diff options
| -rw-r--r-- | drivers/gpu/drm/drm_dp_helper.c | 35 | ||||
| -rw-r--r-- | include/drm/drm_dp_helper.h | 19 |
2 files changed, 54 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 3e5f52110ea1..52e0ca9a5bb1 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -1208,3 +1208,38 @@ int drm_dp_stop_crc(struct drm_dp_aux *aux) return 0; } EXPORT_SYMBOL(drm_dp_stop_crc); + +/** + * drm_dp_read_desc - read sink/branch descriptor from DPCD + * @aux: DisplayPort AUX channel + * @desc: Device decriptor to fill from DPCD + * @is_branch: true for branch devices, false for sink devices + * + * Read DPCD 0x400 (sink) or 0x500 (branch) into @desc. Also debug log the + * identification. + * + * Returns 0 on success or a negative error code on failure. + */ +int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc, + bool is_branch) +{ + struct drm_dp_dpcd_ident *ident = &desc->ident; + unsigned int offset = is_branch ? DP_BRANCH_OUI : DP_SINK_OUI; + int ret, dev_id_len; + + ret = drm_dp_dpcd_read(aux, offset, ident, sizeof(*ident)); + if (ret < 0) + return ret; + + dev_id_len = strnlen(ident->device_id, sizeof(ident->device_id)); + + DRM_DEBUG_KMS("DP %s: OUI %*phD dev-ID %*pE HW-rev %d.%d SW-rev %d.%d\n", + is_branch ? "branch" : "sink", + (int)sizeof(ident->oui), ident->oui, + dev_id_len, ident->device_id, + ident->hw_rev >> 4, ident->hw_rev & 0xf, + ident->sw_major_rev, ident->sw_minor_rev); + + return 0; +} +EXPORT_SYMBOL(drm_dp_read_desc); diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index c0bd0d7651a9..84502da177a1 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -913,4 +913,23 @@ void drm_dp_aux_unregister(struct drm_dp_aux *aux); int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc); int drm_dp_stop_crc(struct drm_dp_aux *aux); +struct drm_dp_dpcd_ident { + u8 oui[3]; + u8 device_id[6]; + u8 hw_rev; + u8 sw_major_rev; + u8 sw_minor_rev; +} __packed; + +/** + * struct drm_dp_desc - DP branch/sink device descriptor + * @ident: DP device identification from DPCD 0x400 (sink) or 0x500 (branch). + */ +struct drm_dp_desc { + struct drm_dp_dpcd_ident ident; +}; + +int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc, + bool is_branch); + #endif /* _DRM_DP_HELPER_H_ */ |