Hi Paul, > Am 04.03.2022 um 19:04 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>: > > > > Le ven., mars 4 2022 at 18:51:14 +0100, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit : >> Hi Paul, Neil, >>> Am 04.03.2022 um 17:47 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>: >>> 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. > > dw_hdmi_irq() calls drm_bridge_hpd_notify(), which would call bridge->hpd_cb() if it was non-NULL. Ok, this is a case c). I vaguely remember having tried to analyse what bridge->hpd_cb is but stopped since it is NULL... > > Calling drm_bridge_connector_enable_hpd() will set the bridge->hpd_cb() callback to point to drm_bridge_connector_hpd_cb(), which itself will call drm_kms_helper_hotplug_event(). Therefore, all that is missing is one call to drm_bridge_connector_enable_hpd(). Ah, ok, I see. >> 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. Well, a little more analysis shows that drm_bridge_connector_enable_hpd is called in the *-drv.c for some other plaforms: https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/imx/dcss/dcss-dev.c#L292 https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/imx/dcss/dcss-kms.c#L145 https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/omapdrm/omap_drv.c#L393 https://elixir.bootlin.com/linux/v5.17-rc6/source/drivers/gpu/drm/msm/hdmi/hdmi.c#L317 >> So I think it should not be solved outside dw-hdmi. Hm. Can we call drm_bridge_connector_enable_hpd() from inside dw-hdmi? Or would this be the solution if merged? (I currently can't try code). https://lore.kernel.org/lkml/a7d0b013-6114-07b3-0a7b-0d17db8a3982@xxxxxxxxxxxxxxxxxx/T/ BR and thanks, Nikolaus
