drm: Add DP branch device info on debugfs

Read DisplayPort branch device info from through debugfs
interface.

v2: use drm_dp_helper routines to collect data
v3: cleanup to match the drm_dp_helper.c patches introduced
    earlier in this series
v4: move DP branch device info to function 'intel_dp_branch_device_info()'
v5: initial step to move debugging info from intel_dp. to drm_dp_helper.c (Daniel)
v6: read hw and sw revision without using specific drm_dp_helper routines
v7: indentation fixes (Jim Bride)

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Jim Bride <jim.bride@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1473419458-17080-12-git-send-email-mika.kahola@intel.com

2 files changed, 88 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 7b3a638725d9..e26936309e07 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -525,6 +525,91 @@ int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6])
 }
 EXPORT_SYMBOL(drm_dp_downstream_id);
 
+/**
+ * drm_dp_downstream_debug() - debug DP branch devices
+ * @m: pointer for debugfs file
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ * @aux: DisplayPort AUX channel
+ *
+ */
+void drm_dp_downstream_debug(struct seq_file *m,
+			     const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+			     const u8 port_cap[4], struct drm_dp_aux *aux)
+{
+	bool detailed_cap_info = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+				 DP_DETAILED_CAP_INFO_AVAILABLE;
+	int clk;
+	int bpc;
+	char id[6];
+	int len;
+	uint8_t rev[2];
+	int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
+	bool branch_device = dpcd[DP_DOWNSTREAMPORT_PRESENT] &
+			     DP_DWN_STRM_PORT_PRESENT;
+
+	seq_printf(m, "\tDP branch device present: %s\n",
+		   branch_device ? "yes" : "no");
+
+	if (!branch_device)
+		return;
+
+	switch (type) {
+	case DP_DS_PORT_TYPE_DP:
+		seq_puts(m, "\t\tType: DisplayPort\n");
+		break;
+	case DP_DS_PORT_TYPE_VGA:
+		seq_puts(m, "\t\tType: VGA\n");
+		break;
+	case DP_DS_PORT_TYPE_DVI:
+		seq_puts(m, "\t\tType: DVI\n");
+		break;
+	case DP_DS_PORT_TYPE_HDMI:
+		seq_puts(m, "\t\tType: HDMI\n");
+		break;
+	case DP_DS_PORT_TYPE_NON_EDID:
+		seq_puts(m, "\t\tType: others without EDID support\n");
+		break;
+	case DP_DS_PORT_TYPE_DP_DUALMODE:
+		seq_puts(m, "\t\tType: DP++\n");
+		break;
+	case DP_DS_PORT_TYPE_WIRELESS:
+		seq_puts(m, "\t\tType: Wireless\n");
+		break;
+	default:
+		seq_puts(m, "\t\tType: N/A\n");
+	}
+
+	drm_dp_downstream_id(aux, id);
+	seq_printf(m, "\t\tID: %s\n", id);
+
+	len = drm_dp_dpcd_read(aux, DP_BRANCH_HW_REV, &rev[0], 1);
+	if (len > 0)
+		seq_printf(m, "\t\tHW: %d.%d\n",
+			   (rev[0] & 0xf0) >> 4, rev[0] & 0xf);
+
+	len = drm_dp_dpcd_read(aux, DP_BRANCH_SW_REV, &rev, 2);
+	if (len > 0)
+		seq_printf(m, "\t\tSW: %d.%d\n", rev[0], rev[1]);
+
+	if (detailed_cap_info) {
+		clk = drm_dp_downstream_max_clock(dpcd, port_cap);
+
+		if (clk > 0) {
+			if (type == DP_DS_PORT_TYPE_VGA)
+				seq_printf(m, "\t\tMax dot clock: %d kHz\n", clk);
+			else
+				seq_printf(m, "\t\tMax TMDS clock: %d kHz\n", clk);
+		}
+
+		bpc = drm_dp_downstream_max_bpc(dpcd, port_cap);
+
+		if (bpc > 0)
+			seq_printf(m, "\t\tMax bpc: %d\n", bpc);
+	}
+}
+EXPORT_SYMBOL(drm_dp_downstream_debug);
+
 /*
  * I2C-over-AUX implementation
  */
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 6a270bc0fdb3..a6d174ac6652 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2860,6 +2860,9 @@ static void intel_dp_info(struct seq_file *m,
 	seq_printf(m, "\taudio support: %s\n", yesno(intel_dp->has_audio));
 	if (intel_connector->base.connector_type == DRM_MODE_CONNECTOR_eDP)
 		intel_panel_info(m, &intel_connector->panel);
+
+	drm_dp_downstream_debug(m, intel_dp->dpcd, intel_dp->downstream_ports,
+				&intel_dp->aux);
 }
 
 static void intel_hdmi_info(struct seq_file *m,