On 10/19/26 1:25 PM, Dmitry Baryshkov wrote:
> LCD panels on boards with PMI632, PM6150L or PM8150L take their bias
> rails from the LCDB block. Without a driver they only work as long as
> the bootloader has enabled it and nothing turns it off.
[...]
> +static bool qcom_lcdb_handle_sc(struct qcom_lcdb *lcdb)
> +{
> + guard(mutex)(&lcdb->lock);
> +
> + if (!lcdb->enabled_mask || lcdb->sc_disabled)
> + return false;
> +
> + qcom_lcdb_module_disable(lcdb);
> +
> + if (ktime_us_delta(ktime_get(), lcdb->sc_time) >
> LCDB_SC_RESET_CNT_DLY_US) {
> + lcdb->sc_count = 0;
> + } else if (lcdb->sc_count > LCDB_SC_CNT_MAX) {
> + dev_err(lcdb->dev, "persistent short circuit, keeping the
> outputs off\n");
> + lcdb->sc_disabled = true;
> + return true;
> + }
> +
> + lcdb->sc_count++;
> + lcdb->sc_time = ktime_get();
GPT:
The commit message says to restart up to ten times within one second,
but sc_time is updated on every fault.
Konrad
> +
> + if (qcom_lcdb_module_enable(lcdb)) {
> + dev_err(lcdb->dev, "failed to recover from a short circuit\n");
> + lcdb->sc_disabled = true;
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static irqreturn_t qcom_lcdb_sc_irq(int irq, void *data)
> +{
> + struct qcom_lcdb *lcdb = data;
> + unsigned int val;
> + int ret, i;
> +
> + ret = regmap_read(lcdb->regmap, lcdb->base + LCDB_INT_RT_STS, &val);
> + if (ret || !(val & LCDB_SC_ERROR_RT_STS))
> + return IRQ_HANDLED;
> +
> + /* Blanking time, a real short circuit is still reported afterwards */
> + usleep_range(2000, 2100);
> +
> + ret = regmap_read(lcdb->regmap, lcdb->base + LCDB_INT_RT_STS, &val);
> + if (ret || !(val & LCDB_SC_ERROR_RT_STS))
> + return IRQ_HANDLED;
> +
> + if (qcom_lcdb_handle_sc(lcdb)) {
> + for (i = 0; i < LCDB_NUM_RAILS; i++)
> + regulator_notifier_call_chain(lcdb->rdev[i],
> + REGULATOR_EVENT_FAIL,
> NULL);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int qcom_lcdb_hw_init(struct qcom_lcdb *lcdb)
> +{
> + unsigned int val;
> + int ret, i;
> +
> + for (i = 0; i < LCDB_NUM_RAILS; i++) {
> + ret = regmap_read(lcdb->regmap, lcdb->base + qcom_lcdb_vreg[i],
> &val);
> + if (ret)
> + return ret;
> +
> + lcdb->uV[i] = qcom_lcdb_sel_to_uV(val &
> LCDB_OUTPUT_VOLTAGE_MASK);
> + }
> +
> + ret = regmap_read(lcdb->regmap, lcdb->base + LCDB_ENABLE_CTL1, &val);
> + if (ret)
> + return ret;
> +
> + if (val & LCDB_MODULE_EN) {
> + lcdb->enabled_mask = GENMASK(LCDB_NUM_RAILS - 1, 0);
> + return 0;
> + }
> +
> + return regmap_set_bits(lcdb->regmap, lcdb->base + LCDB_MODULE_RDY,
> + LCDB_MODULE_RDY_BIT);
> +}
> +
> +static int qcom_lcdb_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct regulator_config cfg = {};
> + struct qcom_lcdb *lcdb;
> + int irq, ret, i;
> +
> + lcdb = devm_kzalloc(dev, sizeof(*lcdb), GFP_KERNEL);
> + if (!lcdb)
> + return -ENOMEM;
> +
> + lcdb->dev = dev;
> +
> + lcdb->regmap = dev_get_regmap(dev->parent, NULL);
> + if (!lcdb->regmap)
> + return dev_err_probe(dev, -ENODEV, "failed to get the parent
> regmap\n");
> +
> + ret = device_property_read_u32(dev, "reg", &lcdb->base);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to get the base
> address\n");
> +
> + ret = devm_mutex_init(dev, &lcdb->lock);
> + if (ret)
> + return ret;
> +
> + ret = qcom_lcdb_hw_init(lcdb);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to read the initial
> state\n");
> +
> + cfg.dev = dev;
> + cfg.regmap = lcdb->regmap;
> + cfg.driver_data = lcdb;
> +
> + for (i = 0; i < LCDB_NUM_RAILS; i++) {
> + lcdb->rdev[i] = devm_regulator_register(dev,
> &qcom_lcdb_descs[i], &cfg);
> + if (IS_ERR(lcdb->rdev[i]))
> + return dev_err_probe(dev, PTR_ERR(lcdb->rdev[i]),
> + "failed to register %s\n",
> + qcom_lcdb_descs[i].name);
> + }
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return irq;
> +
> + return devm_request_threaded_irq(dev, irq, NULL, qcom_lcdb_sc_irq,
> + IRQF_ONESHOT, "lcdb-sc", lcdb);
> +}
> +
> +static const struct of_device_id qcom_lcdb_match[] = {
> + { .compatible = "qcom,pm8150l-lcdb" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, qcom_lcdb_match);
> +
> +static struct platform_driver qcom_lcdb_driver = {
> + .driver = {
> + .name = "qcom-lcdb-regulator",
> + .of_match_table = qcom_lcdb_match,
> + },
> + .probe = qcom_lcdb_probe,
> +};
> +module_platform_driver(qcom_lcdb_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm LCDB (LCD bias) regulator driver");
> +MODULE_LICENSE("GPL");
>
