On Thu, Jun 15, 2017 at 01:29:33AM +1000, Jonathan Liu wrote:
> The documentation for drm_do_get_edid in drivers/gpu/drm/drm_edid.c states:
> "As in the general case the DDC bus is accessible by the kernel at the I2C
> level, drivers must make all reasonable efforts to expose it as an I2C
> adapter and use drm_get_edid() instead of abusing this function."
> 
> Exposing the DDC bus as an I2C adapter is more beneficial as it can be used
> for purposes other than reading the EDID such as modifying the EDID or
> using the HDMI DDC pins as an I2C bus through the I2C dev interface from
> userspace (e.g. i2c-tools).
> 
> Implement this for A10s.
> 
> Signed-off-by: Jonathan Liu <net...@gmail.com>
> ---
> Changes for v3:
>  - Explain why drm_do_get_edid should be used and why it's better to expose it
>    as an I2C adapter in commit message
>  - Reorder bit defines in descending order for consistency
>  - Keep old unused macros instead of removing them
>  - The v2 algorithm split large transfers into 16 byte transfers but this may
>    cause a large single write to be treated as multiple writes causing data
>    corruption. The algorithm has been reworked to not split larger transfers
>    and make more use of the FIFO to avoid this.
>  - Moved the creation of the DDC clock from sun4i_hdmi_enc.c to
>    sun4i_hdmi_i2c.c
>  - Reformatted code
>  - Instead of masking bits that we don't want to check for errors, explicitly
>    check the error bits
>  - Clear error bits at start of transfer in case of error from previous 
> transfer
>  - Poll for completion of FIFO clear after setting FIFO clear bit
> 
> Changes for v2:
>  - Rebased against Maxime's sunxi-drm/for-next branch
>  - Fix up error paths in sun4i_hdmi_bind so that the I2C adapter is deleted if
>    any of the calls after the I2C adapter is created fails
>  - Remove unnecessary includes in sun4i_hdmi_i2c.c
> 
>  drivers/gpu/drm/sun4i/Makefile         |   1 +
>  drivers/gpu/drm/sun4i/sun4i_hdmi.h     |  21 ++++
>  drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 101 ++-------------
>  drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c | 220 
> +++++++++++++++++++++++++++++++++
>  4 files changed, 253 insertions(+), 90 deletions(-)
>  create mode 100644 drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
> 
> diff --git a/drivers/gpu/drm/sun4i/Makefile b/drivers/gpu/drm/sun4i/Makefile
> index e29fd3a2ba9c..43c753cafc88 100644
> --- a/drivers/gpu/drm/sun4i/Makefile
> +++ b/drivers/gpu/drm/sun4i/Makefile
> @@ -2,6 +2,7 @@ sun4i-drm-y += sun4i_drv.o
>  sun4i-drm-y += sun4i_framebuffer.o
>  
>  sun4i-drm-hdmi-y += sun4i_hdmi_enc.o
> +sun4i-drm-hdmi-y += sun4i_hdmi_i2c.o
>  sun4i-drm-hdmi-y += sun4i_hdmi_ddc_clk.o
>  sun4i-drm-hdmi-y += sun4i_hdmi_tmds_clk.o
>  
> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h 
> b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> index 2f2f2ff1ea63..018af9cbb593 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
> @@ -96,6 +96,7 @@
>  #define SUN4I_HDMI_DDC_CTRL_ENABLE           BIT(31)
>  #define SUN4I_HDMI_DDC_CTRL_START_CMD                BIT(30)
>  #define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK    BIT(8)
> +#define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE   (1 << 8)
>  #define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ    (0 << 8)
>  #define SUN4I_HDMI_DDC_CTRL_RESET            BIT(0)
>  
> @@ -105,14 +106,30 @@
>  #define SUN4I_HDMI_DDC_ADDR_OFFSET(off)              (((off) & 0xff) << 8)
>  #define SUN4I_HDMI_DDC_ADDR_SLAVE(addr)              ((addr) & 0xff)
>  
> +#define SUN4I_HDMI_DDC_INT_STATUS_REG        0x50c
> +#define SUN4I_HDMI_DDC_INT_STATUS_ILLEGAL_FIFO_OPERATION     BIT(7)
> +#define SUN4I_HDMI_DDC_INT_STATUS_DDC_RX_FIFO_UNDERFLOW      BIT(6)
> +#define SUN4I_HDMI_DDC_INT_STATUS_DDC_TX_FIFO_UNDERFLOW      BIT(5)
> +#define SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST       BIT(4)
> +#define SUN4I_HDMI_DDC_INT_STATUS_ARBITRATION_ERROR  BIT(3)
> +#define SUN4I_HDMI_DDC_INT_STATUS_ACK_ERROR  BIT(2)
> +#define SUN4I_HDMI_DDC_INT_STATUS_BUS_ERROR  BIT(1)
> +#define SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE  BIT(0)
> +
>  #define SUN4I_HDMI_DDC_FIFO_CTRL_REG 0x510
>  #define SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR               BIT(31)
>  
> +#define SUN4I_HDMI_DDC_FIFO_STATUS_REG       0x514
> +#define SUN4I_HDMI_DDC_FIFO_STATUS_FULL      BIT(6)
> +#define SUN4I_HDMI_DDC_FIFO_STATUS_EMPTY     BIT(5)
> +

