIT_TIME(cycle)    (((cycle) & 0xff) << 8)
>> +
>> +#define DSI_PHY_STATUS            0xb0
>> +#define LOCK                BIT(0)
>> +#define STOP_STATE_CLK_LANE        BIT(2)
>> +
>> +#define DSI_PHY_TST_CTRL0        0xb4
>> +#define PHY_TESTCLK            BIT(1)
>> +#define PHY_UNTESTCLK            0
>> +#define PHY_TESTCLR            BIT(0)
>> +#define PHY_UNTESTCLR            0
>> +
>> +#define DSI_PHY_TST_CTRL1        0xb8
>> +#define PHY_TESTEN            BIT(16)
>> +#define PHY_UNTESTEN            0
>> +#define PHY_TESTDOUT(n)            (((n) & 0xff) << 8)
>> +#define PHY_TESTDIN(n)            (((n) & 0xff) << 0)
>> +
>> +#define DSI_INT_ST0            0xbc
>> +#define DSI_INT_ST1            0xc0
>> +#define DSI_INT_MSK0            0xc4
>> +#define DSI_INT_MSK1            0xc8
>> +
>> +#define PHY_STATUS_TIMEOUT_US        10000
>> +#define CMD_PKT_STATUS_TIMEOUT_US    20000
>> +
>> +struct dw_mipi_dsi {
>> +    struct drm_bridge bridge;
>> +    struct mipi_dsi_host dsi_host;
>> +    struct drm_bridge *panel_bridge;
>> +    bool is_panel_bridge;
>> +    struct device *dev;
>> +    void __iomem *base;
>> +
>> +    struct clk *pclk;
>> +
>> +    unsigned int lane_mbps; /* per lane */
>> +    u32 channel;
>> +    u32 lanes;
>> +    u32 format;
>> +    unsigned long mode_flags;
>> +
>> +    const struct dw_mipi_dsi_plat_data *plat_data;
>> +};
>> +
>> +/*
>> + * The controller should generate 2 frames before
>> + * preparing the peripheral.
>> + */
>> +static void dw_mipi_dsi_wait_for_two_frames(struct drm_display_mode 
>> *mode)
>> +{
>> +    int refresh, two_frames;
>> +
>> +    refresh = drm_mode_vrefresh(mode);
>> +    two_frames = DIV_ROUND_UP(MSEC_PER_SEC, refresh) * 2;
>> +    msleep(two_frames);
>> +}
>> +
>> +static inline struct dw_mipi_dsi *host_to_dsi(struct mipi_dsi_host 
>> *host)
>> +{
>> +    return container_of(host, struct dw_mipi_dsi, dsi_host);
>> +}
>> +
>> +static inline struct dw_mipi_dsi *bridge_to_dsi(struct drm_bridge 
>> *bridge)
>> +{
>> +    return container_of(bridge, struct dw_mipi_dsi, bridge);
>> +}
>> +
>> +static inline void dsi_write(struct dw_mipi_dsi *dsi, u32 reg, u32 val)
>> +{
>> +    writel(val, dsi->base + reg);
>> +}
>> +
>> +static inline u32 dsi_read(struct dw_mipi_dsi *dsi, u32 reg)
>> +{
>> +    return readl(dsi->base + reg);
>> +}
>> +
>> +static int dw_mipi_dsi_host_attach(struct mipi_dsi_host *host,
>> +                   struct mipi_dsi_device *device)
>> +{
>> +    struct dw_mipi_dsi *dsi = host_to_dsi(host);
>> +    struct drm_bridge *bridge;
>> +    struct drm_panel *panel;
>> +    int ret;
>> +
>> +    if (device->lanes > dsi->plat_data->max_data_lanes) {
>> +        dev_err(dsi->dev, "the number of data lanes(%u) is too many\n",
>> +            device->lanes);
>> +        return -EINVAL;
>> +    }
>> +
>> +    dsi->lanes = device->lanes;
>> +    dsi->channel = device->channel;
>> +    dsi->format = device->format;
>> +    dsi->mode_flags = device->mode_flags;
>> +
>> +    ret = drm_of_find_panel_or_bridge(host->dev->of_node, 1, 0,
>> +                      &panel, &bridge);
>> +    if (ret)
>> +        return ret;
>> +
>> +    if (panel) {
>> +        bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_DSI);
>> +        if (IS_ERR(bridge))
>> +            return PTR_ERR(bridge);
>> +        dsi->is_panel_bridge = true;
>> +    }
>> +
>> +    dsi->panel_bridge = bridge;
>> +
>> +    return drm_bridge_add(&dsi->bridge);
>> +}
>> +
>> +static int dw_mipi_dsi_host_detach(struct mipi_dsi_host *host,
>> +                   struct mipi_dsi_device *device)
>> +{
>> +    struct dw_mipi_dsi *dsi = host_to_dsi(host);
>> +
>> +    if (dsi->is_panel_bridge)
>> +        drm_panel_bridge_remove(dsi->panel_bridge);
>> +
>> +    drm_bridge_remove(&dsi->bridge);
>> +
>> +    return 0;
>> +}
>> +
>> +static void dw_mipi_message_config(struct dw_mipi_dsi *dsi,
>> +                   const struct mipi_dsi_msg *msg)
>> +{
>> +    bool lpm = msg->flags & MIPI_DSI_MSG_USE_LPM;
>> +    u32 val = 0;
>> +
>> +    if (msg->flags & MIPI_DSI_MSG_REQ_ACK)
>> +        val |= EN_ACK_RQST;
>> +    if (lpm)
>> +        val |= CMD_MODE_ALL_LP;
>> +
>> +    dsi_write(dsi, DSI_LPCLK_CTRL, lpm ? 0 : PHY_TXREQUESTCLKHS);
>> +    dsi_write(dsi, DSI_CMD_MODE_CFG, val);
>> +}
>> +
>> +static int dw_mipi_dsi_gen_pkt_hdr_write(struct dw_mipi_dsi *dsi, u32 
>> hdr_val)
>> +{
>> +    int ret;
>> +    u32 val, mask;
>> +
>> +    ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
>> +                 val, !(val & GEN_CMD_FULL), 1000,
