The Xiaomi Mi Pad 2 tablet uses an ACPI enumerated LP8556 backlight controller for its LCD-panel, with a Xiaomi specific ACPI HID of "XMCC0001", add support for this.
Note the new "if (id)" check also fixes a NULL pointer deref when a user tries to manually bind the driver from sysfs.
When CONFIG_ACPI is disabled acpi_match_device() will always return NULL, so the lp855x_parse_acpi() call will get optimized away.
Signed-off-by: Hans de Goede hdegoede@redhat.com --- drivers/video/backlight/lp855x_bl.c | 70 ++++++++++++++++++++++++----- 1 file changed, 60 insertions(+), 10 deletions(-)
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c index d1d27d5eb0f2..f075ec84acfb 100644 --- a/drivers/video/backlight/lp855x_bl.c +++ b/drivers/video/backlight/lp855x_bl.c @@ -5,6 +5,7 @@ * Copyright (C) 2011 Texas Instruments */
+#include <linux/acpi.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/i2c.h> @@ -330,7 +331,7 @@ static int lp855x_parse_dt(struct lp855x *lp) { struct device *dev = lp->dev; struct device_node *node = dev->of_node; - struct lp855x_platform_data *pdata; + struct lp855x_platform_data *pdata = lp->pdata; int rom_length;
if (!node) { @@ -338,10 +339,6 @@ static int lp855x_parse_dt(struct lp855x *lp) return -EINVAL; }
- pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); - if (!pdata) - return -ENOMEM; - of_property_read_string(node, "bl-name", &pdata->name); of_property_read_u8(node, "dev-ctrl", &pdata->device_control); of_property_read_u8(node, "init-brt", &pdata->initial_brightness); @@ -379,8 +376,31 @@ static int lp855x_parse_dt(struct lp855x *lp) } #endif
+static int lp855x_parse_acpi(struct lp855x *lp) +{ + int ret; + + /* + * On ACPI the device has already been initialized by the firmware + * so we read back the settings from the registers. + */ + ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_brightness); + if (ret < 0) + return ret; + + lp->pdata->initial_brightness = ret; + + ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_devicectrl); + if (ret < 0) + return ret; + + lp->pdata->device_control = ret; + return 0; +} + static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id) { + const struct acpi_device_id *acpi_id = NULL; struct device *dev = &cl->dev; struct lp855x *lp; int ret; @@ -394,10 +414,20 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
lp->client = cl; lp->dev = dev; - lp->chipname = id->name; - lp->chip_id = id->driver_data; lp->pdata = dev_get_platdata(dev);
+ if (id) { + lp->chipname = id->name; + lp->chip_id = id->driver_data; + } else { + acpi_id = acpi_match_device(dev->driver->acpi_match_table, dev); + if (!acpi_id) + return -ENODEV; + + lp->chipname = acpi_id->id; + lp->chip_id = acpi_id->driver_data; + } + switch (lp->chip_id) { case LP8550: case LP8551: @@ -415,9 +445,19 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id) }
if (!lp->pdata) { - ret = lp855x_parse_dt(lp); - if (ret < 0) - return ret; + lp->pdata = devm_kzalloc(dev, sizeof(*lp->pdata), GFP_KERNEL); + if (!lp->pdata) + return -ENOMEM; + + if (id) { + ret = lp855x_parse_dt(lp); + if (ret < 0) + return ret; + } else { + ret = lp855x_parse_acpi(lp); + if (ret < 0) + return ret; + } }
if (lp->pdata->period_ns > 0) @@ -537,10 +577,20 @@ static const struct i2c_device_id lp855x_ids[] = { }; MODULE_DEVICE_TABLE(i2c, lp855x_ids);
+#ifdef CONFIG_ACPI +static const struct acpi_device_id lp855x_acpi_match[] = { + /* Xiaomi specific HID used for the LP8556 on the Mi Pad 2 */ + { "XMCC0001", LP8556 }, + { } +}; +MODULE_DEVICE_TABLE(acpi, lp855x_acpi_match); +#endif + static struct i2c_driver lp855x_driver = { .driver = { .name = "lp855x", .of_match_table = of_match_ptr(lp855x_dt_ids), + .acpi_match_table = ACPI_PTR(lp855x_acpi_match), }, .probe = lp855x_probe, .remove = lp855x_remove,