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-rw-r--r--drivers/gpu/drm/drm_dp_helper.c31
-rw-r--r--include/drm/drm_dp_helper.h1
2 files changed, 32 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 79968e3..f128387 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -354,6 +354,37 @@ 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);
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