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a9fb41b5de
Preserve the I/O register bits in __ast_write8_i_masked() as specified by preserve_mask. Accidentally OR-ing the output value into these will overwrite the register's previous settings. Fixes display output on the AST2300, where the screen can go blank at boot. The driver's original commit312fec1405("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)") already added the broken code. Commit6f719373b9("drm/ast: Blank with VGACR17 sync enable, always clear VGACRB6 sync off") triggered the bug. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reported-by: Peter Schneider <pschneider1968@googlemail.com> Closes: https://lore.kernel.org/dri-devel/a40caf8e-58ad-4f9c-af7f-54f6f69c29bb@googlemail.com/ Tested-by: Peter Schneider <pschneider1968@googlemail.com> Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com> Fixes:6f719373b9("drm/ast: Blank with VGACR17 sync enable, always clear VGACRB6 sync off") Fixes:312fec1405("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)") Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Nick Bowler <nbowler@draconx.ca> Cc: Douglas Anderson <dianders@chromium.org> Cc: Dave Airlie <airlied@redhat.com> Cc: Jocelyn Falempe <jfalempe@redhat.com> Cc: dri-devel@lists.freedesktop.org Cc: <stable@vger.kernel.org> # v3.5+ Link: https://patch.msgid.link/20251024073626.129032-1-tzimmermann@suse.de
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.