>> +                 CMD_PKT_STATUS_TIMEOUT_US);
>> +    if (ret < 0) {
>> +        dev_err(dsi->dev, "failed to get available command FIFO\n");
>> +        return ret;
>> +    }
>> +
>> +    dsi_write(dsi, DSI_GEN_HDR, hdr_val);
>> +
>> +    mask = GEN_CMD_EMPTY | GEN_PLD_W_EMPTY;
>> +    ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
>> +                 val, (val & mask) == mask,
>> +                 1000, CMD_PKT_STATUS_TIMEOUT_US);
>> +    if (ret < 0) {
>> +        dev_err(dsi->dev, "failed to write command FIFO\n");
>> +        return ret;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +static int dw_mipi_dsi_dcs_short_write(struct dw_mipi_dsi *dsi,
>> +                       const struct mipi_dsi_msg *msg)
>> +{
>> +    const u8 *tx_buf = msg->tx_buf;
>> +    u16 data = 0;
>> +    u32 val;
>> +
>> +    if (msg->tx_len > 0)
>> +        data |= tx_buf[0];
>> +    if (msg->tx_len > 1)
>> +        data |= tx_buf[1] << 8;
>> +
>> +    if (msg->tx_len > 2) {
>> +        dev_err(dsi->dev, "too long tx buf length %zu for short 
>> write\n",
>> +            msg->tx_len);
>> +        return -EINVAL;
>> +    }
>> +
>> +    val = GEN_HDATA(data) | GEN_HTYPE(msg->type);
>> +    return dw_mipi_dsi_gen_pkt_hdr_write(dsi, val);
>> +}
>> +
>> +static int dw_mipi_dsi_dcs_long_write(struct dw_mipi_dsi *dsi,
>> +                      const struct mipi_dsi_msg *msg)
>> +{
>> +    const u8 *tx_buf = msg->tx_buf;
>> +    int len = msg->tx_len, pld_data_bytes = sizeof(u32), ret;
>> +    u32 hdr_val = GEN_HDATA(msg->tx_len) | GEN_HTYPE(msg->type);
>> +    u32 remainder;
>> +    u32 val;
>> +
>> +    if (msg->tx_len < 3) {
>> +        dev_err(dsi->dev, "wrong tx buf length %zu for long write\n",
>> +            msg->tx_len);
>> +        return -EINVAL;
>> +    }
>> +
>> +    while (DIV_ROUND_UP(len, pld_data_bytes)) {
>> +        if (len < pld_data_bytes) {
>> +            remainder = 0;
>> +            memcpy(&remainder, tx_buf, len);
>> +            dsi_write(dsi, DSI_GEN_PLD_DATA, remainder);
>> +            len = 0;
>> +        } else {
>> +            memcpy(&remainder, tx_buf, pld_data_bytes);
>> +            dsi_write(dsi, DSI_GEN_PLD_DATA, remainder);
>> +            tx_buf += pld_data_bytes;
>> +            len -= pld_data_bytes;
>> +        }
>> +
>> +        ret = readl_poll_timeout(dsi->base + DSI_CMD_PKT_STATUS,
>> +                     val, !(val & GEN_PLD_W_FULL), 1000,
>> +                     CMD_PKT_STATUS_TIMEOUT_US);
>> +        if (ret < 0) {
>> +            dev_err(dsi->dev,
>> +                "failed to get available write payload FIFO\n");
>> +            return ret;
>> +        }
>> +    }
>> +
>> +    return dw_mipi_dsi_gen_pkt_hdr_write(dsi, hdr_val);
>> +}
>> +
>> +static ssize_t dw_mipi_dsi_host_transfer(struct mipi_dsi_host *host,
>> +                     const struct mipi_dsi_msg *msg)
>> +{
>> +    struct dw_mipi_dsi *dsi = host_to_dsi(host);
>> +    int ret;
>> +
>> +    /*
>> +     * TODO dw drv improvements
>> +     * use mipi_dsi_create_packet() instead of all following
>> +     * functions and code (no switch cases, no
>> +     * dw_mipi_dsi_dcs_short_write(), only the loop in long_write...)
>> +     * and use packet.header...
>> +     */
>> +    dw_mipi_message_config(dsi, msg);
>> +
>> +    switch (msg->type) {
>> +    case MIPI_DSI_DCS_SHORT_WRITE:
>> +    case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
>> +    case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
>> +        ret = dw_mipi_dsi_dcs_short_write(dsi, msg);
>> +        break;
>> +    case MIPI_DSI_DCS_LONG_WRITE:
>> +        ret = dw_mipi_dsi_dcs_long_write(dsi, msg);
>> +        break;
>> +    default:
>> +        dev_err(dsi->dev, "unsupported message type 0x%02x\n",
>> +            msg->type);
>> +        ret = -EINVAL;
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +static const struct mipi_dsi_host_ops dw_mipi_dsi_host_ops = {
>> +    .attach = dw_mipi_dsi_host_attach,
>> +    .detach = dw_mipi_dsi_host_detach,
>> +    .transfer = dw_mipi_dsi_host_transfer,
>> +};
>> +
>> +static void dw_mipi_dsi_video_mode_config(struct dw_mipi_dsi *dsi)
>> +{
>> +    u32 val;
>> +
>> +    /*
>> +     * TODO dw drv improvements
>> +     * enabling low power is panel-dependent, we should use the
>> +     * panel configuration here...
>> +     */
>> +    val = ENABLE_LOW_POWER;
>> +
>> +    if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST)
>> +        val |= VID_MODE_TYPE_BURST;
>> +    else if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE)
