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drm/vc4: hdmi: Avoid hang with debug registers when suspended

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Trying to read /sys/kernel/debug/dri/1/hdmi1_regs
when the hdmi is disconnected results in a fatal system hang.

This is due to the pm suspend code disabling the dvp clock.
That is just a gate of the 108MHz clock in DVP_HT_RPI_MISC_CONFIG,
which results in accesses hanging AXI bus.

Protect against this.

Fixes: 25eb441d55 ("drm/vc4: hdmi: Add all the vc5 HDMI registers into the debugfs dumps")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240621152055.4180873-17-dave.stevenson@raspberrypi.com
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
This commit is contained in:
Dom Cobley
2024-06-21 16:20:40 +01:00
committed by Dave Stevenson
parent 542962190e
commit 223ee2567a
1 changed files with 4 additions and 0 deletions
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4
drivers/gpu/drm/vc4/vc4_hdmi.c
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@@ -147,6 +147,8 @@ static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
if (!drm_dev_enter(drm, &idx))
return -ENODEV;
WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
drm_print_regset32(&p, &vc4_hdmi->hdmi_regset);
drm_print_regset32(&p, &vc4_hdmi->hd_regset);
drm_print_regset32(&p, &vc4_hdmi->cec_regset);
@@ -156,6 +158,8 @@ static int vc4_hdmi_debugfs_regs(struct seq_file *m, void *unused)
drm_print_regset32(&p, &vc4_hdmi->ram_regset);
drm_print_regset32(&p, &vc4_hdmi->rm_regset);
pm_runtime_put(&vc4_hdmi->pdev->dev);
drm_dev_exit(idx);
return 0;