HDMI Hotplug Detection Fix #4538
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A quick test with LE/kodi looks good, but I get two warning splats when putting the TV out of standby - the same happens with kodi stopped and just console active full dmesg: http://ix.io/3wtp |
The drm_helper_hpd_irq_event() function is iterating over all the connectors when an hotplug event is detected. During that iteration, it will call each connector detect function and figure out if its status changed. Finally, if any connector changed, it will notify the user-space and the clients that something changed on the DRM device. This is supposed to be used for drivers that don't have a hotplug interrupt for individual connectors. However, drivers that can use an interrupt for a single connector are left in the dust and can either reimplement the logic used during the iteration for each connector or use that helper and iterate over all connectors all the time. Since both are suboptimal, let's create a helper that will only perform the status detection on a single connector. Signed-off-by: Maxime Ripard <maxime@cerno.tech>
The drm_helper_hpd_irq_event() documentation states that this function is "useful for drivers which can't or don't track hotplug interrupts for each connector." and that "Drivers which support hotplug interrupts for each connector individually and which have a more fine-grained detect logic should bypass this code and directly call drm_kms_helper_hotplug_event()". This is thus what we ended-up doing. However, what this actually means, and is further explained in the drm_kms_helper_hotplug_event() documentation, is that drm_kms_helper_hotplug_event() should be called by drivers that can track the connection status change, and if it has changed we should call that function. This underlying expectation we failed to provide is that the caller of drm_kms_helper_hotplug_event() should call drm_helper_probe_detect() to probe the new status of the connector. Since we didn't do it, it meant that even though we were sending the notification to user-space and the DRM clients that something changed we never probed or updated our internal connector status ourselves. This went mostly unnoticed since the detect callback usually doesn't have any side-effect. Also, if we were using the DRM fbdev emulation (which is a DRM client), or any user-space application that can deal with hotplug events, chances are they would react to the hotplug event by probing the connector status eventually. However, now that we have to enable the scrambler in detect() if it was enabled it has a side effect, and an application such as Kodi or modetest doesn't deal with hotplug events. This resulted with a black screen when Kodi or modetest was running when a screen was disconnected and then reconnected, or switched off and on. Signed-off-by: Maxime Ripard <maxime@cerno.tech>
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The new version I just pushed fixes the warning |
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Thanks, the updated version works fine here, too |
popcornmix
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kernel: HDMI Hotplug Detection Fix See: raspberrypi/linux#4538
popcornmix
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kernel: HDMI Hotplug Detection Fix See: raspberrypi/linux#4538
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Hi,
Here's a fix for a hotplug detection issue that ultimately resulted in a black screen when using a mode using the scrambler, an application that doesn't handle hotplug events and an hotplug event.
Fixes #4486