The function reads the link status (6 bytes starting at offset 0x202) from the DPCD so that it can be conveniently passed to other DPCD helpers.
Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/drm_dp_helper.c | 16 ++++++++++++++++ include/drm/drm_dp_helper.h | 3 +++ 2 files changed, 19 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index bd622d462ca7..8111b8e5a8bc 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -462,3 +462,19 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset, return -EIO; } EXPORT_SYMBOL(drm_dp_dpcd_write); + +/** + * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207) + * @aux: DisplayPort AUX channel + * @status: buffer to store the link status in (must be at least 6 bytes) + * + * Returns the number of bytes transferred on success or a negative error + * code on failure. + */ +int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, + u8 status[DP_LINK_STATUS_SIZE]) +{ + return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status, + DP_LINK_STATUS_SIZE); +} +EXPORT_SYMBOL(drm_dp_dpcd_read_link_status); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 0b14e799cd98..38cbaef05005 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -461,4 +461,7 @@ static inline ssize_t drm_dp_dpcd_writeb(struct drm_dp_aux *aux, u8 value, return drm_dp_dpcd_write(aux, offset, &value, 1); }
+int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux, + u8 status[DP_LINK_STATUS_SIZE]); + #endif /* _DRM_DP_HELPER_H_ */