Add support for DisplayPort to the bridge, which entails the following:
- Get and use an interrupt for HPD;
- Properly clear all status bits in the interrupt handler;

Signed-off-by: John Ripple <john.ripple@keysight.com>
---
V1 -> V2: Cleaned up coding style and addressed review comments
V2 -> V3:
- Removed unused HPD IRQs
- Added mutex around HPD enable/disable and IRQ handler.
- Cleaned up error handling and variable declarations
- Only enable IRQs if the i2c client has an IRQ
- Moved IRQ_EN to ti_sn65dsi86_resume()
- Created ti_sn65dsi86_read_u8() helper function
V3 -> V4:
- Formatting
- Allow device tree to set interrupt type.
- Use hpd_mutex over less code.
V4 -> V5:
- Formatting.
- Symmetric mutex use in hpd enable/disable functions.
- Only set and clear specific bits for IRQ enable and disable.
- Better error handling in interrupt.
V5 -> V6:
- Formatting.
- Convert pr_ to dev_ for printing.
- Add error check to regmap_clear_bits() call.
V7:
- Move status check in interrupt.
---
 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 112 ++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index ae0d08e5e960..276d05d25ad8 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -106,10 +106,21 @@
 #define SN_PWM_EN_INV_REG			0xA5
 #define  SN_PWM_INV_MASK			BIT(0)
 #define  SN_PWM_EN_MASK				BIT(1)
+
+#define SN_IRQ_EN_REG				0xE0
+#define  IRQ_EN					BIT(0)
+
+#define SN_IRQ_EVENTS_EN_REG			0xE6
+#define  HPD_INSERTION_EN			BIT(1)
+#define  HPD_REMOVAL_EN				BIT(2)
+
 #define SN_AUX_CMD_STATUS_REG			0xF4
 #define  AUX_IRQ_STATUS_AUX_RPLY_TOUT		BIT(3)
 #define  AUX_IRQ_STATUS_AUX_SHORT		BIT(5)
 #define  AUX_IRQ_STATUS_NAT_I2C_FAIL		BIT(6)
+#define SN_IRQ_STATUS_REG			0xF5
+#define  HPD_REMOVAL_STATUS			BIT(2)
+#define  HPD_INSERTION_STATUS			BIT(1)
 
 #define MIN_DSI_CLK_FREQ_MHZ	40
 
@@ -152,7 +163,9 @@
  * @ln_assign:    Value to program to the LN_ASSIGN register.
  * @ln_polrs:     Value for the 4-bit LN_POLRS field of SN_ENH_FRAME_REG.
  * @comms_enabled: If true then communication over the aux channel is enabled.
+ * @hpd_enabled:   If true then HPD events are enabled.
  * @comms_mutex:   Protects modification of comms_enabled.
+ * @hpd_mutex:     Protects modification of hpd_enabled.
  *
  * @gchip:        If we expose our GPIOs, this is used.
  * @gchip_output: A cache of whether we've set GPIOs to output.  This
@@ -190,7 +203,9 @@ struct ti_sn65dsi86 {
 	u8				ln_assign;
 	u8				ln_polrs;
 	bool				comms_enabled;
+	bool				hpd_enabled;
 	struct mutex			comms_mutex;
+	struct mutex			hpd_mutex;
 
 #if defined(CONFIG_OF_GPIO)
 	struct gpio_chip		gchip;
@@ -221,6 +236,23 @@ static const struct regmap_config ti_sn65dsi86_regmap_config = {
 	.max_register = 0xFF,
 };
 
+static int ti_sn65dsi86_read_u8(struct ti_sn65dsi86 *pdata, unsigned int reg,
+				u8 *val)
+{
+	int ret;
+	unsigned int reg_val;
+
+	ret = regmap_read(pdata->regmap, reg, &reg_val);
+	if (ret) {
+		dev_err(pdata->dev, "fail to read raw reg %#x: %d\n",
+			reg, ret);
+		return ret;
+	}
+	*val = (u8)reg_val;
+
+	return 0;
+}
+
 static int __maybe_unused ti_sn65dsi86_read_u16(struct ti_sn65dsi86 *pdata,
 						unsigned int reg, u16 *val)
 {
@@ -379,6 +411,7 @@ static void ti_sn65dsi86_disable_comms(struct ti_sn65dsi86 *pdata)
 static int __maybe_unused ti_sn65dsi86_resume(struct device *dev)
 {
 	struct ti_sn65dsi86 *pdata = dev_get_drvdata(dev);
+	const struct i2c_client *client = to_i2c_client(pdata->dev);
 	int ret;
 
 	ret = regulator_bulk_enable(SN_REGULATOR_SUPPLY_NUM, pdata->supplies);
@@ -413,6 +446,13 @@ static int __maybe_unused ti_sn65dsi86_resume(struct device *dev)
 	if (pdata->refclk)
 		ti_sn65dsi86_enable_comms(pdata, NULL);
 
