[PATCH 6.6 365/567] drm/bridge: ti-sn65dsi86: Add support for DisplayPort mode with HPD

Greg Kroah-Hartman
2026-03-23T15:10:25Z

6.6-stable review patch. If anyone has any objections, please let me know.

------------------

From: John Ripple <john.ripple@keysight.com>

commit 9133bc3f0564890218cbba6cc7e81ebc0841a6f1 upstream.

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>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20250915174543.2564994-1-john.ripple@keysight.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/bridge/ti-sn65dsi86.c | 112 ++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)

--- 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_sn6
.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)
{
@@ -362,6 +394,7 @@ static void ti_sn65dsi86_disable_comms(s
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);
@@ -396,6 +429,13 @@ static int __maybe_unused ti_sn65dsi86_r
if (pdata->refclk)
ti_sn65dsi86_enable_comms(pdata);

+ 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;
}

@@ -1223,6 +1263,8 @@ static void ti_sn65dsi86_debugfs_init(st
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
@@ -1231,11 +1273,35 @@ static void ti_sn_bridge_hpd_enable(stru
*/

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);
}
@@ -1321,6 +1387,41 @@ static int ti_sn_bridge_parse_dsi_host(s
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)
{
@@ -1951,6 +2052,7 @@ static int ti_sn65dsi86_probe(struct i2c
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,
@@ -1981,6 +2083,16 @@ static int ti_sn65dsi86_probe(struct i2c
if (ret)
return ret;

+ 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