[PATCH v2] drm: Print some debug/error info during DP dual mode detect

[Sean Paul]

On Wed, Oct 26, 2016 at 12:29 PM, Imre Deak <imre.deak at intel.com> wrote:
> There's at least one LSPCON device that occasionally returns an unexpected
> adaptor ID which leads to a failed detect. Print some debug info to help
> debugging this and future cases. Also print an error for an unexpected
> adaptor ID, so users can report it.
>
> v2:
> - s/adapter/adaptor/ and add code comment about incorrect type 1 adaptor
>   IDs. (Ville)
>
> Cc: dri-devel at lists.freedesktop.org
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>


Applied to drm-misc, thanks

Sean

> ---
>  drivers/gpu/drm/drm_dp_dual_mode_helper.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> index 488355b..e025639 100644
> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -142,6 +142,11 @@ static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
>                       sizeof(dp_dual_mode_hdmi_id)) == 0;
>  }
>
> +static bool is_type1_adaptor(uint8_t adaptor_id)
> +{
> +       return adaptor_id == 0 || adaptor_id == 0xff;
> +}
> +
>  static bool is_type2_adaptor(uint8_t adaptor_id)
>  {
>         return adaptor_id == (DP_DUAL_MODE_TYPE_TYPE2 |
> @@ -193,6 +198,8 @@ 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_HDMI_ID,
>                                     hdmi_id, sizeof(hdmi_id));
> +       DRM_DEBUG_KMS("DP dual mode HDMI ID: %*pE (err %zd)\n",
> +                     ret ? 0 : (int)sizeof(hdmi_id), hdmi_id, ret);
>         if (ret)
>                 return DRM_DP_DUAL_MODE_UNKNOWN;
>
> @@ -210,6 +217,8 @@ 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));
> +       DRM_DEBUG_KMS("DP dual mode adaptor ID: %02x (err %zd)\n",
> +                     adaptor_id, ret);
>         if (ret == 0) {
>                 if (is_lspcon_adaptor(hdmi_id, adaptor_id))
>                         return DRM_DP_DUAL_MODE_LSPCON;
> @@ -219,6 +228,15 @@ enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>                         else
>                                 return DRM_DP_DUAL_MODE_TYPE2_DVI;
>                 }
> +               /*
> +                * If neither a proper type 1 ID nor a broken type 1 adaptor
> +                * as described above, assume type 1, but let the user know
> +                * that we may have misdetected the type.
> +                */
> +               if (!is_type1_adaptor(adaptor_id) && adaptor_id != hdmi_id[0])
> +                       DRM_ERROR("Unexpected DP dual mode adaptor ID %02x\n",
> +                                 adaptor_id);
> +
>         }
>
>         if (is_hdmi_adaptor(hdmi_id))
> --
> 2.5.0
>
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