The indentation of those bits and the ones above are weird, please
check them.

>  #define SUN4I_HDMI_DDC_FIFO_DATA_REG 0x518
>  #define SUN4I_HDMI_DDC_BYTE_COUNT_REG        0x51c
>  
>  #define SUN4I_HDMI_DDC_CMD_REG               0x520
>  #define SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ        6
> +#define SUN4I_HDMI_DDC_CMD_IMPLICIT_READ     5
> +#define SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE    3
>  
>  #define SUN4I_HDMI_DDC_CLK_REG               0x528
>  #define SUN4I_HDMI_DDC_CLK_M(m)                      (((m) & 0x7) << 3)
> @@ -123,6 +140,7 @@
>  #define SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE  BIT(8)
>  
>  #define SUN4I_HDMI_DDC_FIFO_SIZE     16
> +#define SUN4I_HDMI_DDC_MAX_TRANSFER_SIZE   1023

Where is that limit mentionned ?

>  
>  enum sun4i_hdmi_pkt_type {
>       SUN4I_HDMI_PKT_AVI = 2,
> @@ -146,6 +164,8 @@ struct sun4i_hdmi {
>       struct clk              *ddc_clk;
>       struct clk              *tmds_clk;
>  
> +     struct i2c_adapter      *i2c;
> +
>       struct sun4i_drv        *drv;
>  
>       bool                    hdmi_monitor;
> @@ -153,5 +173,6 @@ struct sun4i_hdmi {
>  
>  int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *clk);
>  int sun4i_tmds_create(struct sun4i_hdmi *hdmi);
> +int sun4i_hdmi_i2c_create(struct sun4i_hdmi *hdmi);
>  
>  #endif /* _SUN4I_HDMI_H_ */
> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c 
> b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> index d3398f6250ef..57a9a7a13e02 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
> @@ -29,8 +29,6 @@
>  #include "sun4i_hdmi.h"
>  #include "sun4i_tcon.h"
>  
> -#define DDC_SEGMENT_ADDR     0x30
> -
>  static inline struct sun4i_hdmi *
>  drm_encoder_to_sun4i_hdmi(struct drm_encoder *encoder)
>  {
> @@ -184,93 +182,13 @@ static const struct drm_encoder_funcs sun4i_hdmi_funcs 
> = {
>       .destroy        = drm_encoder_cleanup,
>  };
>  
> -static int sun4i_hdmi_read_sub_block(struct sun4i_hdmi *hdmi,
> -                                  unsigned int blk, unsigned int offset,
> -                                  u8 *buf, unsigned int count)
> -{
> -     unsigned long reg;
> -     int i;
> -
> -     reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> -     reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
> -     writel(reg | SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ,
> -            hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> -
> -     writel(SUN4I_HDMI_DDC_ADDR_SEGMENT(offset >> 8) |
> -            SUN4I_HDMI_DDC_ADDR_EDDC(DDC_SEGMENT_ADDR << 1) |
> -            SUN4I_HDMI_DDC_ADDR_OFFSET(offset) |
> -            SUN4I_HDMI_DDC_ADDR_SLAVE(DDC_ADDR),
> -            hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
> -
> -     reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
> -     writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
> -            hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
> -
> -     writel(count, hdmi->base + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
> -     writel(SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ,
> -            hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
> -
> -     reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> -     writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
> -            hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> -
