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[v2,1/4] drm: Helper for lspcon in drm_dp_dual_mode

Message ID 1466521259-9309-2-git-send-email-shashank.sharma@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Sharma, Shashank June 21, 2016, 3 p.m. UTC
This patch adds lspcon support in dp_dual_mode helper.
lspcon is essentially a dp->hdmi dongle with dual personality.

LS mode: It works as a passive dongle, by level shifting DP++
signals to HDMI signals, in LS mode.
PCON mode: It works as a protocol converter active dongle
in pcon mode, by converting DP++ outputs to HDMI 2.0 outputs.

This patch adds support for lspcon detection and mode set
switch operations, as a dp dual mode dongle.

v2: Addressed review comments from Ville
- add adaptor id for lspcon devices (0x08), use it to identify lspcon
- change function names
  old: drm_lspcon_get_current_mode/drm_lspcon_change_mode
  new: drm_lspcon_get_mode/drm_lspcon_set_mode
- change drm_lspcon_get_mode type to int, to match
  drm_dp_dual_mode_get_tmds_output
- change 'err' to 'ret' to match the rest of the functions
- remove pointless typecasting during call to dual_mode_read
- fix the but while setting value of data, while writing lspcon mode
- fix indentation
- change mdelay(10) -> msleep(10)
- return ETIMEDOUT instead of EFAULT, when lspcon mode change times out
- Add an empty line to separate std regs macros and lspcon regs macros
  Indent bit definition

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
---
 drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103 ++++++++++++++++++++++++++++++
 include/drm/drm_dp_dual_mode_helper.h     |  25 ++++++++
 2 files changed, 128 insertions(+)

Comments

Rodrigo Vivi June 30, 2016, 10:16 p.m. UTC | #1
On Tue, Jun 21, 2016 at 8:00 AM, Shashank Sharma
<shashank.sharma@intel.com> wrote:
> This patch adds lspcon support in dp_dual_mode helper.
> lspcon is essentially a dp->hdmi dongle with dual personality.
>
> LS mode: It works as a passive dongle, by level shifting DP++
> signals to HDMI signals, in LS mode.
> PCON mode: It works as a protocol converter active dongle
> in pcon mode, by converting DP++ outputs to HDMI 2.0 outputs.
>
> This patch adds support for lspcon detection and mode set
> switch operations, as a dp dual mode dongle.
>
> v2: Addressed review comments from Ville
> - add adaptor id for lspcon devices (0x08), use it to identify lspcon
> - change function names
>   old: drm_lspcon_get_current_mode/drm_lspcon_change_mode
>   new: drm_lspcon_get_mode/drm_lspcon_set_mode
> - change drm_lspcon_get_mode type to int, to match
>   drm_dp_dual_mode_get_tmds_output
> - change 'err' to 'ret' to match the rest of the functions
> - remove pointless typecasting during call to dual_mode_read
> - fix the but while setting value of data, while writing lspcon mode
> - fix indentation
> - change mdelay(10) -> msleep(10)
> - return ETIMEDOUT instead of EFAULT, when lspcon mode change times out
> - Add an empty line to separate std regs macros and lspcon regs macros
>   Indent bit definition
>
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
>  drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103 ++++++++++++++++++++++++++++++
>  include/drm/drm_dp_dual_mode_helper.h     |  25 ++++++++
>  2 files changed, 128 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> index a7b2a75..404e715 100644
> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -148,6 +148,14 @@ static bool is_type2_adaptor(uint8_t adaptor_id)
>                               DP_DUAL_MODE_REV_TYPE2);
>  }
>
> +bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
> +       const uint8_t adaptor_id)
> +{
> +       return is_hdmi_adaptor(hdmi_id) &&
> +               (adaptor_id == (DP_DUAL_MODE_REV_TYPE2 |

DP_DUAL_MODE_REV_TYPE2 = 0 so useless here and confusing.

> +                       DP_DUAL_MODE_TYPE_TYPE2 | DP_DUAL_MODE_TYPE_LSPCON));

Also this is confusing and took me a while to uderstand that LSPCON is
the type2 with DPCD

so my suggestion is to define DP_DUAL_MODE_TYPE_HAS_DPCD (1<<3) with a
comment this is defined by LSPCON docs since this is not part of VESA
DP Dual Mode that only defines the Type2 = 0xA0.

so you could use
TYPE2 | HAS_DPCD = LSPCON.

> +}
> +
>  /**
>   * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
>   * @adapter: I2C adapter for the DDC bus
> @@ -203,6 +211,8 @@ enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>         ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
>                                     &adaptor_id, sizeof(adaptor_id));
>         if (ret == 0) {
> +               if (is_lspcon_adaptor(hdmi_id, adaptor_id))
> +                       return DRM_DP_DUAL_MODE_LSPCON;
>                 if (is_type2_adaptor(adaptor_id)) {
>                         if (is_hdmi_adaptor(hdmi_id))
>                                 return DRM_DP_DUAL_MODE_TYPE2_HDMI;
> @@ -364,3 +374,96 @@ const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
>         }
>  }
>  EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
> +
> +/**
> + * drm_lspcon_get_current_mode: Get LSPCON's current mode of operation by
> + * by reading offset (0x80, 0x41)
> + * @i2c_adapter: I2C-over-aux adapter
> + * @current_mode: out vaiable, current lspcon mode of operation
> + *
> + * Returns:
> + * 0 on success, sets the current_mode value to appropriate mode
> + * -error on failure
> + */
> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
> +       enum drm_lspcon_mode *current_mode)
> +{
> +       u8 data;
> +       int ret = 0;
> +
> +       if (!current_mode) {
> +               DRM_ERROR("NULL input\n");
> +               return -EINVAL;
> +       }
> +
> +       /* Read Status: i2c over aux */
> +       ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
> +                       (void *)&data, sizeof(data));
> +       if (ret < 0) {
> +               DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
> +               return -EFAULT;
> +       }

