Hi Paul, > Am 04.03.2022 um 19:41 schrieb H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>: > > > >> Am 04.03.2022 um 19:33 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>: >> >> >> >> Le ven., mars 4 2022 at 19:15:13 +0100, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit : >>> 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/ >> >> Looks correct to me. It has been reviewed by two people so I believe it will be merged very soon. > > Great. I will try asap. If it works we can drop all our private ideas... > > And focus on the last missing piece for jz4780 HDMI: the output format negotiation (which still is not working properly - but I have to analyse why). Yes, it works. And I see you have merged it to drm-misc-next so that I can build on it. So there is only the bus format negotiation to be understood and finally solved for v17. Great and thanks, Nikolaus
