Messages in this thread | | | Date | Fri, 04 Mar 2022 18:33:59 +0000 | From | Paul Cercueil <> | Subject | Re: [Letux-kernel] [PATCH v16 1/4] drm/bridge: dw-hdmi: introduce dw_hdmi_enable_poll() |
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Le ven., mars 4 2022 at 19:15:13 +0100, H. Nikolaus Schaller <hns@goldelico.com> a écrit : > Hi Paul, > >> Am 04.03.2022 um 19:04 schrieb Paul Cercueil <paul@crapouillou.net>: >> >> >> >> Le ven., mars 4 2022 at 18:51:14 +0100, H. Nikolaus Schaller >> <hns@goldelico.com> a écrit : >>> Hi Paul, Neil, >>>> Am 04.03.2022 um 17:47 schrieb Paul Cercueil >>>> <paul@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. >> >> 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@cogentembedded.com/T/
Looks correct to me. It has been reviewed by two people so I believe it will be merged very soon.
Cheers, -Paul
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