>> +        val |= VID_MODE_TYPE_NON_BURST_SYNC_PULSES;
>> +    else
>> +        val |= VID_MODE_TYPE_NON_BURST_SYNC_EVENTS;
>> +
>> +    dsi_write(dsi, DSI_VID_MODE_CFG, val);
>> +}
>> +
>> +static void dw_mipi_dsi_set_mode(struct dw_mipi_dsi *dsi,
>> +                 unsigned long mode_flags)
>> +{
>> +    dsi_write(dsi, DSI_PWR_UP, RESET);
>> +
>> +    if (mode_flags & MIPI_DSI_MODE_VIDEO) {
>> +        dsi_write(dsi, DSI_MODE_CFG, ENABLE_VIDEO_MODE);
>> +        dw_mipi_dsi_video_mode_config(dsi);
>> +        dsi_write(dsi, DSI_LPCLK_CTRL, PHY_TXREQUESTCLKHS);
>> +    } else {
>> +        dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE);
>> +    }
>> +
>> +    dsi_write(dsi, DSI_PWR_UP, POWERUP);
>> +}
>> +
>> +static void dw_mipi_dsi_disable(struct dw_mipi_dsi *dsi)
>> +{
>> +    dsi_write(dsi, DSI_PWR_UP, RESET);
>> +    dsi_write(dsi, DSI_PHY_RSTZ, PHY_RSTZ);
>> +}
>> +
>> +static void dw_mipi_dsi_init(struct dw_mipi_dsi *dsi)
>> +{
>> +    /*
>> +     * The maximum permitted escape clock is 20MHz and it is derived 
>> from
>> +     * lanebyteclk, which is running at "lane_mbps / 8".  Thus we want:
>> +     *
>> +     *     (lane_mbps >> 3) / esc_clk_division < 20
>> +     * which is:
>> +     *     (lane_mbps >> 3) / 20 > esc_clk_division
>> +     */
>> +    u32 esc_clk_division = (dsi->lane_mbps >> 3) / 20 + 1;
>> +
>> +    dsi_write(dsi, DSI_PWR_UP, RESET);
>> +
>> +    /*
>> +     * TODO dw drv improvements
>> +     * timeout clock division should be computed with the
>> +     * high speed transmission counter timeout and byte lane...
>> +     */
>> +    dsi_write(dsi, DSI_CLKMGR_CFG, TO_CLK_DIVIDSION(10) |
>> +          TX_ESC_CLK_DIVIDSION(esc_clk_division));
>> +}
>> +
>> +static void dw_mipi_dsi_dpi_config(struct dw_mipi_dsi *dsi,
>> +                   struct drm_display_mode *mode)
>> +{
>> +    u32 val = 0, color = 0;
>> +
>> +    switch (dsi->format) {
>> +    case MIPI_DSI_FMT_RGB888:
>> +        color = DPI_COLOR_CODING_24BIT;
>> +        break;
>> +    case MIPI_DSI_FMT_RGB666:
>> +        color = DPI_COLOR_CODING_18BIT_2 | EN18_LOOSELY;
>> +        break;
>> +    case MIPI_DSI_FMT_RGB666_PACKED:
>> +        color = DPI_COLOR_CODING_18BIT_1;
>> +        break;
>> +    case MIPI_DSI_FMT_RGB565:
>> +        color = DPI_COLOR_CODING_16BIT_1;
>> +        break;
>> +    }
>> +
>> +    if (mode->flags & DRM_MODE_FLAG_NVSYNC)
>> +        val |= VSYNC_ACTIVE_LOW;
>> +    if (mode->flags & DRM_MODE_FLAG_NHSYNC)
>> +        val |= HSYNC_ACTIVE_LOW;
>> +
>> +    dsi_write(dsi, DSI_DPI_VCID, DPI_VID(dsi->channel));
>> +    dsi_write(dsi, DSI_DPI_COLOR_CODING, color);
>> +    dsi_write(dsi, DSI_DPI_CFG_POL, val);
>> +    /*
>> +     * TODO dw drv improvements
>> +     * largest packet sizes during hfp or during vsa/vpb/vfp
>> +     * should be computed according to byte lane, lane number and only
>> +     * if sending lp cmds in high speed is enable (PHY_TXREQUESTCLKHS)
>> +     */
>> +    dsi_write(dsi, DSI_DPI_LP_CMD_TIM, OUTVACT_LPCMD_TIME(4)
>> +          | INVACT_LPCMD_TIME(4));
>> +}
>> +
>> +static void dw_mipi_dsi_packet_handler_config(struct dw_mipi_dsi *dsi)
>> +{
>> +    dsi_write(dsi, DSI_PCKHDL_CFG, EN_CRC_RX | EN_ECC_RX | EN_BTA);
>> +}
>> +
>> +static void dw_mipi_dsi_video_packet_config(struct dw_mipi_dsi *dsi,
>> +                        struct drm_display_mode *mode)
>> +{
>> +    /*
>> +     * TODO dw drv improvements
>> +     * only burst mode is supported here. For non-burst video modes,
>> +     * we should compute DSI_VID_PKT_SIZE, DSI_VCCR.NUMC &
>> +     * DSI_VNPCR.NPSIZE... especially because this driver supports
>> +     * non-burst video modes, see dw_mipi_dsi_video_mode_config()...
>> +     */
>> +    dsi_write(dsi, DSI_VID_PKT_SIZE, VID_PKT_SIZE(mode->hdisplay));
>> +}
>> +
>> +static void dw_mipi_dsi_command_mode_config(struct dw_mipi_dsi *dsi)
>> +{
>> +    /*
>> +     * TODO dw drv improvements
>> +     * compute high speed transmission counter timeout according
>> +     * to the timeout clock division (TO_CLK_DIVIDSION) and byte lane...
>> +     */
>> +    dsi_write(dsi, DSI_TO_CNT_CFG, HSTX_TO_CNT(1000) | 
>> LPRX_TO_CNT(1000));
>> +    /*
>> +     * TODO dw drv improvements
>> +     * the Bus-Turn-Around Timeout Counter should be computed
>> +     * according to byte lane...
>> +     */
>> +    dsi_write(dsi, DSI_BTA_TO_CNT, 0xd00);
>> +    dsi_write(dsi, DSI_MODE_CFG, ENABLE_CMD_MODE);
>> +}
>> +
>> +/* Get lane byte clock cycles. */
>> +static u32 dw_mipi_dsi_get_hcomponent_lbcc(struct dw_mipi_dsi *dsi,
>> +                       struct drm_display_mode *mode,
