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

Rodrigo Vivi
2016-06-30T22:16:05Z

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
>
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--
Rodrigo Vivi
Blog: http://blog.vivi.eng.br