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Machine resets via da9062/da9063 PMICs are challenging since one needs to use special i2c atomic transfers due to the fact interrupts are disabled in such late system stages. This is the reason both PMICs don't use regmap and have instead opted for i2c_smbus_write_byte_data() in restart handlers. However extensive testing revealed that even using atomic safe function is not enough and occasional resets fail with error message "Failed to shutdown (err = -11)". This is due to the fact that function i2c_smbus_write_byte_data() in turn calls __i2c_lock_bus_helper() which might fail with -EAGAIN when bus lock is already taken and cannot be released anymore. Thus replace i2c_smbus_write_byte_data() with unlocked flavor of i2c_smbus_xfer() function to avoid above dead-lock scenario. At this system stage we don't care about proper locking anymore and only want proper machine reset to be carried out. Signed-off-by: Primoz Fiser <primoz.fiser@norik.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20221216083645.2574077-1-primoz.fiser@norik.com [groeck: Fixed continuation line alignment] Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.