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drm/dp: add drm_dp_link_power_down() helper

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We had _power_up(), but drivers also need to be able to power down.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Rob Clark 2014-12-02 10:43:07 -05:00
parent 9ec60ca682
commit d816f07736
2 changed files with 32 additions and 0 deletions
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31
drivers/gpu/drm/drm_dp_helper.c
View file

@ -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

1
include/drm/drm_dp_helper.h
View file

@ -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);