vc4/hdmi: Ignore hotplug interrupt with force_hotplug #6123
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Looks reasonable. I was wondering whether it is better to not register the interrupt handler if force_hotplug was set, but I guess this way you can dynamically enable and disable force_hotplug via /sys/module/vc4/parameters/force_hotplug. |
The intention of the vc4.force_hotplug setting is to ignore hotplug completely. It can be used when a display toggles hotplug when switching AV inputs, going into standby or changing a KVM switch, and some side effect of that is unwanted. It turns out while vc4.force_hotplug currently makes hotplug always read as asserted, that isn't enough to stop drm doing lots of stuff, including re-reading the edid. An example of what drm does with a hotplug deasert/assert and vc4.force_hotplug=1 currently is: https://paste.debian.net/hidden/dc07434b/ That is unwanted. Lets ignore the hotplug interrupt completely so drm is blissfully unaware of the hotplug change. Signed-off-by: Dom Cobley <popcornmix@gmail.com>
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Thanks, a few quick tests on RPi5 and RPi4 look fine, no more log messages with drm.debug=0x07 when hotplug is de- and re-asserted. |
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See: raspberrypi/linux#6113 kernel: DRM: rp1: rp1-dsi: Fix escape clock divider and timeouts See: raspberrypi/linux#6120 kernel: vc4/hdmi: Ignore hotplug interrupt with force_hotplug See: raspberrypi/linux#6123 kernel: drivers: media: cfe: Add remap entries for mono formats See: raspberrypi/linux#6122 kernel: dw-axi-dmac-platform: Avoid trampling with zero length buffer See: raspberrypi/linux#6118 kernel: Add a strict_gpiod option See: raspberrypi/linux#6117 kernel: Unicam FS/FE timing GPIO See: raspberrypi/linux#6088
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See: raspberrypi/linux#6113 kernel: DRM: rp1: rp1-dsi: Fix escape clock divider and timeouts See: raspberrypi/linux#6120 kernel: vc4/hdmi: Ignore hotplug interrupt with force_hotplug See: raspberrypi/linux#6123 kernel: drivers: media: cfe: Add remap entries for mono formats See: raspberrypi/linux#6122 kernel: dw-axi-dmac-platform: Avoid trampling with zero length buffer See: raspberrypi/linux#6118 kernel: Add a strict_gpiod option See: raspberrypi/linux#6117 kernel: Unicam FS/FE timing GPIO See: raspberrypi/linux#6088
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The intention of the vc4.force_hotplug setting is to ignore hotplug completely.
It can be used when a display switching AV inputs, or going into stanbdby or changing a KVM switch
toggles hotplug and some side effect of that is unwanted.
It turns out while vc4.force_hotplug currently makes hotplug always read as asserted, that isn't enough to stop drm doing lots of stuff, including re-reading the edid.
An example of what drm does with a hotplug deasert/assert and vc4.force_hotplug=1 currently is:
https://paste.debian.net/hidden/dc07434b/
That is unwanted. Lets ignore the hotplug interrupt completely so drm is blissfully unaware of the hotplug change.