From: "Srivatsa, Anusha" <anusha.srivatsa@xxxxxxxxx>
DP 1.4 has Forward Error Correction Support(FEC).
Add helper function to check if the sink device
supports FEC.
v2: Separate the helper and the code that uses the helper into
two separate patches. (Manasi)
v3:
- Move the code to drm_dp_helper.c (Manasi)
- change the return type, code style changes (Gaurav)
- Use drm_dp_dpcd_readb instead of drm_dp_dpcd_read. (Jani)
Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 14 ++++++++++++++
include/drm/drm_dp_helper.h | 3 +++
2 files changed, 17 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 7dc61d1..2e127b9 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1425,3 +1425,17 @@ u8 drm_dp_dsc_sink_max_color_depth(const u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
return 0;
}
EXPORT_SYMBOL(drm_dp_dsc_sink_max_color_depth);
+
+/* Forward Error Correction support for DP 1.4 */
+int drm_dp_sink_supports_fec(struct drm_dp_aux *aux)
+{
+ int fec_err;
+ u8 fec_cap;
+
+ fec_err = drm_dp_dpcd_readb(aux, DP_FEC_CAPABILITY, &fec_cap);
+ if (fec_err < 0)
+ return fec_err;
+
+ return fec_cap & DP_FEC_CAPABLE;
+}
+EXPORT_SYMBOL(drm_dp_sink_supports_fec);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index f178933..d958c7d 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1270,6 +1270,9 @@ 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);
+/* Forward Error Correction Support on DP 1.4 */
+int drm_dp_sink_supports_fec(struct drm_dp_aux *aux);
+
struct drm_dp_dpcd_ident {
u8 oui[3];
u8 device_id[6];
--
2.7.4
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