On Sat, Feb 05, 2022 at 09:12:38AM -0800, Guenter Roeck wrote:
> On Fri, Feb 04, 2022 at 10:22:15AM +0100, Greg Kroah-Hartman wrote:
> > From: Maxime Ripard <maxime@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxxx> # 5.10.x
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.15.x
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.16.x
> > Reported-by: Michael Stapelberg <michael+drm@xxxxxxxxxxxxx>
> > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > ---
> > 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.
Yeah, something is really wrong here. I'm going to go revert this for
now and push out a new set of releases with that fixed.
thanks for the review.
greg k-h
