diff options
Diffstat (limited to 'drivers/gpu/drm/vc4/vc4_hdmi.c')
| -rw-r--r-- | drivers/gpu/drm/vc4/vc4_hdmi.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 64f9feabf43e..596e311d6e58 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -3318,12 +3318,37 @@ 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; + /* + * The HSM clock is in the HDMI power domain, so we need to set + * its frequency while the power domain is active so that it + * keeps its rate. + */ + ret = clk_set_min_rate(vc4_hdmi->hsm_clock, HSM_MIN_CLOCK_FREQ); + if (ret) + return ret; + ret = clk_prepare_enable(vc4_hdmi->hsm_clock); 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); @@ -3345,6 +3370,10 @@ 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 void vc4_hdmi_put_ddc_device(void *ptr) |