>> +                       u32 hcomponent)
>> +{
>> +    u32 frac, lbcc;
>> +
>> +    lbcc = hcomponent * dsi->lane_mbps * MSEC_PER_SEC / 8;
>> +
>> +    frac = lbcc % mode->clock;
>> +    lbcc = lbcc / mode->clock;
>> +    if (frac)
>> +        lbcc++;
>> +
>> +    return lbcc;
>> +}
>> +
>> +static void dw_mipi_dsi_line_timer_config(struct dw_mipi_dsi *dsi,
>> +                      struct drm_display_mode *mode)
>> +{
>> +    u32 htotal, hsa, hbp, lbcc;
>> +
>> +    htotal = mode->htotal;
>> +    hsa = mode->hsync_end - mode->hsync_start;
>> +    hbp = mode->htotal - mode->hsync_end;
>> +
>> +    /*
>> +     * TODO dw drv improvements
>> +     * computations below may be improved...
>> +     */
>> +    lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, htotal);
>> +    dsi_write(dsi, DSI_VID_HLINE_TIME, lbcc);
>> +
>> +    lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, hsa);
>> +    dsi_write(dsi, DSI_VID_HSA_TIME, lbcc);
>> +
>> +    lbcc = dw_mipi_dsi_get_hcomponent_lbcc(dsi, mode, hbp);
>> +    dsi_write(dsi, DSI_VID_HBP_TIME, lbcc);
>> +}
>> +
>> +static void dw_mipi_dsi_vertical_timing_config(struct dw_mipi_dsi *dsi,
>> +                           struct drm_display_mode *mode)
>> +{
>> +    u32 vactive, vsa, vfp, vbp;
>> +
>> +    vactive = mode->vdisplay;
>> +    vsa = mode->vsync_end - mode->vsync_start;
>> +    vfp = mode->vsync_start - mode->vdisplay;
>> +    vbp = mode->vtotal - mode->vsync_end;
>> +
>> +    dsi_write(dsi, DSI_VID_VACTIVE_LINES, vactive);
>> +    dsi_write(dsi, DSI_VID_VSA_LINES, vsa);
>> +    dsi_write(dsi, DSI_VID_VFP_LINES, vfp);
>> +    dsi_write(dsi, DSI_VID_VBP_LINES, vbp);
>> +}
>> +
>> +static void dw_mipi_dsi_dphy_timing_config(struct dw_mipi_dsi *dsi)
>> +{
>> +    /*
>> +     * TODO dw drv improvements
>> +     * data & clock lane timers should be computed according to panel
>> +     * blankings and to the automatic clock lane control mode...
>> +     * note: DSI_PHY_TMR_CFG.MAX_RD_TIME should be in line with
>> +     * DSI_CMD_MODE_CFG.MAX_RD_PKT_SIZE_LP (see CMD_MODE_ALL_LP)
>> +     */
>> +    dsi_write(dsi, DSI_PHY_TMR_CFG, PHY_HS2LP_TIME(0x40)
>> +          | PHY_LP2HS_TIME(0x40) | MAX_RD_TIME(10000));
>> +
>> +    dsi_write(dsi, DSI_PHY_TMR_LPCLK_CFG, PHY_CLKHS2LP_TIME(0x40)
>> +          | PHY_CLKLP2HS_TIME(0x40));
>> +}
>> +
>> +static void dw_mipi_dsi_dphy_interface_config(struct dw_mipi_dsi *dsi)
>> +{
>> +    /*
>> +     * TODO dw drv improvements
>> +     * stop wait time should be the maximum between host dsi
>> +     * and panel stop wait times
>> +     */
>> +    dsi_write(dsi, DSI_PHY_IF_CFG, PHY_STOP_WAIT_TIME(0x20) |
>> +          N_LANES(dsi->lanes));
>> +}
>> +
>> +static void dw_mipi_dsi_dphy_init(struct dw_mipi_dsi *dsi)
>> +{
>> +    /* Clear PHY state */
>> +    dsi_write(dsi, DSI_PHY_RSTZ, PHY_DISFORCEPLL | PHY_DISABLECLK
>> +          | PHY_RSTZ | PHY_SHUTDOWNZ);
>> +    dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLR);
>> +    dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_TESTCLR);
>> +    dsi_write(dsi, DSI_PHY_TST_CTRL0, PHY_UNTESTCLR);
>> +}
>> +
>> +static void dw_mipi_dsi_dphy_enable(struct dw_mipi_dsi *dsi)
>> +{
>> +    u32 val;
>> +    int ret;
>> +
>> +    dsi_write(dsi, DSI_PHY_RSTZ, PHY_ENFORCEPLL | PHY_ENABLECLK |
>> +          PHY_UNRSTZ | PHY_UNSHUTDOWNZ);
>> +
>> +    ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS,
>> +                 val, val & LOCK, 1000, PHY_STATUS_TIMEOUT_US);
>> +    if (ret < 0)
>> +        DRM_DEBUG_DRIVER("failed to wait phy lock state\n");
>> +
>> +    ret = readl_poll_timeout(dsi->base + DSI_PHY_STATUS,
>> +                 val, val & STOP_STATE_CLK_LANE, 1000,
>> +                 PHY_STATUS_TIMEOUT_US);
>> +    if (ret < 0)
>> +        DRM_DEBUG_DRIVER("failed to wait phy clk lane stop state\n");
>> +}
>> +
>> +static void dw_mipi_dsi_clear_err(struct dw_mipi_dsi *dsi)
>> +{
>> +    dsi_read(dsi, DSI_INT_ST0);
>> +    dsi_read(dsi, DSI_INT_ST1);
>> +    dsi_write(dsi, DSI_INT_MSK0, 0);
>> +    dsi_write(dsi, DSI_INT_MSK1, 0);
>> +}
>> +
>> +static void dw_mipi_dsi_bridge_post_disable(struct drm_bridge *bridge)
>> +{
>> +    struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
>> +
>> +    /*
>> +     * Switch to cmd mode before panel-bridge disable & panel unprepare.
>> +     * Note: panel-bridge disable & panel disable has been called
>> +     * before by the drm framework.
> 
> I don't think that's exactly the case. I think the sequence should be as 
> in the
> call chain below.
> 

