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| author | Hans de Goede <hdegoede@redhat.com> | 2023-02-23 00:42:26 +0300 |
|---|---|---|
| committer | Hans de Goede <hdegoede@redhat.com> | 2023-03-07 14:08:31 +0300 |
| commit | 607fbac0fccba506b4f9e47994504121db776956 (patch) | |
| tree | a1117086f32ec9d6d82633db417a13ed9e2824e2 /drivers/platform/x86/x86-android-tablets | |
| parent | 9b1d2662b8c586eb10cb939c7ae2c25bb36d2b61 (diff) | |
| download | linux-607fbac0fccba506b4f9e47994504121db776956.tar.xz | |
platform/x86: x86-android-tablets: Add backlight ctrl for Lenovo Yoga Tab 3 Pro YT3-X90F
The YT3 uses an TI LP8557 LED backlight controller, the LP8557's PWM input
is connected to a PWM output coming from the LCD panel's controller.
The Android kernel has a hack in the i915 driver to write the non-standard
DSI reg 0x51 with the desired level to set the duty-cycle of the LCD's PWM.
To avoid having to have a similar hack in the mainline kernel program
instantiate an i2c-client for the LP8557 with platform-data to have
the LP8557 to directly set the level (ignoring its PWM input), this allows
backlight brightness control through a backlight device registered by
the lp855x_bl driver.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230301092331.7038-13-hdegoede@redhat.com
Diffstat (limited to 'drivers/platform/x86/x86-android-tablets')
| -rw-r--r-- | drivers/platform/x86/x86-android-tablets/lenovo.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/platform/x86/x86-android-tablets/lenovo.c b/drivers/platform/x86/x86-android-tablets/lenovo.c index 4ba4b1e8c7d0..e9eae09784ef 100644 --- a/drivers/platform/x86/x86-android-tablets/lenovo.c +++ b/drivers/platform/x86/x86-android-tablets/lenovo.c @@ -346,6 +346,20 @@ static const struct software_node lenovo_yt3_hideep_ts_node = { .properties = lenovo_yt3_hideep_ts_props, }; +/* + * The YT3 uses an TI LP8557 LED backlight controller, the LP8557's PWM input is + * connected to a PWM output coming from the LCD panel's controller. The Android + * kernel has a hack in the i915 driver to write the non-standard DSI reg 0x51 + * with the desired level to set the duty-cycle of the LCD's PWM output. + * + * 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. + */ +static struct lp855x_platform_data lenovo_yt3_lp8557_pdata = { + .device_control = 0x86, + .initial_brightness = 128, +}; + static const struct x86_i2c_client_info lenovo_yt3_i2c_clients[] __initconst = { { /* bq27500 fuel-gauge for the flat lipo battery behind the screen */ @@ -397,6 +411,15 @@ static const struct x86_i2c_client_info lenovo_yt3_i2c_clients[] __initconst = { .trigger = ACPI_LEVEL_SENSITIVE, .polarity = ACPI_ACTIVE_LOW, }, + }, { + /* LP8557 Backlight controller */ + .board_info = { + .type = "lp8557", + .addr = 0x2c, + .dev_name = "lp8557", + .platform_data = &lenovo_yt3_lp8557_pdata, + }, + .adapter_path = "\\_SB_.PCI0.I2C1", } }; |