Messages in this thread | | | Date | Mon, 13 Apr 2020 13:25:13 +0200 | From | Paul Cercueil <> | Subject | Re: DRM interaction problems on Ingenic CI20 / jz4780 with dw-hdmi and ingenic-drm |
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Hi Nikolaus,
Le sam. 11 avril 2020 à 16:14, H. Nikolaus Schaller <hns@goldelico.com> a écrit : > Hi, > we (Paul Boddie and me) are working to get HDMI functional on the > Ingenic CI20 board with jz4780 SoC which uses a specialization of > the dw-hdmi driver. > > > So far we have identified two issues. > > The first is that HPD interrupts are not properly processed. > > drm_helper_hpd_irq_event() is called by HPD events but > dev->mode_config.poll_enabled is false. > > Therefore the interrupt is ignored and nothing happens. > > Now I wonder about the logic behind checking for poll_enabled. > I understand that a driver can do either polling or irq or both. > > Therefore handling the irq_event shouldn't be disabled by poll_enabled > being false. Otherwise we can only do: nothing, polling, polling+irq > but not irq alone. > > The jz4780 hdmi subsystem (drm/bridge/dw-hdmi.c) uses > > connector->polled = DRM_CONNECTOR_POLL_HPD; > > but shouldn't this enable polling? Note that there seems to be > no (direct) call to drm_kms_helper_poll_init(). > > If we set dev->mode_config.poll_enabled = true in > drm_helper_hpd_irq_event() things start to work. > > Please can you clarify what would be best practise here to > get HPD event handling working. > > > The other issue is in dw-hdmi.c: > > We found out that ingenic_drm_encoder_atomic_check() fails because > > info->num_bus_formats == 0 > > and not 1. This blocks further initialization. > > The reason seems to be that dw_hdmi_bridge_attach() does not call > drm_display_info_set_bus_formats() with a proper format like > other drivers (e.g. drm/bridge/ti-tfp410.c) are doing. > > We have patched to set a single bus format MEDIA_BUS_FMT_RGB888_1X24 > and then DRM setup seems to work (although we still have no valid > HDMI signal but that is likely something else). > > Please can you explain how setting the bus format should be fixed > in dw-hdmi.c. > > If these questions should be forwarded to other specialists, please > do so.
It should be sent to the DRI mailing list, you missed the most important one.
-Paul
> > BR and thanks, > Nikolaus Schaller
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