mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-10 22:22:51 -04:00
6640727fc5
Provide an `ecr_writable' parameter to `__parport_pc_probe_port' so that
callers can specify a mask of bits to modify on ECR writes.
To avoid the need for separate bit set and bit clear masks always set
bit 0 whenever a non-zero mask has been set, as all the currently known
cases where a mask is required, that is Oxford Semiconductor devices, do
require this bit to be set. If further cases are discovered where the
bit is required to be clear, we can update code accordingly, but chances
are very low as the bit is supposed to be read-only[1].
Skip ECR probing, which can be problematic as the Oxford Semiconductor
OX12PCI840 part has been reported to lock up on setting bit 2, whenever
a non-zero mask has been requested by a port subdriver, assuming that
the ECR must be there if the subdriver has requested a specific way to
access it.
References:
[1] "Extended Capabilities Port Protocol and ISA Interface Standard",
Microsoft Corporation, Revision: 1.14, July 14, 1993, Table 14
"Extended Control Register"
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Link: https://lore.kernel.org/r/20230108215656.6433-3-sudipm.mukherjee@gmail.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 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.