On Fri, Feb 04, 2022 at 10:22:15AM +0100, Greg Kroah-Hartman wrote:
From: Maxime Ripard maxime@cerno.tech
Commit 20b0dfa86bef0e80b41b0e5ac38b92f23b6f27f9 upstream.
The original commit depended on a rework commit (724fc856c09e ("drm/vc4: hdmi: Split the CEC disable / enable functions in two")) that (rightfully) didn't reach stable.
However, probably because the context changed, when the patch was applied to stable the pm_runtime_put called got moved to the end of the vc4_hdmi_cec_adap_enable function (that would have become vc4_hdmi_cec_disable with the rework) to vc4_hdmi_cec_init.
This means that at probe time, we now drop our reference to the clocks and power domains and thus end up with a CPU hang when the CPU tries to access registers.
The call to pm_runtime_resume_and_get() is also problematic since the .adap_enable CEC hook is called both to enable and to disable the controller. That means that we'll now call pm_runtime_resume_and_get() at disable time as well, messing with the reference counting.
The behaviour we should have though would be to have pm_runtime_resume_and_get() called when the CEC controller is enabled, and pm_runtime_put when it's disabled.
We need to move things around a bit to behave that way, but it aligns stable with upstream.
Cc: stable@vger.kernel.org # 5.10.x Cc: stable@vger.kernel.org # 5.15.x Cc: stable@vger.kernel.org # 5.16.x Reported-by: Michael Stapelberg michael+drm@stapelberg.ch Signed-off-by: Maxime Ripard maxime@cerno.tech Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
drivers/gpu/drm/vc4/vc4_hdmi.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -1738,18 +1738,18 @@ static int vc4_hdmi_cec_adap_enable(stru u32 val; int ret;
- ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
- if (ret)
return ret;
- if (enable) {
ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);if (ret)return ret;
- val = HDMI_READ(HDMI_CEC_CNTRL_5);
- val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET |
VC4_HDMI_CEC_CNT_TO_4700_US_MASK |VC4_HDMI_CEC_CNT_TO_4500_US_MASK);- val |= ((4700 / usecs) << VC4_HDMI_CEC_CNT_TO_4700_US_SHIFT) |
((4500 / usecs) << VC4_HDMI_CEC_CNT_TO_4500_US_SHIFT);
val = HDMI_READ(HDMI_CEC_CNTRL_5);val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET |VC4_HDMI_CEC_CNT_TO_4700_US_MASK |VC4_HDMI_CEC_CNT_TO_4500_US_MASK);val |= ((4700 / usecs) << VC4_HDMI_CEC_CNT_TO_4700_US_SHIFT) |((4500 / usecs) << VC4_HDMI_CEC_CNT_TO_4500_US_SHIFT);
Unfortunately this is broken because it leaves the still existing else path with
if (!vc4_hdmi->variant->external_irq_controller) HDMI_WRITE(HDMI_CEC_CPU_MASK_SET, VC4_HDMI_CPU_CEC); HDMI_WRITE(HDMI_CEC_CNTRL_5, val | VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET);
where 'val' is now uninitialized. I don't know how to fix this up properly, so I won't even try.
Guenter