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The xHCI driver allocates various port-related structures based on the maximum number of ports reported by the controller. The Number of Ports (MaxPorts) field occupies bits 31:24 of the HCSPARAMS1 register and can represent values up to 255. However, the 'HCS_MAX_PORTS()' macro currently reads bits 30:24, effectively limiting the maximum to 127. Fixing the macro increases the reported port limit to 255, which in turn increases memory usage regardless of how many ports are actually used. To maintain compatibility and control memory consumption, set 'xhci->max_ports' to the minimum of the value read from 'HCS_MAX_PORTS()' and 127 (MAX_HC_PORTS). This preserves the existing limit while making the restriction explicit and easier to adjust in the future. Summary: * Port allocations are now limited to 127. * HC max ports macro now correctly reads the MaxPorts value. * Macro 'MAX_HC_PORTS' can be modified to set the port limit. Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://patch.msgid.link/20251119142417.2820519-17-mathias.nyman@linux.intel.com 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 reStructuredText 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.