diff options
| -rw-r--r-- | drivers/platform/x86/x86-android-tablets/lenovo.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/drivers/platform/x86/x86-android-tablets/lenovo.c b/drivers/platform/x86/x86-android-tablets/lenovo.c index 0bc6a74b8beb..f1c66a61bfc5 100644 --- a/drivers/platform/x86/x86-android-tablets/lenovo.c +++ b/drivers/platform/x86/x86-android-tablets/lenovo.c @@ -34,12 +34,30 @@ * * 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[] = { @@ -122,7 +140,7 @@ static const struct x86_i2c_client_info lenovo_yb1_x90_i2c_clients[] __initconst .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", }, { @@ -358,7 +376,7 @@ static struct x86_i2c_client_info lenovo_yoga_tab2_830_1050_i2c_clients[] __init .type = "lp8557", .addr = 0x2c, .dev_name = "lp8557", - .platform_data = &lenovo_lp8557_pdata, + .platform_data = &lenovo_lp8557_pwm_and_reg_pdata, }, .adapter_path = "\\_SB_.I2C3", }, @@ -655,7 +673,7 @@ static const struct x86_i2c_client_info lenovo_yt3_i2c_clients[] __initconst = { .type = "lp8557", .addr = 0x2c, .dev_name = "lp8557", - .platform_data = &lenovo_lp8557_pdata, + .platform_data = &lenovo_lp8557_reg_only_pdata, }, .adapter_path = "\\_SB_.PCI0.I2C1", } |