[PATCH 6.13 181/443] drm/ast: astdp: Fix timeout for enabling video signal

Greg Kroah-Hartman gregkh at linuxfoundation.org
Thu Feb 13 14:25:46 UTC 2025


6.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Zimmermann <tzimmermann at suse.de>

commit fd39c41bcd82d5ebaaebadb944eab5598c668a90 upstream.

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.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
Fixes: 4e29cc7c5c67 ("drm/ast: astdp: Replace ast_dp_set_on_off()")
Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Jocelyn Falempe <jfalempe at redhat.com>
Cc: Dave Airlie <airlied at redhat.com>
Cc: dri-devel at lists.freedesktop.org
Cc: <stable at vger.kernel.org> # v6.13+
Reviewed-by: Jocelyn Falempe <jfalempe at redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250127134423.84266-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/gpu/drm/ast/ast_dp.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/ast/ast_dp.c
+++ b/drivers/gpu/drm/ast/ast_dp.c
@@ -195,7 +195,7 @@ static bool __ast_dp_wait_enable(struct
 	if (enabled)
 		vgacrdf_test |= AST_IO_VGACRDF_DP_VIDEO_ENABLE;
 
-	for (i = 0; i < 200; ++i) {
+	for (i = 0; i < 1000; ++i) {
 		if (i)
 			mdelay(1);
 		vgacrdf = ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xdf,




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