+	if (client->irq) {
+		ret = regmap_update_bits(pdata->regmap, SN_IRQ_EN_REG, IRQ_EN,
+					 IRQ_EN);
+		if (ret)
+			dev_err(pdata->dev, "Failed to enable IRQ events: %d\n", ret);
+	}
+
 	return ret;
 }
 
@@ -1211,6 +1251,8 @@ static void ti_sn65dsi86_debugfs_init(struct drm_bridge *bridge, struct dentry *
 static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
 {
 	struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
+	const struct i2c_client *client = to_i2c_client(pdata->dev);
+	int ret;
 
 	/*
 	 * Device needs to be powered on before reading the HPD state
@@ -1219,11 +1261,35 @@ static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
 	 */
 
 	pm_runtime_get_sync(pdata->dev);
+
+	mutex_lock(&pdata->hpd_mutex);
+	pdata->hpd_enabled = true;
+	mutex_unlock(&pdata->hpd_mutex);
+
+	if (client->irq) {
+		ret = regmap_set_bits(pdata->regmap, SN_IRQ_EVENTS_EN_REG,
+				      HPD_REMOVAL_EN | HPD_INSERTION_EN);
+		if (ret)
+			dev_err(pdata->dev, "Failed to enable HPD events: %d\n", ret);
+	}
 }
 
 static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
 {
 	struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
+	const struct i2c_client *client = to_i2c_client(pdata->dev);
+	int ret;
+
+	if (client->irq) {
+		ret = regmap_clear_bits(pdata->regmap, SN_IRQ_EVENTS_EN_REG,
+					HPD_REMOVAL_EN | HPD_INSERTION_EN);
+		if (ret)
+			dev_err(pdata->dev, "Failed to disable HPD events: %d\n", ret);
+	}
+
+	mutex_lock(&pdata->hpd_mutex);
+	pdata->hpd_enabled = false;
+	mutex_unlock(&pdata->hpd_mutex);
 
 	pm_runtime_put_autosuspend(pdata->dev);
 }
@@ -1309,6 +1375,41 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn65dsi86 *pdata)
 	return 0;
 }
 
+static irqreturn_t ti_sn_bridge_interrupt(int irq, void *private)
+{
+	struct ti_sn65dsi86 *pdata = private;
+	struct drm_device *dev = pdata->bridge.dev;
+	u8 status;
+	int ret;
+	bool hpd_event;
+
+	ret = ti_sn65dsi86_read_u8(pdata, SN_IRQ_STATUS_REG, &status);
+	if (ret) {
+		dev_err(pdata->dev, "Failed to read IRQ status: %d\n", ret);
+		return IRQ_NONE;
+	}
+
+	hpd_event = status & (HPD_REMOVAL_STATUS | HPD_INSERTION_STATUS);
+
+	dev_dbg(pdata->dev, "(SN_IRQ_STATUS_REG = %#x)\n", status);
+	if (!status)
+		return IRQ_NONE;
+
+	ret = regmap_write(pdata->regmap, SN_IRQ_STATUS_REG, status);
+	if (ret) {
+		dev_err(pdata->dev, "Failed to clear IRQ status: %d\n", ret);
+		return IRQ_NONE;
+	}
+
+	/* Only send the HPD event if we are bound with a device. */
+	mutex_lock(&pdata->hpd_mutex);
+	if (pdata->hpd_enabled && hpd_event)
+		drm_kms_helper_hotplug_event(dev);
+	mutex_unlock(&pdata->hpd_mutex);
+
+	return IRQ_HANDLED;
+}
+
 static int ti_sn_bridge_probe(struct auxiliary_device *adev,
 			      const struct auxiliary_device_id *id)
 {
@@ -1931,6 +2032,7 @@ static int ti_sn65dsi86_probe(struct i2c_client *client)
 	dev_set_drvdata(dev, pdata);
 	pdata->dev = dev;
 
