[PATCH v2 10/21] drm/dp: Read alternate scrambler reset capability from sink

[Thierry Reding <thierry.reding@xxxxxxxxx>]

From: Thierry Reding <treding@xxxxxxxxxx>

Parse from the sink capabilities whether or not the eDP alternate
scrambler reset value of 0xfffe is supported.

Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
 drivers/gpu/drm/drm_dp_helper.c | 5 +++++
 include/drm/drm_dp_helper.h     | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 1c238196c8b4..acab8dc48e2c 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -358,6 +358,7 @@ static void drm_dp_link_caps_reset(struct drm_dp_link_caps *caps)
 	caps->tps3_supported = false;
 	caps->fast_training = false;
 	caps->channel_coding = false;
+	caps->alternate_scrambler_reset = false;
 }
 
 void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest,
@@ -367,6 +368,7 @@ void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest,
 	dest->tps3_supported = src->tps3_supported;
 	dest->fast_training = src->fast_training;
 	dest->channel_coding = src->channel_coding;
+	dest->alternate_scrambler_reset = src->alternate_scrambler_reset;
 }
 EXPORT_SYMBOL(drm_dp_link_caps_copy);
 
@@ -416,6 +418,9 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
 	link->caps.fast_training = drm_dp_fast_training_cap(values);
 	link->caps.channel_coding = drm_dp_channel_coding_supported(values);
 
+	if (drm_dp_alternate_scrambler_reset_cap(values))
+		link->caps.alternate_scrambler_reset = true;
+
 	link->rate = link->max_rate;
 	link->lanes = link->max_lanes;
 
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index d144d3a54dbc..f9f65bc13df5 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1222,6 +1222,13 @@ drm_dp_channel_coding_supported(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
 	return dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_8B10B;
 }
 
+static inline bool
+drm_dp_alternate_scrambler_reset_cap(const u8 dpcd[DP_RECEIVER_CAP_SIZE])
+{
+	return dpcd[DP_EDP_CONFIGURATION_CAP] &
+			DP_ALTERNATE_SCRAMBLER_RESET_CAP;
+}
+
 /*
  * DisplayPort AUX channel
  */
@@ -1379,12 +1386,14 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
  * @tps3_supported: training pattern sequence 3 supported for equalization
  * @fast_training: AUX CH handshake not required for link training
  * @channel_coding: ANSI 8B/10B channel coding capability
+ * @alternate_scrambler_reset: eDP alternate scrambler reset capability
  */
 struct drm_dp_link_caps {
 	bool enhanced_framing;
 	bool tps3_supported;
 	bool fast_training;
 	bool channel_coding;
+	bool alternate_scrambler_reset;
 };
 
 void drm_dp_link_caps_copy(struct drm_dp_link_caps *dest,
-- 
2.22.0

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