Hi Archit,
And many thanks for your comments :-)
the word "post_" is missing in the above comment, sorry for that. I 
should have written "Switch to cmd mode before panel-bridge post_disable 
& ..." that is much more correct I think, I will update this comment for 
v5 : )


>> +     */
>> +    dw_mipi_dsi_set_mode(dsi, 0);
>> +
>> +    /*
>> +     * TODO Only way found to call panel-bridge disable & panel 
>> unprepare
>> +     * before the dsi "final" disable... can we do better?
> 
> I agree, this is a problem. More below.

Same remark here, I forgot "post_" in the above comment.

> 
>> +     */
>> +    drm_bridge_post_disable(dsi->panel_bridge);
>> +
> 
> I'm guessing our display chain is something like:
> 
> KMS_encoder -> DW_DSI_bridge -> Panel_bridge -> Panel
> 
> The order in which the disable ops are called:
> 
> drm_bridge_disable(Panel_bridge)
>    - drm_panel_disable(Panel)
> drm_bridge_disable(DW_DSI_bridge)
> encoder_funcs->prepare(KMS_encoder)
> drm_bridge_post_disable(DW_DSI_bridge)
> drm_bridge_post_disable(Panel_bridge)
>    - drm_panel_unprepare(Panel)
> 

100%-perfect sequence, I do agree with you : )

> Assuming that only drm_panel_unprepare() requires sending DSI commands, 

Well, it really depends on DSI panels. For instance, panel drivers can 
send DCS/Generic DSI commands:
* in drm_panel_disable(): then these commands are sent during blankings, 
many lcds allow that. This is the proper place for backlight through DSI 
(dimming or off), for sleep mode DCS commands...

or/and

* in drm_panel_unprepare(): then these commands are sent during a 
"command mode" phase. This is the proper place for many things, from 
backlight off through DSI, sleep mode DCS commands... to a full power 
off (voltage regulators are switched off).