> +
> +       if (data & DP_DUAL_MODE_LSPCON_MODE_MASK)
> +               *current_mode = DRM_LSPCON_MODE_PCON;
> +       else
> +               *current_mode = DRM_LSPCON_MODE_LS;
> +       return 0;
> +}
> +EXPORT_SYMBOL(drm_lspcon_get_mode);
> +
> +/**
> + * drm_lspcon_change_mode: Change LSPCON's mode of operation by
> + * by writing offset (0x80, 0x40)
> + * @i2c_adapter: I2C-over-aux adapter
> + * @reqd_mode: required mode of operation
> + *
> + * Returns:
> + * 0 on success, -error on failure/timeout
> + */
> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
> +       enum drm_lspcon_mode reqd_mode)
> +{
> +       u8 data = 0;
> +       int ret;
> +       int time_out = 200;
> +       enum drm_lspcon_mode changed_mode;
> +
> +       if (reqd_mode == DRM_LSPCON_MODE_PCON)
> +               data = DP_DUAL_MODE_LSPCON_MODE_MASK;
> +
> +       /* Change mode */
> +       ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
> +                       &data, sizeof(data));
> +       if (ret < 0) {
> +               DRM_ERROR("LSPCON mode change failed\n");
> +               return ret;
> +       }
> +
> +       /*
> +         * Confirm mode change by reading the status bit.
> +         * Sometimes, it takes a while to change the mode,
> +         * so wait and retry until time out or done.
> +         */
> +       do {
> +               ret = drm_lspcon_get_mode(adapter, &changed_mode);
> +               if (ret) {
> +                       DRM_ERROR("cant confirm LSPCON mode change\n");
> +                       return ret;
> +               } else {
> +                       if (changed_mode != reqd_mode) {
> +                               msleep(10);
> +                               time_out -= 10;
> +                       } else {
> +                               DRM_DEBUG_KMS("LSPCON mode changed to %s\n",
> +                                       reqd_mode == DRM_LSPCON_MODE_LS ?
> +                                               "LS" : "PCON");
> +                               return 0;
> +                       }
> +               }
> +       } while (time_out);
> +
> +       DRM_ERROR("LSPCON mode change timed out\n");
> +       return -ETIMEDOUT;
> +}
> +EXPORT_SYMBOL(drm_lspcon_set_mode);
> diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
> index e8a9dfd..441c6cb 100644
> --- a/include/drm/drm_dp_dual_mode_helper.h
> +++ b/include/drm/drm_dp_dual_mode_helper.h
> @@ -24,6 +24,7 @@
>  #define DRM_DP_DUAL_MODE_HELPER_H
>
>  #include <linux/types.h>
> +#include <drm/drm_edid.h>
>
>  /*
>   * Optional for type 1 DVI adaptors
> @@ -40,6 +41,7 @@
>  #define  DP_DUAL_MODE_REV_TYPE2 0x00
>  #define  DP_DUAL_MODE_TYPE_MASK 0xf0
>  #define  DP_DUAL_MODE_TYPE_TYPE2 0xa0
> +#define  DP_DUAL_MODE_TYPE_LSPCON 0x08
>  #define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
>  #define  DP_DUAL_IEEE_OUI_LEN 3
>  #define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
> @@ -55,6 +57,10 @@
>  #define  DP_DUAL_MODE_CEC_ENABLE 0x01
>  #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
>
> +#define DP_DUAL_MODE_LSPCON_MODE_CHANGE                0x40
> +#define DP_DUAL_MODE_LSPCON_CURRENT_MODE               0x41

Where did you get this from? I haven't seen any offset 80, adress 41
defined anywhere in any of the docs I have here. What am I missing?

> +#define  DP_DUAL_MODE_LSPCON_MODE_MASK                 0x1

I don't believe "mask" is a good term here....

probably
DP_DUAL_MODE_LSPCON_MODE_PCON (1<<0)

> +
>  struct i2c_adapter;
>
>  ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
> @@ -63,6 +69,19 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
>                                u8 offset, const void *buffer, size_t size);
>
>  /**
> +* enum drm_lspcon_mode
> +* @lspcon_mode_ls: Level shifter mode of LSPCON
> +*      which drives DP++ to HDMI 1.4 conversion.
> +* @lspcon_mode_pcon: Protocol converter mode of LSPCON
> +*      which drives DP++ to HDMI 2.0 active conversion.
> +*/
> +enum drm_lspcon_mode {
> +       DRM_LSPCON_MODE_INVALID,
> +       DRM_LSPCON_MODE_LS,
> +       DRM_LSPCON_MODE_PCON,
> +};
> +
> +/**
>   * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
>   * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
>   * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI adaptor
> @@ -70,6 +89,7 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
>   * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
>   * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
>   * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
> + * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
>   */
>  enum drm_dp_dual_mode_type {
>         DRM_DP_DUAL_MODE_NONE,
> @@ -78,6 +98,7 @@ enum drm_dp_dual_mode_type {
>         DRM_DP_DUAL_MODE_TYPE1_HDMI,
>         DRM_DP_DUAL_MODE_TYPE2_DVI,
>         DRM_DP_DUAL_MODE_TYPE2_HDMI,
> +       DRM_DP_DUAL_MODE_LSPCON,
>  };
>
>  enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter);
> @@ -89,4 +110,8 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
>                                      struct i2c_adapter *adapter, bool enable);
>  const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type);
>
> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
> +       enum drm_lspcon_mode *current_mode);
> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
> +               enum drm_lspcon_mode reqd_mode);
>  #endif
> --
> 1.9.1
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Sharma, Shashank July 1, 2016, 5:58 a.m. UTC | #2
Thanks for the review Rodrigo. My comments inline.

