From: Dom Cobley <popcornmix@xxxxxxxxx> 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. Signed-off-by: Dom Cobley <popcornmix@xxxxxxxxx> Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 21046056f63d..372ac2140001 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -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; -- 2.34.1
