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1226a1b2e5
The SPD5118 specification says, in its documentation of the page bits in the MR11 register: " This register only applies to non-volatile memory (1024) Bytes) access of SPD5 Hub device. For volatile memory access, this register must be programmed to '000'. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ " Renesas/ITD SPD5118 hub controllers take this literally and disable access to volatile memory if the page selected in MR11 is != 0. Since the BIOS or ROMMON will access the non-volatile memory and likely select a page != 0, this means that the driver will not instantiate since it can not identify the chip. Even if the driver instantiates, access to volatile registers is blocked after a nvram read operation which selects a page other than 0. To solve the problem, add initialization code to select page 0 during probe. Before doing that, use basic validation to ensure that this is really a SPD5118 device and not some random EEPROM. Cc: Sasha Kozachuk <skozachuk@google.com> Cc: John Hamrick <johnham@google.com> Cc: Chris Sarra <chrissarra@google.com> Tested-by: Armin Wolf <W_Armin@gmx.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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.