diff options
| author | Maxime Ripard <maxime@cerno.tech> | 2022-09-29 11:21:18 +0200 |
|---|---|---|
| committer | Maxime Ripard <maxime@cerno.tech> | 2022-10-13 13:57:04 +0200 |
| commit | 4190e8bbcbc77a9c36724681801cedc5229e7fc2 (patch) | |
| tree | 306415aeec6bc0a93af0efd612f31fdacfd97407 | |
| parent | ae71ab585c819f83aec84f91eb01157a90552ef2 (diff) | |
drm/vc4: hdmi: Check the HSM rate at runtime_resumedrm-misc-fixes-2022-10-13
If our HSM clock has not been properly initialized, any register access
will silently lock up the system.
Let's check that this can't happen by adding a check for the rate before
any register access, and error out otherwise.
Link: https://lore.kernel.org/dri-devel/20220922145448.w3xfywkn5ecak2et@pengutronix.de/
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220929-rpi-pi3-unplugged-fixes-v1-2-cd22e962296c@cerno.tech
| -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) |