> -     if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
> -                            !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
> -                            100, 100000))
> -             return -EIO;
> -
> -     for (i = 0; i < count; i++)
> -             buf[i] = readb(hdmi->base + SUN4I_HDMI_DDC_FIFO_DATA_REG);
> -
> -     return 0;
> -}
> -
> -static int sun4i_hdmi_read_edid_block(void *data, u8 *buf, unsigned int blk,
> -                                   size_t length)
> -{
> -     struct sun4i_hdmi *hdmi = data;
> -     int retry = 2, i;
> -
> -     do {
> -             for (i = 0; i < length; i += SUN4I_HDMI_DDC_FIFO_SIZE) {
> -                     unsigned char offset = blk * EDID_LENGTH + i;
> -                     unsigned int count = min((unsigned 
> int)SUN4I_HDMI_DDC_FIFO_SIZE,
> -                                              length - i);
> -                     int ret;
> -
> -                     ret = sun4i_hdmi_read_sub_block(hdmi, blk, offset,
> -                                                     buf + i, count);
> -                     if (ret)
> -                             return ret;
> -             }
> -     } while (!drm_edid_block_valid(buf, blk, true, NULL) && (retry--));
> -
> -     return 0;
> -}
> -
>  static int sun4i_hdmi_get_modes(struct drm_connector *connector)
>  {
>       struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
> -     unsigned long reg;
>       struct edid *edid;
>       int ret;
>  
> -     /* Reset i2c controller */
> -     writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
> -            hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> -     if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
> -                            !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
> -                            100, 2000))
> -             return -EIO;
> -
> -     writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
> -            SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
> -            hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
> -
> -     clk_prepare_enable(hdmi->ddc_clk);
> -     clk_set_rate(hdmi->ddc_clk, 100000);
> -
> -     edid = drm_do_get_edid(connector, sun4i_hdmi_read_edid_block, hdmi);
> +     edid = drm_get_edid(connector, hdmi->i2c);
>       if (!edid)
>               return 0;
>  
> @@ -282,8 +200,6 @@ static int sun4i_hdmi_get_modes(struct drm_connector 
> *connector)
>       ret = drm_add_edid_modes(connector, edid);
>       kfree(edid);
>  
> -     clk_disable_unprepare(hdmi->ddc_clk);
> -
>       return ret;
>  }
>  
> @@ -407,9 +323,9 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
> device *master,
>               SUN4I_HDMI_PLL_CTRL_PLL_EN;
>       writel(reg, hdmi->base + SUN4I_HDMI_PLL_CTRL_REG);
>  
> -     ret = sun4i_ddc_create(hdmi, hdmi->tmds_clk);
> +     ret = sun4i_hdmi_i2c_create(hdmi);
>       if (ret) {
> -             dev_err(dev, "Couldn't create the DDC clock\n");
> +             dev_err(dev, "Couldn't create the HDMI I2C adapter\n");
>               return ret;
>       }
>  
> @@ -422,13 +338,15 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
> device *master,
>                              NULL);
>       if (ret) {
>               dev_err(dev, "Couldn't initialise the HDMI encoder\n");
> -             return ret;
> +             goto err_del_i2c_adapter;
>       }
>  
>       hdmi->encoder.possible_crtcs = drm_of_find_possible_crtcs(drm,
