[Letux-kernel] [PATCH v16 1/4] drm/bridge: dw-hdmi: introduce dw_hdmi_enable_poll()

[H. Nikolaus Schaller]

Hi Paul, Neil,

> Am 04.03.2022 um 17:47 schrieb Paul Cercueil <paul at crapouillou.net>:
> 
> From what I understood in Nikolaus' last message, HDMI hotplug is actually correctly detected, so there's no need for polling. What is missing is the call to drm_kms_helper_hotplug_event *somewhere*, so that the information is correctly relayed to userspace.

Exactly.

As Maxime pointed out it should already be called by drm_helper_hpd_irq_event() in dw_hdmi_irq() but isn't
because mode_config.poll_enabled isn't enabled.

So we can either
a) enable mode_config.poll_enabled so that it is called by drm_helper_hpd_irq_event() or

b) make drm_kms_helper_hotplug_event() being called explicitly in dw_hdmi_irq().
   We could guard that by mode_config.poll_enabled to avoid drm_kms_helper_hotplug_event()
   being called twice (but I think the "changed" mechanism will take care of).

> I think this issue can be fixed by calling drm_bridge_connector_enable_hpd() on the connector in ingenic-drm-drv.c.

I don't see yet how this would solve it, but it may work.

Anyways, this all is a missing feature (sometimes called "bug") of the *dw-hdmi driver* and IMHO
neither of the connector nor the ingenic-drm-drv.

So I think it should not be solved outside dw-hdmi.

BR and thanks,
Nikolaus