Regards
Shashank

On 7/1/2016 3:46 AM, Rodrigo Vivi wrote:
> On Tue, Jun 21, 2016 at 8:00 AM, Shashank Sharma
> <shashank.sharma@intel.com> wrote:
>> This patch adds lspcon support in dp_dual_mode helper.
>> lspcon is essentially a dp->hdmi dongle with dual personality.
>>
>> LS mode: It works as a passive dongle, by level shifting DP++
>> signals to HDMI signals, in LS mode.
>> PCON mode: It works as a protocol converter active dongle
>> in pcon mode, by converting DP++ outputs to HDMI 2.0 outputs.
>>
>> This patch adds support for lspcon detection and mode set
>> switch operations, as a dp dual mode dongle.
>>
>> v2: Addressed review comments from Ville
>> - add adaptor id for lspcon devices (0x08), use it to identify lspcon
>> - change function names
>>    old: drm_lspcon_get_current_mode/drm_lspcon_change_mode
>>    new: drm_lspcon_get_mode/drm_lspcon_set_mode
>> - change drm_lspcon_get_mode type to int, to match
>>    drm_dp_dual_mode_get_tmds_output
>> - change 'err' to 'ret' to match the rest of the functions
>> - remove pointless typecasting during call to dual_mode_read
>> - fix the but while setting value of data, while writing lspcon mode
>> - fix indentation
>> - change mdelay(10) -> msleep(10)
>> - return ETIMEDOUT instead of EFAULT, when lspcon mode change times out
>> - Add an empty line to separate std regs macros and lspcon regs macros
>>    Indent bit definition
>>
>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>> ---
>>   drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103 ++++++++++++++++++++++++++++++
>>   include/drm/drm_dp_dual_mode_helper.h     |  25 ++++++++
>>   2 files changed, 128 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> index a7b2a75..404e715 100644
>> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>> @@ -148,6 +148,14 @@ static bool is_type2_adaptor(uint8_t adaptor_id)
>>                                DP_DUAL_MODE_REV_TYPE2);
>>   }
>>
>> +bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
>> +       const uint8_t adaptor_id)
>> +{
>> +       return is_hdmi_adaptor(hdmi_id) &&
>> +               (adaptor_id == (DP_DUAL_MODE_REV_TYPE2 |
>
> DP_DUAL_MODE_REV_TYPE2 = 0 so useless here and confusing.
This was a review comment from Ville, on the last patch. I think he 
suggested for the better readability of the code.
>
>> +                       DP_DUAL_MODE_TYPE_TYPE2 | DP_DUAL_MODE_TYPE_LSPCON));
>
> Also this is confusing and took me a while to uderstand that LSPCON is
> the type2 with DPCD
I know, due to LSPCON's dual personality, its complicated to understand. 
I tried to cover some theory, in the cover letter, can add some here too:
LSPCON is a dp->hdmi adapter which can operate in two modes
Passive dongle mode / LS mode: in this mode, it acts as type2 dp dual 
mode adapter (no DPCD readable here)
Active mode / PCON mode: in this mode, it acts as active DP++->HDMI2.0 
protocol convertor dongle, and allows DPCD read/write like a DP++ display.
>
> so my suggestion is to define DP_DUAL_MODE_TYPE_HAS_DPCD (1<<3) with a
> comment this is defined by LSPCON docs since this is not part of VESA
> DP Dual Mode that only defines the Type2 = 0xA0.
>
> so you could use
> TYPE2 | HAS_DPCD = LSPCON.
>
Sure, got it. Will change it like this.
>> +}
>> +
>>   /**
>>    * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
>>    * @adapter: I2C adapter for the DDC bus
>> @@ -203,6 +211,8 @@ enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>>          ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
>>                                      &adaptor_id, sizeof(adaptor_id));
>>          if (ret == 0) {
>> +               if (is_lspcon_adaptor(hdmi_id, adaptor_id))
>> +                       return DRM_DP_DUAL_MODE_LSPCON;
>>                  if (is_type2_adaptor(adaptor_id)) {
>>                          if (is_hdmi_adaptor(hdmi_id))
>>                                  return DRM_DP_DUAL_MODE_TYPE2_HDMI;
>> @@ -364,3 +374,96 @@ const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
>>          }
>>   }
>>   EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
>> +
>> +/**
>> + * drm_lspcon_get_current_mode: Get LSPCON's current mode of operation by
>> + * by reading offset (0x80, 0x41)
>> + * @i2c_adapter: I2C-over-aux adapter
>> + * @current_mode: out vaiable, current lspcon mode of operation
>> + *
>> + * Returns:
>> + * 0 on success, sets the current_mode value to appropriate mode
>> + * -error on failure
>> + */
>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>> +       enum drm_lspcon_mode *current_mode)
>> +{
