[PATCH 5.10 12/25] drm/vc4: hdmi: Make sure the device is powered with CEC

Greg Kroah-Hartman
2022-02-04T09:21:40Z

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 | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1402,18 +1402,18 @@ 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;
-
- 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);
-
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);
+
HDMI_WRITE(HDMI_CEC_CNTRL_5, val |
VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET);
HDMI_WRITE(HDMI_CEC_CNTRL_5, val);
@@ -1439,7 +1439,10 @@ static int vc4_hdmi_cec_adap_enable(stru
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);
+
+ pm_runtime_put(&vc4_hdmi->pdev->dev);
}
+
return 0;
}

@@ -1531,8 +1534,6 @@ static int vc4_hdmi_cec_init(struct vc4_
if (ret < 0)
goto err_delete_cec_adap;

- pm_runtime_put(&vc4_hdmi->pdev->dev);
-
return 0;