From: Chris Morgan <[email protected]>

Add support for the dw-hdmi-qp driver to handle devices with missing
HPD pins.

Since in this situation we are now polling for the EDID data via i2c
change the error message to a debug message when we are unable to
complete an i2c read, as a disconnected device would otherwise fill
dmesg with i2c read errors.

Signed-off-by: Chris Morgan <[email protected]>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 35 +++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c 
b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index 39332c57f2c5..b221f797de3d 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@ -145,6 +145,7 @@ struct dw_hdmi_qp {
        struct regmap *regm;
 
        unsigned long tmds_char_rate;
+       bool no_hpd;
 };
 
 static void dw_hdmi_qp_write(struct dw_hdmi_qp *hdmi, unsigned int val,
@@ -520,6 +521,11 @@ static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
                i2c->is_regaddr = true;
        }
 
+       /*
+        * Mark errors as debug messages when using no_hpd so no device
+        * attached does not fill up dmesg.
+        */
+
        while (length--) {
                reinit_completion(&i2c->cmp);
 
@@ -535,14 +541,20 @@ static int dw_hdmi_qp_i2c_read(struct dw_hdmi_qp *hdmi,
 
                stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10);
                if (!stat) {
-                       dev_err(hdmi->dev, "i2c read timed out\n");
+                       if (hdmi->no_hpd)
+                               dev_dbg(hdmi->dev, "i2c read timed out\n");
+                       else
+                               dev_err(hdmi->dev, "i2c read timed out\n");
                        dw_hdmi_qp_write(hdmi, 0x01, I2CM_CONTROL0);
                        return -EAGAIN;
                }
 
                /* Check for error condition on the bus */
                if (i2c->stat & I2CM_NACK_RCVD_IRQ) {
-                       dev_err(hdmi->dev, "i2c read error\n");
+                       if (hdmi->no_hpd)
+                               dev_dbg(hdmi->dev, "i2c read error\n");
+                       else
+                               dev_err(hdmi->dev, "i2c read error\n");
                        dw_hdmi_qp_write(hdmi, 0x01, I2CM_CONTROL0);
                        return -EIO;
                }
@@ -879,6 +891,15 @@ static enum drm_connector_status
 dw_hdmi_qp_bridge_detect(struct drm_bridge *bridge, struct drm_connector 
*connector)
 {
        struct dw_hdmi_qp *hdmi = bridge->driver_private;
+       const struct drm_edid *drm_edid;
+
+       if (hdmi->no_hpd) {
+               drm_edid = drm_edid_read_ddc(connector, bridge->ddc);
+               if (drm_edid)
+                       return connector_status_connected;
+               else
+                       return connector_status_disconnected;
+       }
 
        return hdmi->phy.ops->read_hpd(hdmi, hdmi->phy.data);
 }
@@ -1074,12 +1095,18 @@ struct dw_hdmi_qp *dw_hdmi_qp_bind(struct 
platform_device *pdev,
        if (ret)
                return ERR_PTR(ret);
 
+       if (of_property_present(pdev->dev.of_node, "no-hpd"))
+               hdmi->no_hpd = 1;
+       else
+               hdmi->no_hpd = 0;
+
        hdmi->bridge.driver_private = hdmi;
        hdmi->bridge.ops = DRM_BRIDGE_OP_DETECT |
                           DRM_BRIDGE_OP_EDID |
                           DRM_BRIDGE_OP_HDMI |
-                          DRM_BRIDGE_OP_HDMI_AUDIO |
-                          DRM_BRIDGE_OP_HPD;
+                          DRM_BRIDGE_OP_HDMI_AUDIO;
+       if (!hdmi->no_hpd)
+               hdmi->bridge.ops |= DRM_BRIDGE_OP_HPD;
        hdmi->bridge.of_node = pdev->dev.of_node;
        hdmi->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
        hdmi->bridge.vendor = "Synopsys";
-- 
2.43.0

Reply via email to