From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
The downstream facing port caps in the DPCD can give us a hint
as to what kind of display mode the sink can use if it doesn't
have an EDID. Use that information to pick a suitable mode.
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 54 +++++++++++++++++++++++++++++++++
drivers/gpu/drm/drm_edid.c | 21 +++++++++++++
include/drm/drm_dp_helper.h | 12 ++++++++
include/drm/drm_edid.h | 4 +++
4 files changed, 91 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 31ca550467ed..507282dc79ac 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -615,6 +615,60 @@ int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
}
EXPORT_SYMBOL(drm_dp_downstream_max_bpc);
+/**
+ * drm_dp_downstream_mode() - return a mode for downstream facing port
+ * @dpcd: DisplayPort configuration data
+ * @port_cap: port capabilities
+ *
+ * Provides a suitable mode for downstream facing ports without EDID.
+ *
+ * Returns a new drm_display_mode on success or NULL on failure
+ */
+struct drm_display_mode *
+drm_dp_downstream_mode(struct drm_device *dev,
+ const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4])
+
+{
+ u8 vic;
+
+ if (!drm_dp_is_branch(dpcd))
+ return NULL;
+
+ if (dpcd[DP_DPCD_REV] < 0x11)
+ return NULL;
+
+ switch (port_cap[0] & DP_DS_PORT_TYPE_MASK) {
+ case DP_DS_PORT_TYPE_NON_EDID:
+ switch (port_cap[0] & DP_DS_NON_EDID_MASK) {
+ case DP_DS_NON_EDID_720x480i_60:
+ vic = 6;
+ break;
+ case DP_DS_NON_EDID_720x480i_50:
+ vic = 21;
+ break;
+ case DP_DS_NON_EDID_1920x1080i_60:
+ vic = 5;
+ break;
+ case DP_DS_NON_EDID_1920x1080i_50:
+ vic = 20;
+ break;
+ case DP_DS_NON_EDID_1280x720_60:
+ vic = 4;
+ break;
+ case DP_DS_NON_EDID_1280x720_50:
+ vic = 19;
+ break;
+ default:
+ return NULL;
+ }
+ return drm_display_mode_from_cea_vic(dev, vic);
+ default:
+ return NULL;
+ }
+}
+EXPORT_SYMBOL(drm_dp_downstream_mode);
+
/**
* drm_dp_downstream_id() - identify branch device
* @aux: DisplayPort AUX channel
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 99769d6c9f84..4894a00b0711 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3633,6 +3633,27 @@ drm_add_cmdb_modes(struct drm_connector *connector, u8 svd)
bitmap_set(hdmi->y420_cmdb_modes, vic, 1);
}
+struct drm_display_mode *
+drm_display_mode_from_cea_vic(struct drm_device *dev,
+ u8 video_code)
+{
+ const struct drm_display_mode *cea_mode;
+ struct drm_display_mode *newmode;
+
+ cea_mode = cea_mode_for_vic(video_code);
+ if (!cea_mode)
+ return NULL;
+
+ newmode = drm_mode_duplicate(dev, cea_mode);
+ if (!newmode)
+ return NULL;
+
+ newmode->vrefresh = 0;
+
+ return newmode;
+}
+EXPORT_SYMBOL(drm_display_mode_from_cea_vic);
+
static int
do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
{
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 89683a3a9af1..be4a5ffe4252 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -27,6 +27,8 @@
#include <linux/i2c.h>
#include <linux/types.h>
+struct drm_device;
+
/*
* Unless otherwise noted, all values are from the DP 1.1a spec. Note that
* DP and DPCD versions are independent. Differences from 1.0 are not noted,
@@ -384,6 +386,13 @@
# define DP_DS_PORT_TYPE_DP_DUALMODE 5
# define DP_DS_PORT_TYPE_WIRELESS 6
# define DP_DS_PORT_HPD (1 << 3)
+# define DP_DS_NON_EDID_MASK (0xf << 4)
+# define DP_DS_NON_EDID_720x480i_60 (1 << 4)
+# define DP_DS_NON_EDID_720x480i_50 (2 << 4)
+# define DP_DS_NON_EDID_1920x1080i_60 (3 << 4)
+# define DP_DS_NON_EDID_1920x1080i_50 (4 << 4)
+# define DP_DS_NON_EDID_1280x720_60 (5 << 4)
+# define DP_DS_NON_EDID_1280x720_50 (7 << 4)
/* offset 1 for VGA is maximum megapixels per second / 8 */
/* offset 1 for DVI/HDMI is maximum TMDS clock in Mbps / 2.5 */
/* offset 2 for VGA/DVI/HDMI */
@@ -1491,6 +1500,9 @@ int drm_dp_downstream_min_tmds_clock(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
int drm_dp_downstream_max_bpc(const u8 dpcd[DP_RECEIVER_CAP_SIZE],
const u8 port_cap[4],
const struct edid *edid);
+struct drm_display_mode *drm_dp_downstream_mode(struct drm_device *dev,
+ const u8 dpcd[DP_RECEIVER_CAP_SIZE],
+ const u8 port_cap[4]);
int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
void drm_dp_downstream_debug(struct seq_file *m,
const u8 dpcd[DP_RECEIVER_CAP_SIZE],
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index f0b03d401c27..cb1be3f5840a 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -503,4 +503,8 @@ void drm_edid_get_monitor_name(struct edid *edid, char *name,
struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
int hsize, int vsize, int fresh,
bool rb);
+struct drm_display_mode *
+drm_display_mode_from_cea_vic(struct drm_device *dev,
+ u8 video_code);
+
#endif /* __DRM_EDID_H__ */
--
2.24.1
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