 From my pov, both drm_panel_disable() & drm_panel_unprepare() may send 
DSI commands... but it is not a real problem in fact as DSI commands can 
be sent through blankings in video mode or can be sent in "command mode"...

> you could have
> switched to command mode in DW_DSI_bridge's disable() op, and do the 
> "final" DSI disable
> in DW_DSI_bridge's post_disable(), but that would still result in 
> drm_panel_unprepare()
> being called with the DSI host dead.
> 
> The existing call chain of consecutive bridges is the most symmetric 
> one, and the one
> expected to work in most cases, but it clearly doesn't work in your use 
> case.
> 
> We have a few options:
> 
> - Undo the drm-panel-bridge stuff, and have the freedom of calling 
> drm_panel ops in
> whatever order we want.
> 
> - Put a big TODO/HACK comment here, saying that this needs to be fixed 
> in the drm_bridge
> framework and the API needs to be updated to manage our own call chains. 
> Also,
> instead of calling "drm_bridge_post_disable(dsi->panel_bridge);" 
> explicitly, we
> can manually call panel_bridge->post_disable() op directly. This avoids 
> us doing
> things recursively.
> 
> We would implement the TODO task in drm_bridges only when there are more 
> people
> desperately in the need to have customizable call chains of bridge ops 
> for long
> display chains, so I don't see it being implemented in the near future, 
> but I don't
> think there should be any problem keeping this hack in the dw dsi driver 
> for now.
> 
> What choice do you prefer?

Well, not so easy to decide what could be the best solution...

For the time being, I think I prefer keeping the panel bridge proposal 
(the v4 one), for several reasons in fact:

* It saves "many" lines of code, and supporting *both* panels & bridges 
(homogeneous approach).

* It helps reducing explicit calls like drm_panel_() or drm_bridge_() 
letting the drm framework doing its job :-)

* It is not an issue to have a TODO/HACK for the only remaining function 
call (drm_bridge_post_disable() here). I mean many others drivers calls 
directly these panel & bridge functions and this forces panel drivers to 
have in many places in their code "if (enabled) return;" or "if 
(prepared) return;" and we should work in the future to improve that 
(ie. Let's drm framework doing its job).

* It covers/offers the 3 important "hw disable" phases:
	- panel sends DCS/Generic DSI commands during its blankings in a video 
mode phase (most of the times, these commands are short, for backlight 
updates or sleep for instance...), it's correspond to panel_disable().
	- panel sends DCS/Generic DSI commands in a command mode phase (sleep, 
power off...), it's correspond to panel_unprepare().
	- the dsi IP is stopped after the 2 previous phases.

So, for all these reasons, I prefer the "Put a big TODO/HACK" option :)

