diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index ee293f061f0a..5d5c4e9a8621 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -79,6 +79,7 @@ # define VC4_HD_M_SW_RST BIT(2) # define VC4_HD_M_ENABLE BIT(0) +#define HSM_MIN_CLOCK_FREQ 120000000 #define CEC_CLOCK_FREQ 40000 #define VC4_HSM_MID_CLOCK 149985000 @@ -1806,6 +1807,19 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) vc4_hdmi->disable_wifi_frequencies = of_property_read_bool(dev->of_node, "wifi-2.4ghz-coexistence"); + /* + * If we boot without any cable connected to the HDMI connector, + * the firmware will skip the HSM initialization and leave it + * with a rate of 0, resulting in a bus lockup when we're + * accessing the registers even if it's enabled. + * + * Let's put a sensible default at runtime_resume so that we + * don't end up in this situation. + */ + ret = clk_set_min_rate(vc4_hdmi->hsm_clock, HSM_MIN_CLOCK_FREQ); + if (ret) + goto err_put_ddc; + if (vc4_hdmi->variant->reset) vc4_hdmi->variant->reset(vc4_hdmi);