[PATCH 2/3] drm/display/dp: Define function to setup Extended wake time

[Suraj Kandpal]

Extended wake timeout request helps to give additional
time by reading the DPCD register through which sink requests the
minimal amount of time required to wake the sink up.
Source  device shall keep retying the AUX tansaction till the
extended timeout that is being granted for LTTPRs from the
sink device.

Spec: DP v2.1 Section 3.6.12.3
Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c | 47 +++++++++++++++++++++++++
 include/drm/display/drm_dp_helper.h     |  1 +
 2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index da3c8521a7fa..9eae5ee85b13 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -459,6 +459,53 @@ void drm_dp_lttpr_link_train_channel_eq_delay(const struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_lttpr_link_train_channel_eq_delay);
 
+void drm_dp_lttpr_wake_timeout_setup(struct drm_dp_aux *aux, bool transparent_mode)
+{
+	u8 val = 1;
+	int ret;
+
+	if (transparent_mode) {
+		static const u8 timeout_mapping[] = {
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_1_MS] = 1,
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_20_MS] = 20,
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_40_MS] = 40,
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_60_MS] = 60,
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_80_MS] = 80,
+			[DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_100_MS] = 100,
+		};
+
+		ret = drm_dp_dpcd_readb(aux, DP_EXTENDED_DPRX_SLEEP_WAKE_TIMEOUT_REQUEST, &val);
+		if (ret != 1) {
+			drm_dbg_kms(aux->drm_dev,
+				    "Failed to read Extended sleep wake timeout request\n");
+			return;
+		}
+
+		val = (val < sizeof(timeout_mapping) && timeout_mapping[val]) ?
+			timeout_mapping[val] : 1;
+
+		if (val > 1)
+			drm_dp_dpcd_writeb(aux,
+					   DP_EXTENDED_DPRX_SLEEP_WAKE_TIMEOUT_GRANT,
+					   DP_DPRX_SLEEP_WAKE_TIMEOUT_PERIOD_GRANTED);
+	} else {
+		ret = drm_dp_dpcd_readb(aux, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT, &val);
+		if (ret != 1) {
+			drm_dbg_kms(aux->drm_dev,
+				    "Failed to read Extended sleep wake timeout request\n");
+			return;
+		}
+
+		val = (val & DP_EXTENDED_WAKE_TIMEOUT_REQUEST_MASK) ?
+			(val & DP_EXTENDED_WAKE_TIMEOUT_REQUEST_MASK) * 10 : 1;
+
+		if (val > 1)
+			drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT,
+					   DP_EXTENDED_WAKE_TIMEOUT_GRANT);
+	}
+}
+EXPORT_SYMBOL(drm_dp_lttpr_wake_timeout_setup);
+
 u8 drm_dp_link_rate_to_bw_code(int link_rate)
 {
 	switch (link_rate) {
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 8f4054a56039..89a34dff85a4 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -633,6 +633,7 @@ int drm_dp_lttpr_max_link_rate(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
 int drm_dp_lttpr_max_lane_count(const u8 caps[DP_LTTPR_COMMON_CAP_SIZE]);
 bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
 bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
+void drm_dp_lttpr_wake_timeout_setup(struct drm_dp_aux *aux, bool transparent_mode);
 
 void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
-- 
2.34.1