From: Dom Cobley Date: Fri, 21 Jun 2024 15:20:40 +0000 (+0100) Subject: drm/vc4: hdmi: Avoid hang with debug registers when suspended X-Git-Tag: v6.13-rc1~122^2~23^2~75 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=223ee2567a55e4f80315c768d2969e6a3b9fb23d;p=thirdparty%2Fkernel%2Flinux.git drm/vc4: hdmi: Avoid hang with debug registers when suspended 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: 25eb441d55d4 ("drm/vc4: hdmi: Add all the vc5 HDMI registers into the debugfs dumps") Signed-off-by: Dom Cobley Reviewed-by: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20240621152055.4180873-17-dave.stevenson@raspberrypi.com Signed-off-by: Dave Stevenson --- diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 60cbf1d4c7dd1..28792dfa8c556 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;