>> +       u8 data;
>> +       int ret = 0;
>> +
>> +       if (!current_mode) {
>> +               DRM_ERROR("NULL input\n");
>> +               return -EINVAL;
>> +       }
>> +
>> +       /* Read Status: i2c over aux */
>> +       ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
>> +                       (void *)&data, sizeof(data));
>> +       if (ret < 0) {
>> +               DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
>> +               return -EFAULT;
>> +       }
>
>> +
>> +       if (data & DP_DUAL_MODE_LSPCON_MODE_MASK)
>> +               *current_mode = DRM_LSPCON_MODE_PCON;
>> +       else
>> +               *current_mode = DRM_LSPCON_MODE_LS;
>> +       return 0;
>> +}
>> +EXPORT_SYMBOL(drm_lspcon_get_mode);
>> +
>> +/**
>> + * drm_lspcon_change_mode: Change LSPCON's mode of operation by
>> + * by writing offset (0x80, 0x40)
>> + * @i2c_adapter: I2C-over-aux adapter
>> + * @reqd_mode: required mode of operation
>> + *
>> + * Returns:
>> + * 0 on success, -error on failure/timeout
>> + */
>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>> +       enum drm_lspcon_mode reqd_mode)
>> +{
>> +       u8 data = 0;
>> +       int ret;
>> +       int time_out = 200;
>> +       enum drm_lspcon_mode changed_mode;
>> +
>> +       if (reqd_mode == DRM_LSPCON_MODE_PCON)
>> +               data = DP_DUAL_MODE_LSPCON_MODE_MASK;
>> +
>> +       /* Change mode */
>> +       ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
>> +                       &data, sizeof(data));
>> +       if (ret < 0) {
>> +               DRM_ERROR("LSPCON mode change failed\n");
>> +               return ret;
>> +       }
>> +
>> +       /*
>> +         * Confirm mode change by reading the status bit.
>> +         * Sometimes, it takes a while to change the mode,
>> +         * so wait and retry until time out or done.
>> +         */
>> +       do {
>> +               ret = drm_lspcon_get_mode(adapter, &changed_mode);
>> +               if (ret) {
>> +                       DRM_ERROR("cant confirm LSPCON mode change\n");
>> +                       return ret;
>> +               } else {
>> +                       if (changed_mode != reqd_mode) {
>> +                               msleep(10);
>> +                               time_out -= 10;
>> +                       } else {
>> +                               DRM_DEBUG_KMS("LSPCON mode changed to %s\n",
>> +                                       reqd_mode == DRM_LSPCON_MODE_LS ?
>> +                                               "LS" : "PCON");
>> +                               return 0;
>> +                       }
>> +               }
>> +       } while (time_out);
>> +
>> +       DRM_ERROR("LSPCON mode change timed out\n");
>> +       return -ETIMEDOUT;
>> +}
>> +EXPORT_SYMBOL(drm_lspcon_set_mode);
>> diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
>> index e8a9dfd..441c6cb 100644
>> --- a/include/drm/drm_dp_dual_mode_helper.h
>> +++ b/include/drm/drm_dp_dual_mode_helper.h
>> @@ -24,6 +24,7 @@
>>   #define DRM_DP_DUAL_MODE_HELPER_H
>>
>>   #include <linux/types.h>
>> +#include <drm/drm_edid.h>
>>
>>   /*
>>    * Optional for type 1 DVI adaptors
>> @@ -40,6 +41,7 @@
>>   #define  DP_DUAL_MODE_REV_TYPE2 0x00
>>   #define  DP_DUAL_MODE_TYPE_MASK 0xf0
>>   #define  DP_DUAL_MODE_TYPE_TYPE2 0xa0
>> +#define  DP_DUAL_MODE_TYPE_LSPCON 0x08
>>   #define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
>>   #define  DP_DUAL_IEEE_OUI_LEN 3
>>   #define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
>> @@ -55,6 +57,10 @@
>>   #define  DP_DUAL_MODE_CEC_ENABLE 0x01
>>   #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
>>
>> +#define DP_DUAL_MODE_LSPCON_MODE_CHANGE                0x40
>> +#define DP_DUAL_MODE_LSPCON_CURRENT_MODE               0x41
>
> Where did you get this from? I haven't seen any offset 80, adress 41
> defined anywhere in any of the docs I have here. What am I missing?
>
This offset was added by MCA after Intel requested them to confirm the 
LSPCON modeset success. Initially they gave us just 0x40, which is to 
request a change in mode from LS->PCON or other way. But we saw many 
times this change was not happening, so Intel requested MCA to have 
another register offset (0x41) to confirm the current LSPCON mode.
I dont have an updated MCA doc on this, but I can arrange if you insist 
on this.
>> +#define  DP_DUAL_MODE_LSPCON_MODE_MASK                 0x1
>
> I don't believe "mask" is a good term here....
>
> probably
> DP_DUAL_MODE_LSPCON_MODE_PCON (1<<0)
Agree, will change it to something as you suggested