Thank you,
Philippe

> 
> Eric, Daniel,
> 
> Fyi, this is another case where the panel-bridge stuff doesn't work so 
> well. Not
> criticizing or anything, just pointing out :)
> 
> Archit
> 
> 
>> +    dw_mipi_dsi_disable(dsi);
>> +    clk_disable_unprepare(dsi->pclk);
>> +    pm_runtime_put(dsi->dev);
>> +}
>> +
>> +void dw_mipi_dsi_bridge_mode_set(struct drm_bridge *bridge,
>> +                 struct drm_display_mode *mode,
>> +                 struct drm_display_mode *adjusted_mode)
>> +{
>> +    struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
>> +    const struct dw_mipi_dsi_phy_ops *phy_ops = dsi->plat_data->phy_ops;
>> +    void *priv_data = dsi->plat_data->priv_data;
>> +    int ret;
>> +
>> +    clk_prepare_enable(dsi->pclk);
>> +
>> +    ret = phy_ops->get_lane_mbps(priv_data, mode, dsi->mode_flags,
>> +                     dsi->lanes, dsi->format, &dsi->lane_mbps);
>> +    if (ret)
>> +        DRM_DEBUG_DRIVER("Phy get_lane_mbps() failed\n");
>> +
>> +    pm_runtime_get_sync(dsi->dev);
>> +    dw_mipi_dsi_init(dsi);
>> +    dw_mipi_dsi_dpi_config(dsi, mode);
>> +    dw_mipi_dsi_packet_handler_config(dsi);
>> +    dw_mipi_dsi_video_mode_config(dsi);
>> +    dw_mipi_dsi_video_packet_config(dsi, mode);
>> +    dw_mipi_dsi_command_mode_config(dsi);
>> +    dw_mipi_dsi_line_timer_config(dsi, mode);
>> +    dw_mipi_dsi_vertical_timing_config(dsi, mode);
>> +
>> +    dw_mipi_dsi_dphy_init(dsi);
>> +    dw_mipi_dsi_dphy_timing_config(dsi);
>> +    dw_mipi_dsi_dphy_interface_config(dsi);
>> +
>> +    dw_mipi_dsi_clear_err(dsi);
>> +
>> +    ret = phy_ops->init(priv_data);
>> +    if (ret)
>> +        DRM_DEBUG_DRIVER("Phy init() failed\n");
>> +
>> +    dw_mipi_dsi_dphy_enable(dsi);
>> +
>> +    dw_mipi_dsi_wait_for_two_frames(mode);
>> +
>> +    /* Switch to cmd mode for panel-bridge pre_enable & panel prepare */
>> +    dw_mipi_dsi_set_mode(dsi, 0);
>> +}
>> +
>> +static void dw_mipi_dsi_bridge_enable(struct drm_bridge *bridge)
>> +{
>> +    struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
>> +
>> +    /* Switch to video mode for panel-bridge enable & panel enable */
>> +    dw_mipi_dsi_set_mode(dsi, MIPI_DSI_MODE_VIDEO);
>> +}
>> +
>> +static enum drm_mode_status
>> +dw_mipi_dsi_bridge_mode_valid(struct drm_bridge *bridge,
>> +                  const struct drm_display_mode *mode)
>> +{
>> +    struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
>> +    const struct dw_mipi_dsi_plat_data *pdata = dsi->plat_data;
>> +    enum drm_mode_status mode_status = MODE_OK;
>> +
>> +    if (pdata->mode_valid)
>> +        mode_status = pdata->mode_valid(pdata->priv_data, mode);
>> +
>> +    return mode_status;
>> +}
>> +
>> +static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge)
>> +{
>> +    struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
>> +
>> +    if (!bridge->encoder) {
>> +        DRM_ERROR("Parent encoder object not found\n");
>> +        return -ENODEV;
>> +    }
>> +
>> +    /* Set the encoder type as caller does not know it */
>> +    bridge->encoder->encoder_type = DRM_MODE_ENCODER_DSI;
>> +
>> +    /* Attach the panel-bridge to the dsi bridge */
>> +    return drm_bridge_attach(bridge->encoder, dsi->panel_bridge, 
>> bridge);
>> +}
>> +
>> +static struct drm_bridge_funcs dw_mipi_dsi_bridge_funcs = {
>> +    .mode_set     = dw_mipi_dsi_bridge_mode_set,
>> +    .enable          = dw_mipi_dsi_bridge_enable,
>> +    .post_disable = dw_mipi_dsi_bridge_post_disable,
>> +    .mode_valid   = dw_mipi_dsi_bridge_mode_valid,
>> +    .attach          = dw_mipi_dsi_bridge_attach,
>> +};
>> +
>> +static struct dw_mipi_dsi *
>> +__dw_mipi_dsi_probe(struct platform_device *pdev,
>> +            const struct dw_mipi_dsi_plat_data *plat_data)
>> +{
>> +    struct device *dev = &pdev->dev;
>> +    struct reset_control *apb_rst;
>> +    struct dw_mipi_dsi *dsi;
>> +    struct resource *res;
>> +    int ret;
>> +
>> +    dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
>> +    if (!dsi)
>> +        return ERR_PTR(-ENOMEM);
>> +
>> +    dsi->dev = dev;
>> +    dsi->plat_data = plat_data;
>> +
>> +    if (!plat_data->phy_ops->init || 
>> !plat_data->phy_ops->get_lane_mbps) {
>> +        DRM_ERROR("Phy not properly configured\n");
>> +        return ERR_PTR(-ENODEV);
>> +    }
>> +
>> +    if (!plat_data->base) {
>> +        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +        if (!res)
>> +            return ERR_PTR(-ENODEV);
>> +
>> +        dsi->base = devm_ioremap_resource(dev, res);
>> +        if (IS_ERR(dsi->base))
>> +            return ERR_PTR(-ENODEV);
>> +
>> +    } else {
>> +        dsi->base = plat_data->base;
>> +    }
>> +
>> +    dsi->pclk = devm_clk_get(dev, "pclk");
>> +    if (IS_ERR(dsi->pclk)) {
>> +        ret = PTR_ERR(dsi->pclk);
>> +        dev_err(dev, "Unable to get pclk: %d\n", ret);
>> +        return ERR_PTR(ret);
>> +    }
>> +
>> +    /*
>> +     * Note that the reset was not defined in the initial device 
>> tree, so