+	mutex_init(&pdata->hpd_mutex);
 	mutex_init(&pdata->comms_mutex);
 
 	pdata->regmap = devm_regmap_init_i2c(client,
@@ -1971,6 +2073,16 @@ static int ti_sn65dsi86_probe(struct i2c_client *client)
 	if (strncmp(id_buf, "68ISD   ", ARRAY_SIZE(id_buf)))
 		return dev_err_probe(dev, -EOPNOTSUPP, "unsupported device id\n");
 
+	if (client->irq) {
+		ret = devm_request_threaded_irq(pdata->dev, client->irq, NULL,
+						ti_sn_bridge_interrupt,
+						IRQF_ONESHOT,
+						dev_name(pdata->dev), pdata);
+
+		if (ret)
+			return dev_err_probe(dev, ret, "failed to request interrupt\n");
+	}
+
 	/*
 	 * Break ourselves up into a collection of aux devices. The only real
 	 * motiviation here is to solve the chicken-and-egg problem of probe

Hi,

On Mon, Sep 15, 2025 at 10:46 AM John Ripple <john.ripple@keysight.com> wrote:
>
> Add support for DisplayPort to the bridge, which entails the following:
> - Get and use an interrupt for HPD;
> - Properly clear all status bits in the interrupt handler;
>
> Signed-off-by: John Ripple <john.ripple@keysight.com>
> ---
> V1 -> V2: Cleaned up coding style and addressed review comments
> V2 -> V3:
> - Removed unused HPD IRQs
> - Added mutex around HPD enable/disable and IRQ handler.
> - Cleaned up error handling and variable declarations
> - Only enable IRQs if the i2c client has an IRQ
> - Moved IRQ_EN to ti_sn65dsi86_resume()
> - Created ti_sn65dsi86_read_u8() helper function
> V3 -> V4:
> - Formatting
> - Allow device tree to set interrupt type.
> - Use hpd_mutex over less code.
> V4 -> V5:
> - Formatting.
> - Symmetric mutex use in hpd enable/disable functions.
> - Only set and clear specific bits for IRQ enable and disable.
> - Better error handling in interrupt.
> V5 -> V6:
> - Formatting.
> - Convert pr_ to dev_ for printing.
> - Add error check to regmap_clear_bits() call.
> V7:
> - Move status check in interrupt.
> ---
>  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 112 ++++++++++++++++++++++++++
>  1 file changed, 112 insertions(+)

Reviewed-by: Douglas Anderson <dianders@chromium.org>

I'll plan to apply to drm-misc-next next week unless anything else comes up.

-Doug

Hi,

On Mon, Sep 15, 2025 at 10:57 AM Doug Anderson <dianders@chromium.org> wrote:
>
> Hi,
>
> On Mon, Sep 15, 2025 at 10:46 AM John Ripple <john.ripple@keysight.com> wrote:
> >
> > Add support for DisplayPort to the bridge, which entails the following:
> > - Get and use an interrupt for HPD;
> > - Properly clear all status bits in the interrupt handler;
> >
> > Signed-off-by: John Ripple <john.ripple@keysight.com>
> > ---
> > V1 -> V2: Cleaned up coding style and addressed review comments
> > V2 -> V3:
> > - Removed unused HPD IRQs
> > - Added mutex around HPD enable/disable and IRQ handler.
> > - Cleaned up error handling and variable declarations
> > - Only enable IRQs if the i2c client has an IRQ
> > - Moved IRQ_EN to ti_sn65dsi86_resume()
> > - Created ti_sn65dsi86_read_u8() helper function
> > V3 -> V4:
> > - Formatting
> > - Allow device tree to set interrupt type.
> > - Use hpd_mutex over less code.
> > V4 -> V5:
> > - Formatting.
> > - Symmetric mutex use in hpd enable/disable functions.
> > - Only set and clear specific bits for IRQ enable and disable.
> > - Better error handling in interrupt.
> > V5 -> V6:
> > - Formatting.
> > - Convert pr_ to dev_ for printing.
> > - Add error check to regmap_clear_bits() call.
> > V7:
> > - Move status check in interrupt.
> > ---
> >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 112 ++++++++++++++++++++++++++
> >  1 file changed, 112 insertions(+)
>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
>
> I'll plan to apply to drm-misc-next next week unless anything else comes up.

Pushed to drm-misc-next:

[1/1] drm/bridge: ti-sn65dsi86: Add support for DisplayPort mode with HPD
      commit: 9133bc3f0564890218cbba6cc7e81ebc0841a6f1