Shashank
>
>> +
>>   struct i2c_adapter;
>>
>>   ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
>> @@ -63,6 +69,19 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
>>                                 u8 offset, const void *buffer, size_t size);
>>
>>   /**
>> +* enum drm_lspcon_mode
>> +* @lspcon_mode_ls: Level shifter mode of LSPCON
>> +*      which drives DP++ to HDMI 1.4 conversion.
>> +* @lspcon_mode_pcon: Protocol converter mode of LSPCON
>> +*      which drives DP++ to HDMI 2.0 active conversion.
>> +*/
>> +enum drm_lspcon_mode {
>> +       DRM_LSPCON_MODE_INVALID,
>> +       DRM_LSPCON_MODE_LS,
>> +       DRM_LSPCON_MODE_PCON,
>> +};
>> +
>> +/**
>>    * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
>>    * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
>>    * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI adaptor
>> @@ -70,6 +89,7 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
>>    * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
>>    * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
>>    * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
>> + * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
>>    */
>>   enum drm_dp_dual_mode_type {
>>          DRM_DP_DUAL_MODE_NONE,
>> @@ -78,6 +98,7 @@ enum drm_dp_dual_mode_type {
>>          DRM_DP_DUAL_MODE_TYPE1_HDMI,
>>          DRM_DP_DUAL_MODE_TYPE2_DVI,
>>          DRM_DP_DUAL_MODE_TYPE2_HDMI,
>> +       DRM_DP_DUAL_MODE_LSPCON,
>>   };
>>
>>   enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter);
>> @@ -89,4 +110,8 @@ int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
>>                                       struct i2c_adapter *adapter, bool enable);
>>   const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type);
>>
>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>> +       enum drm_lspcon_mode *current_mode);
>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>> +               enum drm_lspcon_mode reqd_mode);
>>   #endif
>> --
>> 1.9.1
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
>
>
Rodrigo Vivi July 1, 2016, 2:11 p.m. UTC | #3
On Thu, Jun 30, 2016 at 10:58 PM, Sharma, Shashank
<shashank.sharma@intel.com> wrote:
> Thanks for the review Rodrigo. My comments inline.
>
> Regards
> Shashank
>
>
> On 7/1/2016 3:46 AM, Rodrigo Vivi wrote:
>>
>> On Tue, Jun 21, 2016 at 8:00 AM, Shashank Sharma
>> <shashank.sharma@intel.com> wrote:
>>>
>>> This patch adds lspcon support in dp_dual_mode helper.
>>> lspcon is essentially a dp->hdmi dongle with dual personality.
>>>
>>> LS mode: It works as a passive dongle, by level shifting DP++
>>> signals to HDMI signals, in LS mode.
>>> PCON mode: It works as a protocol converter active dongle
>>> in pcon mode, by converting DP++ outputs to HDMI 2.0 outputs.
>>>
>>> This patch adds support for lspcon detection and mode set
>>> switch operations, as a dp dual mode dongle.
>>>
>>> v2: Addressed review comments from Ville
>>> - add adaptor id for lspcon devices (0x08), use it to identify lspcon
>>> - change function names
>>>    old: drm_lspcon_get_current_mode/drm_lspcon_change_mode
>>>    new: drm_lspcon_get_mode/drm_lspcon_set_mode
>>> - change drm_lspcon_get_mode type to int, to match
>>>    drm_dp_dual_mode_get_tmds_output
>>> - change 'err' to 'ret' to match the rest of the functions
>>> - remove pointless typecasting during call to dual_mode_read
>>> - fix the but while setting value of data, while writing lspcon mode
>>> - fix indentation
>>> - change mdelay(10) -> msleep(10)
>>> - return ETIMEDOUT instead of EFAULT, when lspcon mode change times out
>>> - Add an empty line to separate std regs macros and lspcon regs macros
>>>    Indent bit definition
>>>
>>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>>> ---
>>>   drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103
>>> ++++++++++++++++++++++++++++++
>>>   include/drm/drm_dp_dual_mode_helper.h     |  25 ++++++++
>>>   2 files changed, 128 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> index a7b2a75..404e715 100644
>>> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> @@ -148,6 +148,14 @@ static bool is_type2_adaptor(uint8_t adaptor_id)
>>>                                DP_DUAL_MODE_REV_TYPE2);
>>>   }
>>>
>>> +bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
>>> +       const uint8_t adaptor_id)
>>> +{
>>> +       return is_hdmi_adaptor(hdmi_id) &&
>>> +               (adaptor_id == (DP_DUAL_MODE_REV_TYPE2 |
>>
>>
>> DP_DUAL_MODE_REV_TYPE2 = 0 so useless here and confusing.
>
> This was a review comment from Ville, on the last patch. I think he
> suggested for the better readability of the code.
>>
>>
>>> +                       DP_DUAL_MODE_TYPE_TYPE2 |
>>> DP_DUAL_MODE_TYPE_LSPCON));
>>
>>
>> Also this is confusing and took me a while to uderstand that LSPCON is
>> the type2 with DPCD
>
> I know, due to LSPCON's dual personality, its complicated to understand. I
> tried to cover some theory, in the cover letter, can add some here too:
> LSPCON is a dp->hdmi adapter which can operate in two modes
> Passive dongle mode / LS mode: in this mode, it acts as type2 dp dual mode
> adapter (no DPCD readable here)
> Active mode / PCON mode: in this mode, it acts as active DP++->HDMI2.0
> protocol convertor dongle, and allows DPCD read/write like a DP++ display.
>>
>>
>> so my suggestion is to define DP_DUAL_MODE_TYPE_HAS_DPCD (1<<3) with a
>> comment this is defined by LSPCON docs since this is not part of VESA
>> DP Dual Mode that only defines the Type2 = 0xA0.
>>
>> so you could use
>> TYPE2 | HAS_DPCD = LSPCON.
>>
> Sure, got it. Will change it like this.
>
>>> +}
>>> +
>>>   /**
>>>    * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
>>>    * @adapter: I2C adapter for the DDC bus
>>> @@ -203,6 +211,8 @@ enum drm_dp_dual_mode_type
