[RFC 6/7] drm/dp_helper: Add support for link status and link recovery

[Ankit Nautiyal]

From: Swati Sharma <swati2.sharma at intel.com>

This patch adds support for link status and link recovery. There
are specific DPCD’s defined for link status check and recovery in
case of any issues. PCON will communicate the same using an IRQ_HPD
to source. HDMI sink would have indicated the same to PCON using
SCDC interrupt mechanism. While source can always read final HDMI
sink’s status using I2C over AUX, it’s easier and faster to read
the PCON’s already read HDMI sink’s status registers.

Signed-off-by: Swati Sharma <swati2.sharma at intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 33 +++++++++++++++++++++++++++++++++
 include/drm/drm_dp_helper.h     | 16 ++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 36302d4924f4..aac282bc5dfc 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -2671,3 +2671,36 @@ int drm_dp_pcon_hdmi_link_mode(struct drm_dp_aux *aux, u8 *frl_trained_mask)
 	return mode;
 }
 EXPORT_SYMBOL(drm_dp_pcon_hdmi_link_mode);
+
+void drm_dp_pcon_hdmi_frl_link_error_count(struct drm_dp_aux *aux,
+					   struct drm_connector *connector)
+{
+	u8 buf, error_count;
+	int i, num_error;
+	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+
+	for (i = 0; i < hdmi->max_lane; i++)
+	{
+		if (drm_dp_dpcd_readb(aux, DP_PCON_HDMI_ERROR_STATUS_LN0 + i , &buf) < 0)
+			return;
+
+		error_count = buf & DP_PCON_HDMI_ERROR_COUNT_MASK;
+
+	switch(error_count) {
+	case DP_PCON_HDMI_ERROR_COUNT_HUNDRED_PLUS:
+		num_error = 100;
+		break;
+	case DP_PCON_HDMI_ERROR_COUNT_TEN_PLUS:
+		num_error = 10;
+		break;
+	case DP_PCON_HDMI_ERROR_COUNT_THREE_PLUS:
+		num_error = 3;
+		break;
+	default:
+		num_error = 0;
+	}
+
+		DRM_ERROR("More than %d errors since the last read for lane %d", num_error, i);
+	}
+}
+EXPORT_SYMBOL(drm_dp_pcon_hdmi_frl_link_error_count);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 58a6600e5698..7b143a2ae5ff 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -946,6 +946,11 @@ struct drm_device;
 # define DP_CEC_IRQ                          (1 << 2)
 
 #define DP_LINK_SERVICE_IRQ_VECTOR_ESI0     0x2005   /* 1.2 */
+# define RX_CAP_CHANGED                      (1 << 0)
+# define LINK_STATUS_CHANGED                 (1 << 1)
+# define STREAM_STATUS_CHANGED               (1 << 2)
+# define HDMI_LINK_STATUS_CHANGED            (1 << 3)
+# define CONNECTED_OFF_ENTRY_REQUESTED       (1 << 4)
 
 #define DP_PSR_ERROR_STATUS                 0x2006  /* XXX 1.2? */
 # define DP_PSR_LINK_CRC_ERROR              (1 << 0)
@@ -1130,6 +1135,16 @@ struct drm_device;
 #define DP_PROTOCOL_CONVERTER_CONTROL_2		0x3052 /* DP 1.3 */
 # define DP_CONVERSION_TO_YCBCR422_ENABLE	(1 << 0) /* DP 1.3 */
 
+/* PCON Downstream HDMI ERROR Status per Lane */
+#define DP_PCON_HDMI_ERROR_STATUS_LN0          0x3037
+#define DP_PCON_HDMI_ERROR_STATUS_LN1          0x3038
+#define DP_PCON_HDMI_ERROR_STATUS_LN2          0x3039
+#define DP_PCON_HDMI_ERROR_STATUS_LN3          0x303A
+# define DP_PCON_HDMI_ERROR_COUNT_MASK         (0x7 << 0)
+# define DP_PCON_HDMI_ERROR_COUNT_THREE_PLUS   (1 << 0)
+# define DP_PCON_HDMI_ERROR_COUNT_TEN_PLUS     (1 << 1)
+# define DP_PCON_HDMI_ERROR_COUNT_HUNDRED_PLUS (1 << 2)
+
 /* HDCP 1.3 and HDCP 2.2 */
 #define DP_AUX_HDCP_BKSV		0x68000
 #define DP_AUX_HDCP_RI_PRIME		0x68005
@@ -1985,4 +2000,5 @@ int drm_dp_pcon_frl_enable(struct drm_dp_aux *aux);
 
 bool drm_dp_pcon_hdmi_link_active(struct drm_dp_aux *aux);
 int drm_dp_pcon_hdmi_link_mode(struct drm_dp_aux *aux, u8 *frl_trained_mask);
+void drm_dp_pcon_hdmi_frl_link_error_count(struct drm_dp_aux *aux, struct drm_connector *connector);
 #endif /* _DRM_DP_HELPER_H_ */
-- 
2.17.1