bc004f5038
There is a while-loop in ast_dp_set_on_off() that could lead to
infinite-loop. This is because the register, VGACRI-Dx, checked in
this API is a scratch register actually controlled by a MCU, named
DPMCU, in BMC.
These scratch registers are protected by scu-lock. If suc-lock is not
off, DPMCU can not update these registers and then host will have soft
lockup due to never updated status.
DPMCU is used to control DP and relative registers to handshake with
host's VGA driver. Even the most time-consuming task, DP's link
training, is less than 100ms. 200ms should be enough.
Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Fixes: 594e9c04b586 ("drm/ast: Create the driver for ASPEED proprietory Display-Port")
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: KuoHsiang Chou <kuohsiang_chou@aspeedtech.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.19+
Link: https://patchwork.freedesktop.org/patch/msgid/20240403090246.1495487-1-jammy_huang@aspeedtech.com
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.