[PATCH v10 30/69] drm/rockchip: dw_hdmi_qp: Cancel pending HPD work on suspend

The HPD threaded handler debounces hotplug events by delaying
hdmi->hpd_work for 150 ms.  Nothing discards that work when the system
goes to sleep: drm_kms_helper_poll_disable() only disables the HPD IRQ
line via the bridge .hpd_disable() op, and disable_irq() merely waits
for the threaded handler, which has already returned after arming the
timer.

If the debounce expires during suspend, its non-freezable work may probe
the connector and read the EDID over DDC.  Since genpd powers off the
HDMI controller's power domain in ->suspend_noirq(), this access may
hit unpowered hardware and hang the system.

Cancel the work in the suspend callback.  The DRM device is registered
as a consumer of the HDMI device, so it always suspends first and the
HPD IRQ is already disabled by that point, meaning nothing can re-arm
the work behind our back.  No counterpart is needed on resume, as the
work gets scheduled again on the next hotplug interrupt.

Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
Reported-by: Sashiko <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Cristian Ciocaltea <[email protected]>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index 646a4cb96830..e9fda67b8ca9 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -728,8 +728,12 @@ static int __maybe_unused dw_hdmi_qp_rockchip_suspend(struct device *dev)
 {
 	struct rockchip_hdmi_qp *hdmi = dev_get_drvdata(dev);
 
-	if (hdmi)
-		dw_hdmi_qp_suspend(dev, hdmi->hdmi);
+	if (!hdmi)
+		return 0;
+
+	dw_hdmi_qp_suspend(dev, hdmi->hdmi);
+
+	cancel_delayed_work_sync(&hdmi->hpd_work);
 
 	return 0;
 }

-- 
2.55.0