>                                                                 dev->of_node);
> -     if (!hdmi->encoder.possible_crtcs)
> -             return -EPROBE_DEFER;
> +     if (!hdmi->encoder.possible_crtcs) {
> +             ret = -EPROBE_DEFER;
> +             goto err_del_i2c_adapter;
> +     }
>  
>       drm_connector_helper_add(&hdmi->connector,
>                                &sun4i_hdmi_connector_helper_funcs);
> @@ -451,6 +369,8 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
> device *master,
>  
>  err_cleanup_connector:
>       drm_encoder_cleanup(&hdmi->encoder);
> +err_del_i2c_adapter:
> +     i2c_del_adapter(hdmi->i2c);
>       return ret;
>  }
>  
> @@ -461,6 +381,7 @@ static void sun4i_hdmi_unbind(struct device *dev, struct 
> device *master,
>  
>       drm_connector_cleanup(&hdmi->connector);
>       drm_encoder_cleanup(&hdmi->encoder);
> +     i2c_del_adapter(hdmi->i2c);
>  }
>  
>  static const struct component_ops sun4i_hdmi_ops = {
> diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c 
> b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
> new file mode 100644
> index 000000000000..e82fa8a55165
> --- /dev/null
> +++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
> @@ -0,0 +1,220 @@
> +/*
> + * Copyright (C) 2017 Jonathan Liu
> + *
> + * Jonathan Liu <net...@gmail.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/i2c.h>
> +#include <linux/iopoll.h>
> +#include <linux/ktime.h>
> +
> +#include "sun4i_hdmi.h"
> +
> +#define SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK ( \
> +     SUN4I_HDMI_DDC_INT_STATUS_ILLEGAL_FIFO_OPERATION | \
> +     SUN4I_HDMI_DDC_INT_STATUS_DDC_RX_FIFO_UNDERFLOW | \
> +     SUN4I_HDMI_DDC_INT_STATUS_DDC_TX_FIFO_UNDERFLOW | \
> +     SUN4I_HDMI_DDC_INT_STATUS_ARBITRATION_ERROR | \
> +     SUN4I_HDMI_DDC_INT_STATUS_ACK_ERROR | \
> +     SUN4I_HDMI_DDC_INT_STATUS_BUS_ERROR \
> +)
> +
> +static int wait_fifo_flag_unset(struct sun4i_hdmi *hdmi, u32 flag)
> +{
> +     /* 1 byte takes 9 clock cycles (8 bits + 1 ack) */
> +     unsigned long byte_time = DIV_ROUND_UP(USEC_PER_SEC,
> +                                            clk_get_rate(hdmi->ddc_clk)) * 9;
> +     ktime_t wait_timeout = ktime_add_us(ktime_get(), 100000);
> +     u32 reg;
> +
> +     for (;;) {
> +             /* Check for errors */
> +             reg = readl(hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +             if (reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK) {
> +                     writel(reg, hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +                     return -EIO;
> +             }
> +
> +             /* Check if requested FIFO flag is unset */
> +             reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_STATUS_REG);
> +             if (!(reg & flag))
> +                     return 0;
> +
> +             /* Timeout */
> +             if (ktime_compare(ktime_get(), wait_timeout) > 0)
> +                     return -EIO;
> +
> +             /* Wait for 1-2 bytes to transfer */
> +             usleep_range(byte_time, 2 * byte_time);
> +     }
> +
> +     return -EIO;
> +}
> +
> +static int wait_fifo_read_ready(struct sun4i_hdmi *hdmi)
> +{
> +     return wait_fifo_flag_unset(hdmi, SUN4I_HDMI_DDC_FIFO_STATUS_EMPTY);
> +}
> +
> +static int wait_fifo_write_ready(struct sun4i_hdmi *hdmi)
> +{
> +     return wait_fifo_flag_unset(hdmi, SUN4I_HDMI_DDC_FIFO_STATUS_FULL);
> +}