>>> drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>>>          ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
>>>                                      &adaptor_id, sizeof(adaptor_id));
>>>          if (ret == 0) {
>>> +               if (is_lspcon_adaptor(hdmi_id, adaptor_id))
>>> +                       return DRM_DP_DUAL_MODE_LSPCON;
>>>                  if (is_type2_adaptor(adaptor_id)) {
>>>                          if (is_hdmi_adaptor(hdmi_id))
>>>                                  return DRM_DP_DUAL_MODE_TYPE2_HDMI;
>>> @@ -364,3 +374,96 @@ const char *drm_dp_get_dual_mode_type_name(enum
>>> drm_dp_dual_mode_type type)
>>>          }
>>>   }
>>>   EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
>>> +
>>> +/**
>>> + * drm_lspcon_get_current_mode: Get LSPCON's current mode of operation
>>> by
>>> + * by reading offset (0x80, 0x41)
>>> + * @i2c_adapter: I2C-over-aux adapter
>>> + * @current_mode: out vaiable, current lspcon mode of operation
>>> + *
>>> + * Returns:
>>> + * 0 on success, sets the current_mode value to appropriate mode
>>> + * -error on failure
>>> + */
>>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>>> +       enum drm_lspcon_mode *current_mode)
>>> +{
>>> +       u8 data;
>>> +       int ret = 0;
>>> +
>>> +       if (!current_mode) {
>>> +               DRM_ERROR("NULL input\n");
>>> +               return -EINVAL;
>>> +       }
>>> +
>>> +       /* Read Status: i2c over aux */
>>> +       ret = drm_dp_dual_mode_read(adapter,
>>> DP_DUAL_MODE_LSPCON_CURRENT_MODE,
>>> +                       (void *)&data, sizeof(data));
>>> +       if (ret < 0) {
>>> +               DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
>>> +               return -EFAULT;
>>> +       }
>>
>>
>>> +
>>> +       if (data & DP_DUAL_MODE_LSPCON_MODE_MASK)
>>> +               *current_mode = DRM_LSPCON_MODE_PCON;
>>> +       else
>>> +               *current_mode = DRM_LSPCON_MODE_LS;
>>> +       return 0;
>>> +}
>>> +EXPORT_SYMBOL(drm_lspcon_get_mode);
>>> +
>>> +/**
>>> + * drm_lspcon_change_mode: Change LSPCON's mode of operation by
>>> + * by writing offset (0x80, 0x40)
>>> + * @i2c_adapter: I2C-over-aux adapter
>>> + * @reqd_mode: required mode of operation
>>> + *
>>> + * Returns:
>>> + * 0 on success, -error on failure/timeout
>>> + */
>>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>>> +       enum drm_lspcon_mode reqd_mode)
>>> +{
>>> +       u8 data = 0;
>>> +       int ret;
>>> +       int time_out = 200;
>>> +       enum drm_lspcon_mode changed_mode;
>>> +
>>> +       if (reqd_mode == DRM_LSPCON_MODE_PCON)
>>> +               data = DP_DUAL_MODE_LSPCON_MODE_MASK;
>>> +
>>> +       /* Change mode */
>>> +       ret = drm_dp_dual_mode_write(adapter,
>>> DP_DUAL_MODE_LSPCON_MODE_CHANGE,
>>> +                       &data, sizeof(data));
>>> +       if (ret < 0) {
>>> +               DRM_ERROR("LSPCON mode change failed\n");
>>> +               return ret;
>>> +       }
>>> +
>>> +       /*
>>> +         * Confirm mode change by reading the status bit.
>>> +         * Sometimes, it takes a while to change the mode,
>>> +         * so wait and retry until time out or done.
>>> +         */
>>> +       do {
>>> +               ret = drm_lspcon_get_mode(adapter, &changed_mode);
>>> +               if (ret) {
>>> +                       DRM_ERROR("cant confirm LSPCON mode change\n");
>>> +                       return ret;
>>> +               } else {
>>> +                       if (changed_mode != reqd_mode) {
>>> +                               msleep(10);
>>> +                               time_out -= 10;
>>> +                       } else {
>>> +                               DRM_DEBUG_KMS("LSPCON mode changed to
>>> %s\n",
>>> +                                       reqd_mode == DRM_LSPCON_MODE_LS ?
>>> +                                               "LS" : "PCON");
>>> +                               return 0;
>>> +                       }
>>> +               }
>>> +       } while (time_out);
>>> +
>>> +       DRM_ERROR("LSPCON mode change timed out\n");
>>> +       return -ETIMEDOUT;
>>> +}
>>> +EXPORT_SYMBOL(drm_lspcon_set_mode);
>>> diff --git a/include/drm/drm_dp_dual_mode_helper.h
>>> b/include/drm/drm_dp_dual_mode_helper.h
>>> index e8a9dfd..441c6cb 100644
>>> --- a/include/drm/drm_dp_dual_mode_helper.h
>>> +++ b/include/drm/drm_dp_dual_mode_helper.h
>>> @@ -24,6 +24,7 @@
>>>   #define DRM_DP_DUAL_MODE_HELPER_H
>>>
>>>   #include <linux/types.h>
>>> +#include <drm/drm_edid.h>
>>>
>>>   /*
>>>    * Optional for type 1 DVI adaptors
>>> @@ -40,6 +41,7 @@
>>>   #define  DP_DUAL_MODE_REV_TYPE2 0x00
>>>   #define  DP_DUAL_MODE_TYPE_MASK 0xf0
>>>   #define  DP_DUAL_MODE_TYPE_TYPE2 0xa0
>>> +#define  DP_DUAL_MODE_TYPE_LSPCON 0x08
>>>   #define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
>>>   #define  DP_DUAL_IEEE_OUI_LEN 3
>>>   #define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
>>> @@ -55,6 +57,10 @@
>>>   #define  DP_DUAL_MODE_CEC_ENABLE 0x01
>>>   #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
>>>
>>> +#define DP_DUAL_MODE_LSPCON_MODE_CHANGE                0x40
>>> +#define DP_DUAL_MODE_LSPCON_CURRENT_MODE               0x41
>>
>>
>> Where did you get this from? I haven't seen any offset 80, adress 41
>> defined anywhere in any of the docs I have here. What am I missing?
>>
> This offset was added by MCA after Intel requested them to confirm the
> LSPCON modeset success. Initially they gave us just 0x40, which is to
> request a change in mode from LS->PCON or other way. But we saw many times
> this change was not happening, so Intel requested MCA to have another
> register offset (0x41) to confirm the current LSPCON mode.
> I dont have an updated MCA doc on this, but I can arrange if you insist on
> this.

