forked from Minki/linux
media: cec-core.rst: include cec-pin.h and cec-notifier.h
Include the CEC pin framework documentation by reading cec-pin.h. Include the CEC notifier framework documentation by reading cec-notifier.h. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Reviewed-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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@ -345,3 +345,34 @@ log_addrs->num_log_addrs set to 0. The block argument is ignored when
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unconfiguring. This function will just return if the physical address is
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invalid. Once the physical address becomes valid, then the framework will
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attempt to claim these logical addresses.
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CEC Pin framework
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-----------------
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Most CEC hardware operates on full CEC messages where the software provides
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the message and the hardware handles the low-level CEC protocol. But some
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hardware only drives the CEC pin and software has to handle the low-level
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CEC protocol. The CEC pin framework was created to handle such devices.
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Note that due to the close-to-realtime requirements it can never be guaranteed
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to work 100%. This framework uses highres timers internally, but if a
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timer goes off too late by more than 300 microseconds wrong results can
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occur. In reality it appears to be fairly reliable.
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One advantage of this low-level implementation is that it can be used as
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a cheap CEC analyser, especially if interrupts can be used to detect
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CEC pin transitions from low to high or vice versa.
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.. kernel-doc:: include/media/cec-pin.h
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CEC Notifier framework
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-----------------
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Most drm HDMI implementations have an integrated CEC implementation and no
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notifier support is needed. But some have independent CEC implementations
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that have their own driver. This could be an IP block for an SoC or a
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completely separate chip that deals with the CEC pin. For those cases a
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drm driver can install a notifier and use the notifier to inform the
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CEC driver about changes in the physical address.
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.. kernel-doc:: include/media/cec-notifier.h
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