Both of these can use readl_poll_timeout, and I'm not sure you need to
be that aggressive in your timings.

> +
> +static int xfer_msg(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
> +{
> +     u32 reg;
> +     int i;
> +
> +     reg = readl(hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +     reg &= ~SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK;
> +     writel(reg, hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +
> +     reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> +     reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
> +     reg |= (msg->flags & I2C_M_RD) ?
> +            SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ :
> +            SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE;
> +     writel(reg, hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> +
> +     writel(SUN4I_HDMI_DDC_ADDR_SLAVE(msg->addr),
> +            hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
> +
> +     reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
> +     writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
> +            hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
> +
> +     if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG,
> +                            reg,
> +                            !(reg & SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR),
> +                            100, 100000))
> +             return -EIO;
> +
> +     writel(msg->len, hdmi->base + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
> +     writel(msg->flags & I2C_M_RD ?
> +            SUN4I_HDMI_DDC_CMD_IMPLICIT_READ :
> +            SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE,
> +            hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
> +
> +     reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> +     writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
> +            hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> +
> +     if (msg->flags & I2C_M_RD) {
> +             for (i = 0; i < msg->len; i++) {
> +                     if (wait_fifo_read_ready(hdmi))
> +                             return -EIO;

it seems weird that a function called read_ready would return 1 if
there's an error.

> +
> +                     *msg->buf++ = readb(hdmi->base +
> +                                         SUN4I_HDMI_DDC_FIFO_DATA_REG);

Don't you have an hardware FIFO you can rely on intead of reading
everything byte per byte?

> +             }
> +     } else {
> +             for (i = 0; i < msg->len; i++) {
> +                     if (wait_fifo_write_ready(hdmi))
> +                             return -EIO;
> +
> +                     writeb(*msg->buf++, hdmi->base +
> +                            SUN4I_HDMI_DDC_FIFO_DATA_REG);
> +             }
> +     }
> +
> +     if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG,
> +                            reg,
> +                            !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
> +                            100, 100000))
> +             return -EIO;
> +
> +     reg = readl(hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +
> +     /* Check for errors */
> +     if ((reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK) ||
> +         !(reg & SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE)) {
> +             writel(reg, hdmi->base + SUN4I_HDMI_DDC_INT_STATUS_REG);
> +             return -EIO;
> +     }
> +
> +     return 0;
> +}
> +
> +static int sun4i_hdmi_i2c_xfer(struct i2c_adapter *adap,
> +                            struct i2c_msg *msgs, int num)
> +{
> +     struct sun4i_hdmi *hdmi = i2c_get_adapdata(adap);
> +     u32 reg;
> +     int err, i, ret = num;
> +
> +     for (i = 0; i < num; i++) {
> +             if (!msgs[i].len)
> +                     return -EINVAL;
> +             if (msgs[i].len > SUN4I_HDMI_DDC_MAX_TRANSFER_SIZE)
> +                     return -EINVAL;
> +     }
> +
> +     /* Reset I2C controller */
> +     writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
> +            hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
> +     if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
> +                            !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
> +                            100, 2000))
> +             return -EIO;
> +
> +     writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
> +            SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
> +            hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
> +
> +     clk_prepare_enable(hdmi->ddc_clk);
> +     clk_set_rate(hdmi->ddc_clk, 100000);
> +
> +     for (i = 0; i < num; i++) {
> +             err = xfer_msg(hdmi, &msgs[i]);
> +             if (err) {
> +                     ret = err;
> +                     break;
> +             }
> +     }
> +
> +     clk_disable_unprepare(hdmi->ddc_clk);
> +     return ret;
> +}
> +
> +static u32 sun4i_hdmi_i2c_func(struct i2c_adapter *adap)
> +{
> +     return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static const struct i2c_algorithm sun4i_hdmi_i2c_algorithm = {
> +     .master_xfer    = sun4i_hdmi_i2c_xfer,
> +     .functionality  = sun4i_hdmi_i2c_func,
> +};
> +
> +static struct i2c_adapter sun4i_hdmi_i2c_adapter = {
> +     .owner  = THIS_MODULE,
> +     .class  = I2C_CLASS_DDC,
> +     .algo   = &sun4i_hdmi_i2c_algorithm,
> +     .name   = "sun4i_hdmi_i2c adapter",
> +};

const?

(plus the changes mentionned in the v2 I just replied to, if they
still apply).

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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