diff mbox series

[v6,4/4] drm: bridge: ti-sn65dsi83: Add error recovery mechanism

Message ID 20250210132620.42263-5-herve.codina@bootlin.com (mailing list archive)
State New, archived
Headers show
Series Add support for errors recovery in the TI SN65DSI83 bridge driver | expand

Commit Message

Herve Codina Feb. 10, 2025, 1:26 p.m. UTC 
In some cases observed during ESD tests, the TI SN65DSI83 cannot recover
from errors by itself. A full restart of the bridge is needed in those
cases to have the bridge output LVDS signals again.

Also, during tests, cases were observed where reading the status of the
bridge was not even possible. Indeed, in those cases, the bridge stops
to acknowledge I2C transactions. Only a full reset of the bridge (power
off/on) brings back the bridge to a functional state.

The TI SN65DSI83 has some error detection capabilities. Introduce an
error recovery mechanism based on this detection.

The errors detected are signaled through an interrupt. On system where
this interrupt is not available, the driver uses a polling monitoring
fallback to check for errors. When an error is present or when reading
the bridge status leads to an I2C failure, the recovery process is
launched.

Restarting the bridge needs to redo the initialization sequence. This
initialization sequence has to be done with the DSI data lanes driven in
LP11 state. In order to do that, the recovery process resets the whole
output path (i.e the path from the encoder to the connector) where the
bridge is located.

Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 142 ++++++++++++++++++++++++++
 1 file changed, 142 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 336380114eea..d84a03c79773 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -35,9 +35,12 @@ 
 #include <linux/of_graph.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge.h>
+#include <drm/drm_drv.h> /* DRM_MODESET_LOCK_ALL_BEGIN() needs drm_drv_uses_atomic_modeset() */
 #include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
@@ -159,6 +162,9 @@  struct sn65dsi83 {
 	bool				lvds_dual_link_even_odd_swap;
 	int				lvds_vod_swing_conf[2];
 	int				lvds_term_conf[2];
+	int				irq;
+	struct delayed_work		monitor_work;
+	struct work_struct		reset_work;
 };
 
 static const struct regmap_range sn65dsi83_readable_ranges[] = {
@@ -363,6 +369,106 @@  static u8 sn65dsi83_get_dsi_div(struct sn65dsi83 *ctx)
 	return dsi_div - 1;
 }
 
+static int sn65dsi83_reset_pipe(struct sn65dsi83 *sn65dsi83)
+{
+	struct drm_device *dev = sn65dsi83->bridge.dev;
+	struct drm_modeset_acquire_ctx ctx;
+	int err;
+
+	/*
+	 * Reset active outputs of the related CRTC.
+	 *
+	 * This way, drm core will reconfigure each components in the CRTC
+	 * outputs path. In our case, this will force the previous component to
+	 * go back in LP11 mode and so allow the reconfiguration of SN65DSI83
+	 * bridge.
+	 *
+	 * Keep the lock during the whole operation to be atomic.
+	 */
+
+	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, err);
+
+	if (!sn65dsi83->bridge.encoder->crtc) {
+		/*
+		 * No CRTC attached -> No CRTC active outputs to reset
+		 * This can happen when the SN65DSI83 is reset. Simply do
+		 * nothing without returning any errors.
+		 */
+		err = 0;
+		goto end;
+	}
+
+	dev_warn(sn65dsi83->dev, "reset the pipe\n");
+
+	err = drm_atomic_helper_reset_crtc(sn65dsi83->bridge.encoder->crtc, &ctx);
+
+end:
+	DRM_MODESET_LOCK_ALL_END(dev, ctx, err);
+
+	return err;
+}
+
+static void sn65dsi83_reset_work(struct work_struct *ws)
+{
+	struct sn65dsi83 *ctx = container_of(ws, struct sn65dsi83, reset_work);
+	int ret;
+
+	/* Reset the pipe */
+	ret = sn65dsi83_reset_pipe(ctx);
+	if (ret) {
+		dev_err(ctx->dev, "reset pipe failed %pe\n", ERR_PTR(ret));
+		return;
+	}
+	if (ctx->irq)
+		enable_irq(ctx->irq);
+}
+
+static void sn65dsi83_handle_errors(struct sn65dsi83 *ctx)
+{
+	unsigned int irq_stat;
+	int ret;
+
+	/*
+	 * Schedule a reset in case of:
+	 *  - the bridge doesn't answer
+	 *  - the bridge signals an error
+	 */
+
+	ret = regmap_read(ctx->regmap, REG_IRQ_STAT, &irq_stat);
+	if (ret || irq_stat) {
+		/*
+		 * IRQ acknowledged is not always possible (the bridge can be in
+		 * a state where it doesn't answer anymore). To prevent an
+		 * interrupt storm, disable interrupt. The interrupt will be
+		 * after the reset.
+		 */
+		if (ctx->irq)
+			disable_irq_nosync(ctx->irq);
+
+		schedule_work(&ctx->reset_work);
+	}
+}
+
+static void sn65dsi83_monitor_work(struct work_struct *work)
+{
+	struct sn65dsi83 *ctx = container_of(to_delayed_work(work),
+					     struct sn65dsi83, monitor_work);
+
+	sn65dsi83_handle_errors(ctx);
+
+	schedule_delayed_work(&ctx->monitor_work, msecs_to_jiffies(1000));
+}
+
+static void sn65dsi83_monitor_start(struct sn65dsi83 *ctx)
+{
+	schedule_delayed_work(&ctx->monitor_work, msecs_to_jiffies(1000));
+}
+
+static void sn65dsi83_monitor_stop(struct sn65dsi83 *ctx)
+{
+	cancel_delayed_work_sync(&ctx->monitor_work);
+}
+
 static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
 					struct drm_bridge_state *old_bridge_state)
 {
@@ -549,6 +655,15 @@  static void sn65dsi83_atomic_enable(struct drm_bridge *bridge,
 	regmap_read(ctx->regmap, REG_IRQ_STAT, &pval);
 	if (pval)
 		dev_err(ctx->dev, "Unexpected link status 0x%02x\n", pval);
+
+	if (ctx->irq) {
+		/* Enable irq to detect errors */
+		regmap_write(ctx->regmap, REG_IRQ_GLOBAL, REG_IRQ_GLOBAL_IRQ_EN);
+		regmap_write(ctx->regmap, REG_IRQ_EN, 0xff);
+	} else {
+		/* Use the polling task */
+		sn65dsi83_monitor_start(ctx);
+	}
 }
 
