diff options
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_hdmi.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 780a19a75c3f..874c6bd787c5 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2869,6 +2869,7 @@ static int vc4_hdmi_runtime_resume(struct device *dev) struct vc4_hdmi *vc4_hdmi = dev_get_drvdata(dev); unsigned long __maybe_unused flags; u32 __maybe_unused value; + unsigned long rate; int ret; /* @@ -2884,6 +2885,21 @@ static int vc4_hdmi_runtime_resume(struct device *dev) if (ret) return ret; + /* + * Whenever the RaspberryPi boots without an HDMI monitor + * plugged in, the firmware won't have initialized the HSM clock + * rate and it will be reported as 0. + * + * If we try to access a register of the controller in such a + * case, it will lead to a silent CPU stall. Let's make sure we + * prevent such a case. + */ + rate = clk_get_rate(vc4_hdmi->hsm_clock); + if (!rate) { + ret = -EINVAL; + goto err_disable_clk; + } + if (vc4_hdmi->variant->reset) vc4_hdmi->variant->reset(vc4_hdmi); @@ -2905,6 +2921,10 @@ static int vc4_hdmi_runtime_resume(struct device *dev) #endif return 0; + +err_disable_clk: + clk_disable_unprepare(vc4_hdmi->hsm_clock); + return ret; } static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) |