No, I won't insist. I take your world, but I believe it worth a
comment in the code explaining it in case some future reader find the
old spec we have.

>>>
>>> +#define  DP_DUAL_MODE_LSPCON_MODE_MASK                 0x1
>>
>>
>> I don't believe "mask" is a good term here....
>>
>> probably
>> DP_DUAL_MODE_LSPCON_MODE_PCON (1<<0)
>
> Agree, will change it to something as you suggested
>
> Shashank
>
>>
>>> +
>>>   struct i2c_adapter;
>>>
>>>   ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
>>> @@ -63,6 +69,19 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter
>>> *adapter,
>>>                                 u8 offset, const void *buffer, size_t
>>> size);
>>>
>>>   /**
>>> +* enum drm_lspcon_mode
>>> +* @lspcon_mode_ls: Level shifter mode of LSPCON
>>> +*      which drives DP++ to HDMI 1.4 conversion.
>>> +* @lspcon_mode_pcon: Protocol converter mode of LSPCON
>>> +*      which drives DP++ to HDMI 2.0 active conversion.
>>> +*/
>>> +enum drm_lspcon_mode {
>>> +       DRM_LSPCON_MODE_INVALID,
>>> +       DRM_LSPCON_MODE_LS,
>>> +       DRM_LSPCON_MODE_PCON,
>>> +};
>>> +
>>> +/**
>>>    * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
>>>    * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
>>>    * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI
>>> adaptor
>>> @@ -70,6 +89,7 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter
>>> *adapter,
>>>    * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
>>>    * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
>>>    * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
>>> + * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
>>>    */
>>>   enum drm_dp_dual_mode_type {
>>>          DRM_DP_DUAL_MODE_NONE,
>>> @@ -78,6 +98,7 @@ enum drm_dp_dual_mode_type {
>>>          DRM_DP_DUAL_MODE_TYPE1_HDMI,
>>>          DRM_DP_DUAL_MODE_TYPE2_DVI,
>>>          DRM_DP_DUAL_MODE_TYPE2_HDMI,
>>> +       DRM_DP_DUAL_MODE_LSPCON,
>>>   };
>>>
>>>   enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter
>>> *adapter);
>>> @@ -89,4 +110,8 @@ int drm_dp_dual_mode_set_tmds_output(enum
>>> drm_dp_dual_mode_type type,
>>>                                       struct i2c_adapter *adapter, bool
>>> enable);
>>>   const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type
>>> type);
>>>
>>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>>> +       enum drm_lspcon_mode *current_mode);
>>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>>> +               enum drm_lspcon_mode reqd_mode);
>>>   #endif
>>> --
>>> 1.9.1
>>>
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>>
>>
>>
>
diff mbox