 static void sn65dsi83_atomic_disable(struct drm_bridge *bridge,
@@ -557,6 +672,15 @@  static void sn65dsi83_atomic_disable(struct drm_bridge *bridge,
 	struct sn65dsi83 *ctx = bridge_to_sn65dsi83(bridge);
 	int ret;
 
+	if (ctx->irq) {
+		/* Disable irq */
+		regmap_write(ctx->regmap, REG_IRQ_EN, 0x0);
+		regmap_write(ctx->regmap, REG_IRQ_GLOBAL, 0x0);
+	} else {
+		/* Stop the polling task */
+		sn65dsi83_monitor_stop(ctx);
+	}
+
 	/* Put the chip in reset, pull EN line low, and assure 10ms reset low timing. */
 	gpiod_set_value_cansleep(ctx->enable_gpio, 0);
 	usleep_range(10000, 11000);
@@ -806,6 +930,14 @@  static int sn65dsi83_host_attach(struct sn65dsi83 *ctx)
 	return 0;
 }
 
+static irqreturn_t sn65dsi83_irq(int irq, void *data)
+{
+	struct sn65dsi83 *ctx = data;
+
+	sn65dsi83_handle_errors(ctx);
+	return IRQ_HANDLED;
+}
+
 static int sn65dsi83_probe(struct i2c_client *client)
 {
 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
@@ -819,6 +951,8 @@  static int sn65dsi83_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	ctx->dev = dev;
+	INIT_WORK(&ctx->reset_work, sn65dsi83_reset_work);
+	INIT_DELAYED_WORK(&ctx->monitor_work, sn65dsi83_monitor_work);
 
 	if (dev->of_node) {
 		model = (enum sn65dsi83_model)(uintptr_t)
@@ -843,6 +977,14 @@  static int sn65dsi83_probe(struct i2c_client *client)
 	if (IS_ERR(ctx->regmap))
 		return dev_err_probe(dev, PTR_ERR(ctx->regmap), "failed to get regmap\n");
 
+	if (client->irq) {
+		ctx->irq = client->irq;
+		ret = devm_request_threaded_irq(ctx->dev, ctx->irq, NULL, sn65dsi83_irq,
+						IRQF_ONESHOT, dev_name(ctx->dev), ctx);
+		if (ret)
+			return dev_err_probe(dev, ret, "failed to request irq\n");
+	}
+
 	dev_set_drvdata(dev, ctx);
 	i2c_set_clientdata(client, ctx);