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Andreas Kempe
34d9d5c81e
commitaede83625fupstream. As part of driver initialization, e.g. st_lsm6dsx_init_shub() selects the shub register page using st_lsm6dsx_set_page(). Selecting the shub register page shadows the regular register space so whoami, among other registers, is no longer accessible. In applications where the IMU is permanently powered separately from the processor, there is a window where a reset of the CPU leaves the IMU in the shub register page. Once this occurs, any subsequent probe attempt fails because of the register shadowing. Using the ism330dlc, the error typically looks like st_lsm6dsx_i2c 3-006a: unsupported whoami [10] with the unknown whoami read from a reserved register in the shub page. The reset register is also shadowed by the page select, preventing a reset from recovering the chip. Unconditionally clear the shub page before the whoami readout to ensure normal register access and allow the initialization to proceed. Place the fix in st_lsm6dsx_check_whoami() before the whoami check because hw->settings, which st_lsm6dsx_set_page() relies on, is first assigned in that function. Placing the fix in a more logical place than the whoami check would require a bigger restructuring of the code. Fixes:c91c1c844e("iio: imu: st_lsm6dsx: add i2c embedded controller support") Signed-off-by: Andreas Kempe <andreas.kempe@actia.se> Acked-by: Lorenzo Bianconi <lorenzo@kernel.org> Cc: <Stable@vger.kernel.org> Signed-off-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.