Re: [PATCH v3 02/13] drm: bridge: dw_hdmi: Only notify connected status on HPD interrupt

Nicolas Frattaroli
2026-04-27T18:05:09Z

On Friday, 3 April 2026 20:52:48 Central European Summer Time Jonas Karlman wrote:
> drm_helper_hpd_irq_event() and drm_bridge_hpd_notify() may incorrectly
> be called with a connected status when HPD is high and RX sense is
> changed. This typically happens when the HDMI cable is unplugged,
> shortly before the HPD is changed to low.
>
> The original intent of commit da09daf88108 ("drm: bridge: dw_hdmi: only
> trigger hotplug event on link change") was to signal hotplug event at
> correct interrupt states.
>
> Based on the commit message the intent was to trigger hotplug event:
> - when HPD goes high (plugin)
> - when both HPD and RX sense has gone low (plugout)
>
> However, following interrupt state changes can typically be observed
> when the HDMI cable is unplugged:
> - RX interrupt: HPD=high RX=low -> triggers a connected event
> - HPD interrupt: HPD=low RX=low -> triggers a disconnected event
>
> Fix this by only notify connected status on the HPD interrupt when HPD
> is going high, not on the RX sense interrupt when RX sense is changed.
>
> After this a connected event should be triggered when HPD=high at HPD
> interrupt, and a disconnected event should be triggered when both
> HPD=low and RX=low at either HPD or RX interrupt.
>
> Fixes: da09daf88108 ("drm: bridge: dw_hdmi: only trigger hotplug event on link change")
> Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
> ---
> v3: Update commit message
> v2: New patch
> ---
> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index 9febcb58a1df..3b851f12adfe 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -3140,7 +3140,8 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id)
> mutex_unlock(&hdmi->cec_notifier_mutex);
> }
>
> - if (phy_stat & HDMI_PHY_HPD)
> + if ((intr_stat & HDMI_IH_PHY_STAT0_HPD) &&
> + (phy_stat & HDMI_PHY_HPD))
> status = connector_status_connected;
>
> if (!(phy_stat & (HDMI_PHY_HPD | HDMI_PHY_RX_SENSE)))
>

Reviewed-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>