Patch

diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
index a7b2a75..404e715 100644
--- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
+++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
@@ -148,6 +148,14 @@  static bool is_type2_adaptor(uint8_t adaptor_id)
 			      DP_DUAL_MODE_REV_TYPE2);
 }
 
+bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
+	const uint8_t adaptor_id)
+{
+	return is_hdmi_adaptor(hdmi_id) &&
+		(adaptor_id == (DP_DUAL_MODE_REV_TYPE2 |
+			DP_DUAL_MODE_TYPE_TYPE2 | DP_DUAL_MODE_TYPE_LSPCON));
+}
+
 /**
  * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
  * @adapter: I2C adapter for the DDC bus
@@ -203,6 +211,8 @@  enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
 	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
 				    &adaptor_id, sizeof(adaptor_id));
 	if (ret == 0) {
+		if (is_lspcon_adaptor(hdmi_id, adaptor_id))
+			return DRM_DP_DUAL_MODE_LSPCON;
 		if (is_type2_adaptor(adaptor_id)) {
 			if (is_hdmi_adaptor(hdmi_id))
 				return DRM_DP_DUAL_MODE_TYPE2_HDMI;
@@ -364,3 +374,96 @@  const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type)
 	}
 }
 EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
+
+/**
+ * drm_lspcon_get_current_mode: Get LSPCON's current mode of operation by
+ * by reading offset (0x80, 0x41)
+ * @i2c_adapter: I2C-over-aux adapter
+ * @current_mode: out vaiable, current lspcon mode of operation
+ *
+ * Returns:
+ * 0 on success, sets the current_mode value to appropriate mode
+ * -error on failure
+ */
+int drm_lspcon_get_mode(struct i2c_adapter *adapter,
+	enum drm_lspcon_mode *current_mode)
+{
+	u8 data;
+	int ret = 0;
+
+	if (!current_mode) {
+		DRM_ERROR("NULL input\n");
+		return -EINVAL;
+	}
+
+	/* Read Status: i2c over aux */
+	ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_LSPCON_CURRENT_MODE,
+			(void *)&data, sizeof(data));
+	if (ret < 0) {
+		DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
+		return -EFAULT;
+	}
+
+	if (data & DP_DUAL_MODE_LSPCON_MODE_MASK)
+		*current_mode = DRM_LSPCON_MODE_PCON;
+	else
+		*current_mode = DRM_LSPCON_MODE_LS;
+	return 0;
+}
+EXPORT_SYMBOL(drm_lspcon_get_mode);
+
+/**
+ * drm_lspcon_change_mode: Change LSPCON's mode of operation by
+ * by writing offset (0x80, 0x40)
+ * @i2c_adapter: I2C-over-aux adapter
+ * @reqd_mode: required mode of operation
+ *
+ * Returns:
+ * 0 on success, -error on failure/timeout
+ */
+int drm_lspcon_set_mode(struct i2c_adapter *adapter,
+	enum drm_lspcon_mode reqd_mode)
+{
+	u8 data = 0;
+	int ret;
+	int time_out = 200;
+	enum drm_lspcon_mode changed_mode;
+
+	if (reqd_mode == DRM_LSPCON_MODE_PCON)
+		data = DP_DUAL_MODE_LSPCON_MODE_MASK;
+
+	/* Change mode */
+	ret = drm_dp_dual_mode_write(adapter, DP_DUAL_MODE_LSPCON_MODE_CHANGE,
+			&data, sizeof(data));
+	if (ret < 0) {
+		DRM_ERROR("LSPCON mode change failed\n");
+		return ret;
+	}
+
+	/*
+	  * Confirm mode change by reading the status bit.
+	  * Sometimes, it takes a while to change the mode,
+	  * so wait and retry until time out or done.
+	  */
+	do {
+		ret = drm_lspcon_get_mode(adapter, &changed_mode);
+		if (ret) {
+			DRM_ERROR("cant confirm LSPCON mode change\n");
+			return ret;
+		} else {
+			if (changed_mode != reqd_mode) {
+				msleep(10);
+				time_out -= 10;
+			} else {
+				DRM_DEBUG_KMS("LSPCON mode changed to %s\n",
+					reqd_mode == DRM_LSPCON_MODE_LS ?
+						"LS" : "PCON");
+				return 0;
+			}
+		}
+	} while (time_out);
+
+	DRM_ERROR("LSPCON mode change timed out\n");
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL(drm_lspcon_set_mode);
diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
index e8a9dfd..441c6cb 100644
--- a/include/drm/drm_dp_dual_mode_helper.h
+++ b/include/drm/drm_dp_dual_mode_helper.h
@@ -24,6 +24,7 @@ 
 #define DRM_DP_DUAL_MODE_HELPER_H
 
 #include <linux/types.h>
+#include <drm/drm_edid.h>
 
 /*
  * Optional for type 1 DVI adaptors
@@ -40,6 +41,7 @@ 
 #define  DP_DUAL_MODE_REV_TYPE2 0x00
 #define  DP_DUAL_MODE_TYPE_MASK 0xf0
 #define  DP_DUAL_MODE_TYPE_TYPE2 0xa0
+#define  DP_DUAL_MODE_TYPE_LSPCON 0x08
 #define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
 #define  DP_DUAL_IEEE_OUI_LEN 3
 #define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
@@ -55,6 +57,10 @@ 
 #define  DP_DUAL_MODE_CEC_ENABLE 0x01
 #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
 
+#define DP_DUAL_MODE_LSPCON_MODE_CHANGE		0x40
+#define DP_DUAL_MODE_LSPCON_CURRENT_MODE		0x41
+#define  DP_DUAL_MODE_LSPCON_MODE_MASK			0x1
+
 struct i2c_adapter;
 
 ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
@@ -63,6 +69,19 @@  ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
 			       u8 offset, const void *buffer, size_t size);
 
 /**
+* enum drm_lspcon_mode
+* @lspcon_mode_ls: Level shifter mode of LSPCON
+*	which drives DP++ to HDMI 1.4 conversion.
+* @lspcon_mode_pcon: Protocol converter mode of LSPCON
+*	which drives DP++ to HDMI 2.0 active conversion.
+*/
+enum drm_lspcon_mode {
+	DRM_LSPCON_MODE_INVALID,
+	DRM_LSPCON_MODE_LS,
+	DRM_LSPCON_MODE_PCON,
+};
+
+/**
  * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
  * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
  * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI adaptor
@@ -70,6 +89,7 @@  ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
  * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
  * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
  * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
+ * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
  */
 enum drm_dp_dual_mode_type {
 	DRM_DP_DUAL_MODE_NONE,
@@ -78,6 +98,7 @@  enum drm_dp_dual_mode_type {
 	DRM_DP_DUAL_MODE_TYPE1_HDMI,
 	DRM_DP_DUAL_MODE_TYPE2_DVI,
 	DRM_DP_DUAL_MODE_TYPE2_HDMI,
+	DRM_DP_DUAL_MODE_LSPCON,
 };
 
 enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter);
@@ -89,4 +110,8 @@  int drm_dp_dual_mode_set_tmds_output(enum drm_dp_dual_mode_type type,
 				     struct i2c_adapter *adapter, bool enable);
 const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type);
 
+int drm_lspcon_get_mode(struct i2c_adapter *adapter,
+	enum drm_lspcon_mode *current_mode);
+int drm_lspcon_set_mode(struct i2c_adapter *adapter,
+		enum drm_lspcon_mode reqd_mode);
 #endif