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Allow disabling FIFOs on PL011 UART #5794

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Allow disabling FIFOs on PL011 UART #5794

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Commits on Dec 15, 2023

  1. amba_pl011: Add disable-fifos DT property. 

    The BCM2835 PL011 implementation assumes that Rx/Tx FIFOs should be
always enabled. Although this is desirable for most of the time, there
are rare occasions when FIFOs introduce unwanted delay on the line.
The delay is unnoticeable for the common UART use cases but it can lead
to communication failures in UART-based protocols expecting fast
responses, such as eBUS.

Add a "disable-fifos" property to Pi DTBs and use the presence of that
property to forcefully set FIFOs size to 1, and prevent FIFOs from being
enabled.

Signed-off-by: Bak, Krzysztof <github@bittern.com.pl>
    @ITachiLab
    ITachiLab committed Dec 15, 2023
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  2. overlays: uart0: Allow disabling FIFOs. 

    Add a "disable_fifos" switch to existing "uart0-overlay.dts". The new
switch can be used to disable FIFOs on PL011 (uart0).

Signed-off-by: Bak, Krzysztof <github@bittern.com.pl>
    @ITachiLab
    ITachiLab committed Dec 15, 2023
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