Am Donnerstag, 29. Oktober 2026, 08:53:36 Mitteleuropäische Normalzeit schrieb
Michal Wilczynski:
> inno_hdmi_irq() passes hdmi->bridge.dev to drm_helper_hpd_irq_event(),
> which dereferences it in its first statement:
>
> if (!dev->mode_config.poll_enabled)
>
> bridge.dev is assigned only by drm_bridge_attach(), but inno_hdmi_bind()
> unmutes the hotplug interrupt in inno_hdmi_init_hw() and installs the
> handler well before it attaches the bridge:
>
> inno_hdmi_init_hw(hdmi); /* unmutes hotplug */
> devm_request_threaded_irq(...); /* handler goes live */
> ...
> hdmi->bridge.ddc = inno_hdmi_i2c_adapter(hdmi);
> devm_drm_bridge_add(dev, &hdmi->bridge);
> drm_bridge_attach(...); /* bridge.dev set here */
>
> The bridge is allocated by devm_drm_bridge_alloc(), which kzalloc()s it,
> so bridge.dev is NULL for all of that window, and a hotplug event
> arriving in it enters drm_helper_hpd_irq_event(NULL).
>
> Before the conversion to a bridge the ordering was safe:
> inno_hdmi_register() called drmm_connector_hdmi_init(), which set
> connector.dev, before the interrupt was requested.
>
> Drop hotplug events that arrive before the bridge is attached.
>
> Fixes: 969325a2597e ("drm/rockchip: inno-hdmi: Convert to drm bridge")
> Signed-off-by: Michal Wilczynski <[email protected]>
> ---
> drivers/gpu/drm/bridge/inno-hdmi.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/inno-hdmi.c
> b/drivers/gpu/drm/bridge/inno-hdmi.c
> index
> d7c33b92e2ddf4ced84d17304463f44be52270b8..d29832249b942dec84fb9d07a0b21ee751fc0486
> 100644
> --- a/drivers/gpu/drm/bridge/inno-hdmi.c
> +++ b/drivers/gpu/drm/bridge/inno-hdmi.c
> @@ -929,7 +929,13 @@ static irqreturn_t inno_hdmi_irq(int irq, void *dev_id)
> {
> struct inno_hdmi *hdmi = dev_id;
>
> - drm_helper_hpd_irq_event(hdmi->bridge.dev);
> + /*
> + * The interrupt is requested before the bridge is attached, and
> + * bridge.dev is only set by drm_bridge_attach(). Drop hotplug events
> + * that arrive before then rather than dereference a NULL drm_device.
> + */
> + if (hdmi->bridge.dev)
> + drm_helper_hpd_irq_event(hdmi->bridge.dev);
Reviewed-by: Heiko Stuebner <[email protected]>
Most other callers of drm_helper_hpd_irq_event() also do exactly this.
Heiko
