CVE-2025-21747

In the Linux kernel, the following vulnerability has been resolved:

drm/ast: astdp: Fix timeout for enabling video signal

The ASTDP transmitter sometimes takes up to 1 second for enabling the
video signal, while the timeout is only 200 msec. This results in a
kernel error message. Increase the timeout to 1 second. An example
of the error message is shown below.

[  697.084433] ------------[ cut here ]------------
[  697.091115] ast 0000:02:00.0: [drm] drm_WARN_ON(!__ast_dp_wait_enable(ast, enabled))
[  697.091233] WARNING: CPU: 1 PID: 160 at drivers/gpu/drm/ast/ast_dp.c:232 ast_dp_set_enable+0x123/0x140 [ast]
[...]
[  697.272469] RIP: 0010:ast_dp_set_enable+0x123/0x140 [ast]
[...]
[  697.415283] Call Trace:
[  697.420727]  <TASK>
[  697.425908]  ? show_trace_log_lvl+0x196/0x2c0
[  697.433304]  ? show_trace_log_lvl+0x196/0x2c0
[  697.440693]  ? drm_atomic_helper_commit_modeset_enables+0x30a/0x470
[  697.450115]  ? ast_dp_set_enable+0x123/0x140 [ast]
[  697.458059]  ? __warn.cold+0xaf/0xca
[  697.464713]  ? ast_dp_set_enable+0x123/0x140 [ast]
[  697.472633]  ? report_bug+0x134/0x1d0
[  697.479544]  ? handle_bug+0x58/0x90
[  697.486127]  ? exc_invalid_op+0x13/0x40
[  697.492975]  ? asm_exc_invalid_op+0x16/0x20
[  697.500224]  ? preempt_count_sub+0x14/0xc0
[  697.507473]  ? ast_dp_set_enable+0x123/0x140 [ast]
[  697.515377]  ? ast_dp_set_enable+0x123/0x140 [ast]
[  697.523227]  drm_atomic_helper_commit_modeset_enables+0x30a/0x470
[  697.532388]  drm_atomic_helper_commit_tail+0x58/0x90
[  697.540400]  ast_mode_config_helper_atomic_commit_tail+0x30/0x40 [ast]
[  697.550009]  commit_tail+0xfe/0x1d0
[  697.556547]  drm_atomic_helper_commit+0x198/0x1c0

This is a cosmetical problem. Enabling the video signal still works
even with the error message. The problem has always been present, but
only recent versions of the ast driver warn about missing the timeout.