On Tue, Dec 17, 2013 at 09:12:42AM -0600, Daniel Drake wrote: > On Mon, Dec 16, 2013 at 5:40 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > > Have a bit of logic in the exynos ->detect function to re-try a 2nd > > round of edid probing after each hdp interrupt if the first one > > returns an -ENXIO. Only tricky part is to be careful with edge > > detection so that userspace gets all the hotplug events still. > > Presuming you don't have any funkiness with reprobing causing yet > > another hpd interrupt and stuff like that (seen it all), as long as > > you're using the helpers in drm_crtc_helper.c it should all be working > > correctly. So you want a work item which just grabs all modeset locks > > and then calls drm_helper_probe_single_connector_modes or something on > > the right connector. > > Thanks for the tips. Having trouble sticking to those details though. > exynos_drm_connector_detect() is actually a long way away from EDID > probing so it is hard to detect the ENXIO case there. Yeah, was a bit hand-wavy ;-) > What happens here is: > exynos hdmi_irq_thread() calls drm_helper_hpd_irq_event() > That then calls exynos_drm_connector_detect(), which returns a simple > "yes, hpd detection says we are connected" > Then it calls drm_kms_helper_hotplug_event() for which the call chain is: > > drm_kms_helper_hotplug_event > exynos_drm_output_poll_changed > drm_fb_helper_hotplug_event > drm_fb_helper_probe_connector_mode > exynos_drm_connector_fill_modes > drm_helper_probe_single_connector_modes > exynos_drm_connector_get_modes > drm_get_edid > drm_do_get_edid > drm_do_probe_ddc_edid <-- ENXIO in here > > drm_do_probe_ddc_edid actually swallows the ENXIO code and just > returns -1, so that particular error is indistinguishable from others. > > Trying to follow your suggestions, the closest would seem to be something like: > > 1. Modify exynos_drm_connector_detect to read and cache the EDID right > away. If EDID read fails for any reason, report "no connection" and > schedule a work item to retry the EDID read. If the later EDID read > succeeds, call drm_kms_helper_hotplug_event() > > 2. Modify exynos_drm_connector_get_modes to return cached EDID I think we can do it simpler. When you get a hpd interrupt you eventually call drm_helper_hpd_irq_event which will update all the state and poke connectors. I'd just create a delay_work which you launch from hdmi_irq_thread with a 1 second delay which again calls drm_helper_hpd_irq_event. That way you won't miss the EDID (presuming the user isn't _really_ careful with pluggin in the cable slowly). It's a bit inefficient but also doesn't really matter since hpd don't happen often. And when they do userspace usually wants to do a modeset anyway, so an added 30ms to read the edid twice won't really hurt. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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