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526daee730
ivtvfb was previously disabled for x86 PAT-enabled systems
by commit 1bf1735b47 ("x86/mm/pat, drivers/media/ivtv:
Use arch_phys_wc_add() and require PAT disabled") as a
workaround to abstract MTRR code away from device drivers.
The driver is not easily upgradable to the PAT-aware
ioremap_wc() API since the firmware hides the address
ranges that should be marked write-combined from the driver.
However, since a write-combined cache on the framebuffer
is only a performance enhancement not a requirement for
the framebuffer to function, completely disabling the driver
in this configuration is not necessary.
Add force_pat module parameter and a corresponding kernel
configuration parameter to optionally force initialization
on PAT-enabled x86 systems with a warning about the lack of
write-combined caching, and document the reasons the driver
cannot be easily updated to support wc caching on all systems.
Signed-off-by: Nick French <naf@ou.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: fix typo, split long pr_ lines up]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.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.