From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- .../driver-api/backlight/lp855x-driver.rst | 81 ++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 Documentation/driver-api/backlight/lp855x-driver.rst (limited to 'Documentation/driver-api/backlight') diff --git a/Documentation/driver-api/backlight/lp855x-driver.rst b/Documentation/driver-api/backlight/lp855x-driver.rst new file mode 100644 index 000000000..1e0b224fc --- /dev/null +++ b/Documentation/driver-api/backlight/lp855x-driver.rst @@ -0,0 +1,81 @@ +==================== +Kernel driver lp855x +==================== + +Backlight driver for LP855x ICs + +Supported chips: + + Texas Instruments LP8550, LP8551, LP8552, LP8553, LP8555, LP8556 and + LP8557 + +Author: Milo(Woogyom) Kim + +Description +----------- + +* Brightness control + + Brightness can be controlled by the pwm input or the i2c command. + The lp855x driver supports both cases. + +* Device attributes + + 1) bl_ctl_mode + + Backlight control mode. + + Value: pwm based or register based + + 2) chip_id + + The lp855x chip id. + + Value: lp8550/lp8551/lp8552/lp8553/lp8555/lp8556/lp8557 + +Platform data for lp855x +------------------------ + +For supporting platform specific data, the lp855x platform data can be used. + +* name: + Backlight driver name. If it is not defined, default name is set. +* device_control: + Value of DEVICE CONTROL register. +* initial_brightness: + Initial value of backlight brightness. +* period_ns: + Platform specific PWM period value. unit is nano. + Only valid when brightness is pwm input mode. +* size_program: + Total size of lp855x_rom_data. +* rom_data: + List of new eeprom/eprom registers. + +Examples +======== + +1) lp8552 platform data: i2c register mode with new eeprom data:: + + #define EEPROM_A5_ADDR 0xA5 + #define EEPROM_A5_VAL 0x4f /* EN_VSYNC=0 */ + + static struct lp855x_rom_data lp8552_eeprom_arr[] = { + {EEPROM_A5_ADDR, EEPROM_A5_VAL}, + }; + + static struct lp855x_platform_data lp8552_pdata = { + .name = "lcd-bl", + .device_control = I2C_CONFIG(LP8552), + .initial_brightness = INITIAL_BRT, + .size_program = ARRAY_SIZE(lp8552_eeprom_arr), + .rom_data = lp8552_eeprom_arr, + }; + +2) lp8556 platform data: pwm input mode with default rom data:: + + static struct lp855x_platform_data lp8556_pdata = { + .device_control = PWM_CONFIG(LP8556), + .initial_brightness = INITIAL_BRT, + .period_ns = 1000000, + }; -- cgit v1.3.1