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On some MAX 10 cards, the BMC firmware is not available to service handshake registers during secure update erase and write phases at normal speeds. This problem affects at least hwmon driver. When the MAX 10 hwmon driver tries to read the sensor values during a secure update, the reads are slowed down (e.g., reading all D5005 sensors takes ~24s which is magnitudes worse than the normal <0.02s). Manage access to the handshake registers using a rw semaphore and a FW state variable to prevent accesses during those secure update phases and return -EBUSY instead. If handshake_sys_reg_nranges == 0, don't update bwcfw_state as it is not used. This avoids the locking cost. Co-developed-by: Russ Weight <russell.h.weight@intel.com> Signed-off-by: Russ Weight <russell.h.weight@intel.com> Co-developed-by: Xu Yilun <yilun.xu@intel.com> Signed-off-by: Xu Yilun <yilun.xu@intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Lee Jones <lee@kernel.org> Link: https://lore.kernel.org/r/20230417092653.16487-5-ilpo.jarvinen@linux.intel.com
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.