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bdb48e4c7d
When a serial port continuously experiences input overrun from
(1) continuous receive characters from remote and or (2) hardware
issues, its interrupt handler can preempt other tasks especially
when the system is busy (ie. boot up period). This can cause other
tasks to get starved of processing time from the CPU.
When this dts binding is enabled and input overrun on the serial port
is detected, serial port receive will be throttled to give some breathing
room for processing other tasks. Value provided will be in milliseconds.
&serial0{
overrun-throttle-ms = <500>;
};
Signed-off-by: Darwin Dingel <darwin.dingel@alliedtelesis.co.nz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
76 lines
2.6 KiB
Plaintext
76 lines
2.6 KiB
Plaintext
* UART (Universal Asynchronous Receiver/Transmitter)
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Required properties:
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- compatible : one of:
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- "ns8250"
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- "ns16450"
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- "ns16550a"
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- "ns16550"
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- "ns16750"
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- "ns16850"
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- For Tegra20, must contain "nvidia,tegra20-uart"
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- For other Tegra, must contain '"nvidia,<chip>-uart",
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"nvidia,tegra20-uart"' where <chip> is tegra30, tegra114, tegra124,
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tegra132, or tegra210.
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- "nxp,lpc3220-uart"
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- "ralink,rt2880-uart"
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- For MediaTek BTIF, must contain '"mediatek,<chip>-btif",
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"mediatek,mtk-btif"' where <chip> is mt7622, mt7623.
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- "altr,16550-FIFO32"
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- "altr,16550-FIFO64"
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- "altr,16550-FIFO128"
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- "fsl,16550-FIFO64"
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- "fsl,ns16550"
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- "ti,da830-uart"
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- "aspeed,ast2400-vuart"
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- "aspeed,ast2500-vuart"
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- "nuvoton,npcm750-uart"
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- "serial" if the port type is unknown.
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- reg : offset and length of the register set for the device.
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- interrupts : should contain uart interrupt.
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- clock-frequency : the input clock frequency for the UART
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or
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clocks phandle to refer to the clk used as per Documentation/devicetree
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/bindings/clock/clock-bindings.txt
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Optional properties:
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- current-speed : the current active speed of the UART.
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- reg-offset : offset to apply to the mapbase from the start of the registers.
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- reg-shift : quantity to shift the register offsets by.
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- reg-io-width : the size (in bytes) of the IO accesses that should be
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performed on the device. There are some systems that require 32-bit
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accesses to the UART (e.g. TI davinci).
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- used-by-rtas : set to indicate that the port is in use by the OpenFirmware
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RTAS and should not be registered.
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- no-loopback-test: set to indicate that the port does not implements loopback
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test mode
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- fifo-size: the fifo size of the UART.
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- auto-flow-control: one way to enable automatic flow control support. The
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driver is allowed to detect support for the capability even without this
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property.
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- tx-threshold: Specify the TX FIFO low water indication for parts with
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programmable TX FIFO thresholds.
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- resets : phandle + reset specifier pairs
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- overrun-throttle-ms : how long to pause uart rx when input overrun is encountered.
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Note:
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* fsl,ns16550:
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------------
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Freescale DUART is very similar to the PC16552D (and to a
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pair of NS16550A), albeit with some nonstandard behavior such as
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erratum A-004737 (relating to incorrect BRK handling).
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Represents a single port that is compatible with the DUART found
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on many Freescale chips (examples include mpc8349, mpc8548,
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mpc8641d, p4080 and ls2085a).
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Example:
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uart@80230000 {
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compatible = "ns8250";
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reg = <0x80230000 0x100>;
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clock-frequency = <3686400>;
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interrupts = <10>;
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reg-shift = <2>;
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};
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