[PATCH] drm/dp: add drm_dp_link_power_down() helper

[Alex Deucher]

On Tue, Dec 2, 2014 at 10:46 AM, Rob Clark <robdclark at gmail.com> wrote:
> We had _power_up(), but drivers also need to be able to power down.
>
> Signed-off-by: Rob Clark <robdclark at gmail.com>

Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

> ---
> This lets me drop edp_sink_power_state() from msm eDP code, and use
> the helpers instead.
>
>  drivers/gpu/drm/drm_dp_helper.c | 31 +++++++++++++++++++++++++++++++
>  include/drm/drm_dp_helper.h     |  1 +
>  2 files changed, 32 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 959e207..82122ec 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -353,6 +353,37 @@ int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
>  EXPORT_SYMBOL(drm_dp_link_power_up);
>
>  /**
> + * drm_dp_link_power_down() - power down a DisplayPort link
> + * @aux: DisplayPort AUX channel
> + * @link: pointer to a structure containing the link configuration
> + *
> + * Returns 0 on success or a negative error code on failure.
> + */
> +int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link)
> +{
> +       u8 value;
> +       int err;
> +
> +       /* DP_SET_POWER register is only available on DPCD v1.1 and later */
> +       if (link->revision < 0x11)
> +               return 0;
> +
> +       err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
> +       if (err < 0)
> +               return err;
> +
> +       value &= ~DP_SET_POWER_MASK;
> +       value |= DP_SET_POWER_D3;
> +
> +       err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
> +       if (err < 0)
> +               return err;
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_link_power_down);
> +
> +/**
>   * drm_dp_link_configure() - configure a DisplayPort link
>   * @aux: DisplayPort AUX channel
>   * @link: pointer to a structure containing the link configuration
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 11f8c84..7e25030 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -586,6 +586,7 @@ struct drm_dp_link {
>
>  int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
> +int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
>
>  int drm_dp_aux_register(struct drm_dp_aux *aux);
> --
> 1.9.3
>
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