*
* To avoid having to have a similar hack in the mainline kernel program the
* LP8557 to directly set the level and use the lp855x_bl driver for control.
+ *
+ * The LP8557 can either be configured to multiply its PWM input and
+ * the I2C register set level (requiring both to be at 100% for 100% output);
+ * or to only take the I2C register set level into account.
+ *
+ * Multiplying the 2 levels is useful because this will turn off the backlight
+ * when the panel goes off and turns off its PWM output.
+ *
+ * But on some models the panel's PWM output defaults to a duty-cycle of
+ * much less then 100%, severely limiting max brightness. In this case
+ * the LP8557 should be configured to only take the I2C register into
+ * account and the i915 driver must turn off the panel and the backlight
+ * separately using e.g. VBT MIPI sequences to turn off the backlight.
*/
-static struct lp855x_platform_data lenovo_lp8557_pdata = {
+static struct lp855x_platform_data lenovo_lp8557_pwm_and_reg_pdata = {
.device_control = 0x86,
.initial_brightness = 128,
};
+static struct lp855x_platform_data lenovo_lp8557_reg_only_pdata = {
+ .device_control = 0x85,
+ .initial_brightness = 128,
+};
+
/* Lenovo Yoga Book X90F / X90L's Android factory img has everything hardcoded */
static const struct property_entry lenovo_yb1_x90_wacom_props[] = {
.type = "lp8557",
.addr = 0x2c,
.dev_name = "lp8557",
- .platform_data = &lenovo_lp8557_pdata,
+ .platform_data = &lenovo_lp8557_pwm_and_reg_pdata,
},
.adapter_path = "\\_SB_.PCI0.I2C4",
}, {
.type = "lp8557",
.addr = 0x2c,
.dev_name = "lp8557",
- .platform_data = &lenovo_lp8557_pdata,
+ .platform_data = &lenovo_lp8557_pwm_and_reg_pdata,
},
.adapter_path = "\\_SB_.I2C3",
},
.type = "lp8557",
.addr = 0x2c,
.dev_name = "lp8557",
- .platform_data = &lenovo_lp8557_pdata,
+ .platform_data = &lenovo_lp8557_reg_only_pdata,
},
.adapter_path = "\\_SB_.PCI0.I2C1",
}