Helper routine to read out maximum supported bits per component for DisplayPort legay converters.
v2: Return early if detailed port cap info is not available. Replace if-else ladder with switch-case (Ville)
Reviewed-by: Jim Bride jim.bride@linux.intel.com Signed-off-by: Mika Kahola mika.kahola@intel.com --- drivers/gpu/drm/drm_dp_helper.c | 42 +++++++++++++++++++++++++++++++++++++++++ include/drm/drm_dp_helper.h | 2 ++ 2 files changed, 44 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index 7497490..14e8ea0 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -472,6 +472,48 @@ int drm_dp_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE], } EXPORT_SYMBOL(drm_dp_downstream_max_clock);
+/** + * drm_dp_downstream_max_bpc() - extract branch device max + * bits per component + * @dpcd: DisplayPort configuration data + * @port_cap: port capabilities + * + * Returns max bpc on success or 0 if max bpc not defined + */ +int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE], + const u8 port_cap[4]) +{ + int type = port_cap[0] & DP_DS_PORT_TYPE_MASK; + bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] & + DP_DETAILED_CAP_INFO_AVAILABLE; + int bpc; + + if (!detailed_cap_info) + return 0; + + switch (type) { + case DP_DS_PORT_TYPE_VGA: + case DP_DS_PORT_TYPE_DVI: + case DP_DS_PORT_TYPE_HDMI: + case DP_DS_PORT_TYPE_DP_DUALMODE: + bpc = port_cap[2] & DP_DS_MAX_BPC_MASK; + + switch (bpc) { + case DP_DS_8BPC: + return 8; + case DP_DS_10BPC: + return 10; + case DP_DS_12BPC: + return 12; + case DP_DS_16BPC: + return 16; + } + default: + return 0; + } +} +EXPORT_SYMBOL(drm_dp_downstream_max_bpc); + /* * I2C-over-AUX implementation */ diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 60dd9dc..f3d1424 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -817,6 +817,8 @@ 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_downstream_max_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE], const u8 port_cap[4]); +int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE], + const u8 port_cap[4]);
void drm_dp_aux_init(struct drm_dp_aux *aux); int drm_dp_aux_register(struct drm_dp_aux *aux);