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drm/bridge: dw-hdmi-qp: Add support for missing HPD

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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 rate limited debug message when we are
unable to complete an i2c read, as a disconnected device would
otherwise fill dmesg with i2c read errors.

Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patch.msgid.link/20251119225526.70588-3-macroalpha82@gmail.com
This commit is contained in:
Chris Morgan
2025-11-19 16:55:25 -06:00
committed by Heiko Stuebner
parent db04f0d47d
commit bafb6863dd
1 changed files with 30 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
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@@ -165,6 +165,7 @@ 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,
@@ -555,14 +556,22 @@ 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_ratelimited(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_ratelimited(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;
}
@@ -900,6 +909,15 @@ 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);
}
@@ -925,6 +943,11 @@ dw_hdmi_qp_bridge_tmds_char_rate_valid(const struct drm_bridge *bridge,
{
struct dw_hdmi_qp *hdmi = bridge->driver_private;
/*
* TODO: when hdmi->no_hpd is 1 we must not support modes that
* require scrambling, including every mode with a clock above
* HDMI14_MAX_TMDSCLK.
*/
if (rate > HDMI14_MAX_TMDSCLK) {
dev_dbg(hdmi->dev, "Unsupported TMDS char rate: %lld\n", rate);
return MODE_CLOCK_HIGH;
@@ -1277,12 +1300,15 @@ struct dw_hdmi_qp *dw_hdmi_qp_bind(struct platform_device *pdev,
if (ret)
return ERR_PTR(ret);
hdmi->no_hpd = device_property_read_bool(dev, "no-hpd");
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";