>> +     * we have to be prepared for it not being found.
>> +     */
>> +    apb_rst = devm_reset_control_get(dev, "apb");
>> +    if (IS_ERR(apb_rst)) {
>> +        ret = PTR_ERR(apb_rst);
>> +        if (ret == -ENOENT) {
>> +            apb_rst = NULL;
>> +        } else {
>> +            dev_err(dev, "Unable to get reset control: %d\n", ret);
>> +            return ERR_PTR(ret);
>> +        }
>> +    }
>> +
>> +    if (apb_rst) {
>> +        ret = clk_prepare_enable(dsi->pclk);
>> +        if (ret) {
>> +            dev_err(dev, "%s: Failed to enable pclk\n", __func__);
>> +            return ERR_PTR(ret);
>> +        }
>> +
>> +        reset_control_assert(apb_rst);
>> +        usleep_range(10, 20);
>> +        reset_control_deassert(apb_rst);
>> +
>> +        clk_disable_unprepare(dsi->pclk);
>> +    }
>> +
>> +    pm_runtime_enable(dev);
>> +
>> +    dsi->dsi_host.ops = &dw_mipi_dsi_host_ops;
>> +    dsi->dsi_host.dev = dev;
>> +    ret = mipi_dsi_host_register(&dsi->dsi_host);
>> +    if (ret) {
>> +        dev_err(dev, "Failed to register MIPI host: %d\n", ret);
>> +        return ERR_PTR(ret);
>> +    }
>> +
>> +    dsi->bridge.driver_private = dsi;
>> +    dsi->bridge.funcs = &dw_mipi_dsi_bridge_funcs;
>> +#ifdef CONFIG_OF
>> +    dsi->bridge.of_node = pdev->dev.of_node;
>> +#endif
>> +
>> +    dev_set_drvdata(dev, dsi);
>> +
>> +    return dsi;
>> +}
>> +
>> +static void __dw_mipi_dsi_remove(struct dw_mipi_dsi *dsi)
>> +{
>> +    pm_runtime_disable(dsi->dev);
>> +}
>> +
>> +/*
>> + * Probe/remove API, used from platforms based on the DRM bridge API.
>> + */
>> +int dw_mipi_dsi_probe(struct platform_device *pdev,
>> +              const struct dw_mipi_dsi_plat_data *plat_data)
>> +{
>> +    struct dw_mipi_dsi *dsi;
>> +
>> +    dsi = __dw_mipi_dsi_probe(pdev, plat_data);
>> +    if (IS_ERR(dsi))
>> +        return PTR_ERR(dsi);
>> +
>> +    return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(dw_mipi_dsi_probe);
>> +
>> +void dw_mipi_dsi_remove(struct platform_device *pdev)
>> +{
>> +    struct dw_mipi_dsi *dsi = platform_get_drvdata(pdev);
>> +
>> +    mipi_dsi_host_unregister(&dsi->dsi_host);
>> +
>> +    __dw_mipi_dsi_remove(dsi);
>> +}
>> +EXPORT_SYMBOL_GPL(dw_mipi_dsi_remove);
>> +
>> +/*
>> + * Bind/unbind API, used from platforms based on the component 
>> framework.
>> + */
>> +int dw_mipi_dsi_bind(struct platform_device *pdev, struct drm_encoder 
>> *encoder,
>> +             const struct dw_mipi_dsi_plat_data *plat_data)
>> +{
>> +    struct dw_mipi_dsi *dsi;
>> +    int ret;
>> +
>> +    dsi = __dw_mipi_dsi_probe(pdev, plat_data);
>> +    if (IS_ERR(dsi))
>> +        return PTR_ERR(dsi);
>> +
>> +    ret = drm_bridge_attach(encoder, &dsi->bridge, NULL);
>> +    if (ret) {
>> +        dw_mipi_dsi_remove(pdev);
>> +        DRM_ERROR("Failed to initialize bridge with drm\n");
>> +        return ret;
>> +    }
>> +
>> +    return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(dw_mipi_dsi_bind);
>> +
>> +void dw_mipi_dsi_unbind(struct device *dev)
>> +{
>> +    struct dw_mipi_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +    __dw_mipi_dsi_remove(dsi);
>> +}
>> +EXPORT_SYMBOL_GPL(dw_mipi_dsi_unbind);
>> +
>> +MODULE_AUTHOR("Chris Zhong <zyw@rock-chips.com>");
>> +MODULE_AUTHOR("Philippe Cornu <philippe.cornu@st.com>");
>> +MODULE_DESCRIPTION("DW MIPI DSI host controller driver");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:dw-mipi-dsi");
>> diff --git a/include/drm/bridge/dw_mipi_dsi.h 
>> b/include/drm/bridge/dw_mipi_dsi.h
>> new file mode 100644
>> index 0000000..9b30fec
>> --- /dev/null
>> +++ b/include/drm/bridge/dw_mipi_dsi.h
>> @@ -0,0 +1,39 @@
>> +/*
>> + * Copyright (C) STMicroelectronics SA 2017
>> + *
>> + * Authors: Philippe Cornu <philippe.cornu@st.com>
>> + *          Yannick Fertre <yannick.fertre@st.com>
>> + *
>> + * License terms:  GNU General Public License (GPL), version 2
>> + */
>> +
>> +#ifndef __DW_MIPI_DSI__
>> +#define __DW_MIPI_DSI__
>> +
>> +struct dw_mipi_dsi_phy_ops {
>> +    int (*init)(void *priv_data);
>> +    int (*get_lane_mbps)(void *priv_data, struct drm_display_mode *mode,
>> +                 unsigned long mode_flags, u32 lanes, u32 format,
>> +                 unsigned int *lane_mbps);
>> +};
>> +
>> +struct dw_mipi_dsi_plat_data {
>> +    void __iomem *base;
>> +    unsigned int max_data_lanes;
>> +
>> +    enum drm_mode_status (*mode_valid)(void *priv_data,
>> +                       const struct drm_display_mode *mode);
>> +
>> +    const struct dw_mipi_dsi_phy_ops *phy_ops;
>> +
>> +    void *priv_data;
>> +};
>> +
>> +int dw_mipi_dsi_probe(struct platform_device *pdev,
>> +              const struct dw_mipi_dsi_plat_data *plat_data);
>> +void dw_mipi_dsi_remove(struct platform_device *pdev);
>> +int dw_mipi_dsi_bind(struct platform_device *pdev, struct drm_encoder 
>> *encoder,
>> +             const struct dw_mipi_dsi_plat_data *plat_data);
>> +void dw_mipi_dsi_unbind(struct device *dev);
>> +
>> +#endif /* __DW_MIPI_DSI__ */
>>
>