git.openwrt.org Git - openwrt/openwrt.git/blob

   1 From db41506f785ad84895a31b01e8bd7c07bceabb3d Mon Sep 17 00:00:00 2001
   2 From: Dom Cobley <popcornmix@gmail.com>
   3 Date: Tue, 5 Sep 2023 19:38:24 +0100
   4 Subject: [PATCH 0597/1085] drm/vc4: hdmi: Avoid hang with debug registers when
   5  suspended
   6
   7 Trying to read /sys/kernel/debug/dri/1/hdmi1_regs
   8 when the hdmi is disconnected results in a fatal system hang.
   9
  10 This is due to the pm suspend code disabling the dvp clock.
  11 That is just a gate of the 108MHz clock in DVP_HT_RPI_MISC_CONFIG,
  12 which results in accesses hanging AXI bus.
  13
  14 Protect against this.
  15
  16 Signed-off-by: Dom Cobley <popcornmix@gmail.com>
  17 ---
  18  drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++++
  19  1 file changed, 4 insertions(+)
  20
  21 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
  22 +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
  23 @@ -185,6 +185,8 @@ static int vc4_hdmi_debugfs_regs(struct
  24         if (!drm_dev_enter(drm, &idx))
  25                 return -ENODEV;
  26
  27 +       WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
  28 +
  29         drm_print_regset32(&p, &vc4_hdmi->hdmi_regset);
  30         drm_print_regset32(&p, &vc4_hdmi->hd_regset);
  31         drm_print_regset32(&p, &vc4_hdmi->cec_regset);
  32 @@ -194,6 +196,8 @@ static int vc4_hdmi_debugfs_regs(struct
  33         drm_print_regset32(&p, &vc4_hdmi->ram_regset);
  34         drm_print_regset32(&p, &vc4_hdmi->rm_regset);
  35
  36 +       pm_runtime_put(&vc4_hdmi->pdev->dev);
  37 +
  38         drm_dev_exit(idx);
  39
  40         return 0;