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drm: rockchip: dw-dp: add AUX recovery for USB-C DP Alt Mode #494

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Merged
igorpecovnik merged 1 commit into from
Jun 5, 2026
+48 −3
Merged

drm: rockchip: dw-dp: add AUX recovery for USB-C DP Alt Mode #494

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51 changes: 48 additions & 3 deletions drivers/gpu/drm/rockchip/dw-dp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -507,6 +507,8 @@ struct dw_dp {
struct list_head mst_conn_list;
struct rockchip_dp_aux_client *aux_client;

struct edid *cached_edid;

struct drm_info_list *debugfs_files;
struct typec_mux_dev *mux;
};
Expand Down Expand Up @@ -1461,10 +1463,24 @@ static int dw_dp_connector_get_modes(struct drm_connector *connector)
if (!num_modes) {
edid = drm_bridge_get_edid(&dp->bridge, connector);
if (edid) {
kfree(dp->cached_edid);
dp->cached_edid = kmemdup(edid,
(edid->extensions + 1) * EDID_LENGTH,
GFP_KERNEL);
drm_connector_update_edid_property(connector, edid);
num_modes = drm_add_edid_modes(connector, edid);
dw_dp_update_hdr_property(connector);
kfree(edid);
} else if (dp->cached_edid) {
dev_warn(dp->dev, "EDID read failed, using cached EDID\n");
edid = kmemdup(dp->cached_edid,
(dp->cached_edid->extensions + 1) * EDID_LENGTH,
GFP_KERNEL);
if (edid) {
drm_connector_update_edid_property(connector, edid);
num_modes = drm_add_edid_modes(connector, edid);
kfree(edid);
}
}
}

Expand Down Expand Up @@ -3121,6 +3137,7 @@ static ssize_t dw_dp_aux_transfer(struct drm_dp_aux *aux,
unsigned long timeout = msecs_to_jiffies(10);
u32 status, value;
ssize_t ret = 0;
int retry;

if (WARN_ON(msg->size > 16))
return -E2BIG;
Expand Down Expand Up @@ -3150,11 +3167,37 @@ static ssize_t dw_dp_aux_transfer(struct drm_dp_aux *aux,
value = FIELD_PREP(I2C_ADDR_ONLY, 1);
value |= FIELD_PREP(AUX_CMD_TYPE, msg->request);
value |= FIELD_PREP(AUX_ADDR, msg->address);
regmap_write(dp->regmap, DPTX_AUX_CMD, value);
for (retry = 0; retry < 2; retry++) {
reinit_completion(&dp->complete);
regmap_write(dp->regmap, DPTX_AUX_CMD, value);

status = wait_for_completion_timeout(&dp->complete, timeout);
if (status)
break;

/* AUX timeout: reset AUX module and retry. On USB-C
* DP Alt Mode setups the AUX channel gets stuck after
* prolonged main link transmission. Reinitializing the
* completion and resetting the AUX module restores
* native AUX functionality for link training.
*/
if (retry == 0) {
dev_warn(dp->dev, "AUX timeout, resetting (cmd=0x%x addr=0x%x)\n",
msg->request, msg->address);
regmap_update_bits(dp->regmap, DPTX_SOFT_RESET_CTRL,
AUX_RESET, AUX_RESET);
usleep_range(10, 20);
regmap_update_bits(dp->regmap, DPTX_SOFT_RESET_CTRL,
AUX_RESET, 0);
usleep_range(100, 200);
dw_dp_aux_init(dp);
}
}

status = wait_for_completion_timeout(&dp->complete, timeout);
if (!status) {
dev_dbg(dp->dev, "timeout waiting for AUX reply\n");
regmap_read(dp->regmap, DPTX_AUX_STATUS, &value);
dev_info(dp->dev, "AUX timeout after recovery: cmd=0x%x addr=0x%x size=%d, AUX_STATUS=0x%x\n",
msg->request, msg->address, msg->size, value);
ret = -ETIMEDOUT;
goto out;
}
Expand Down Expand Up @@ -4544,6 +4587,8 @@ static enum drm_connector_status dw_dp_bridge_detect(struct drm_bridge *bridge)
return status;
}
if (status == connector_status_disconnected) {
kfree(dp->cached_edid);
dp->cached_edid = NULL;
if (dp->is_mst) {
dev_info(dp->dev, "MST device may have disappeared\n");
dp->is_mst = false;
Expand Down
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