forked from Minki/linux
net: cdc_ncm: document the sysfs API
Adding documentation for all the driver specific sysfs attributes. Cc: Peter Stuge <peter@stuge.se> Signed-off-by: Bjørn Mork <bjorn@mork.no> Signed-off-by: David S. Miller <davem@davemloft.net>
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Bjørn Mork
David S. Miller
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149
Documentation/ABI/testing/sysfs-class-net-cdc_ncm
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149
Documentation/ABI/testing/sysfs-class-net-cdc_ncm
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What: /sys/class/net/<iface>/cdc_ncm/min_tx_pkt
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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The driver will pad NCM Transfer Blocks (NTBs) longer
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than this to tx_max, allowing the device to receive
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tx_max sized frames with no terminating short
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packet. NTBs shorter than this limit are transmitted
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as-is, without any padding, and are terminated with a
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short USB packet.
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Padding to tx_max allows the driver to transmit NTBs
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back-to-back without any interleaving short USB
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packets. This reduces the number of short packet
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interrupts in the device, and represents a tradeoff
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between USB bus bandwidth and device DMA optimization.
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Set to 0 to pad all frames. Set greater than tx_max to
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disable all padding.
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What: /sys/class/net/<iface>/cdc_ncm/rx_max
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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The maximum NTB size for RX. Cannot exceed the
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maximum value supported by the device. Must allow at
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least one max sized datagram plus headers.
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The actual limits are device dependent. See
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dwNtbInMaxSize.
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Note: Some devices will silently ignore changes to
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this value, resulting in oversized NTBs and
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corresponding framing errors.
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What: /sys/class/net/<iface>/cdc_ncm/tx_max
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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The maximum NTB size for TX. Cannot exceed the
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maximum value supported by the device. Must allow at
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least one max sized datagram plus headers.
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The actual limits are device dependent. See
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dwNtbOutMaxSize.
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What: /sys/class/net/<iface>/cdc_ncm/tx_timer_usecs
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Datagram aggregation timeout in µs. The driver will
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wait up to 3 times this timeout for more datagrams to
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aggregate before transmitting an NTB frame.
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Valid range: 5 to 4000000
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Set to 0 to disable aggregation.
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The following read-only attributes all represent fields of the
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structure defined in section 6.2.1 "GetNtbParameters" of "Universal
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Serial Bus Communications Class Subclass Specifications for Network
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Control Model Devices" (CDC NCM), Revision 1.0 (Errata 1), November
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24, 2010 from USB Implementers Forum, Inc. The descriptions are
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quoted from table 6-3 of CDC NCM: "NTB Parameter Structure".
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What: /sys/class/net/<iface>/cdc_ncm/bmNtbFormatsSupported
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Bit 0: 16-bit NTB supported (set to 1)
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Bit 1: 32-bit NTB supported
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Bits 2 – 15: reserved (reset to zero; must be ignored by host)
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What: /sys/class/net/<iface>/cdc_ncm/dwNtbInMaxSize
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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IN NTB Maximum Size in bytes
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What: /sys/class/net/<iface>/cdc_ncm/wNdpInDivisor
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Divisor used for IN NTB Datagram payload alignment
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What: /sys/class/net/<iface>/cdc_ncm/wNdpInPayloadRemainder
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Remainder used to align input datagram payload within
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the NTB: (Payload Offset) mod (wNdpInDivisor) =
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wNdpInPayloadRemainder
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What: /sys/class/net/<iface>/cdc_ncm/wNdpInAlignment
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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NDP alignment modulus for NTBs on the IN pipe. Shall
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be a power of 2, and shall be at least 4.
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What: /sys/class/net/<iface>/cdc_ncm/dwNtbOutMaxSize
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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OUT NTB Maximum Size
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What: /sys/class/net/<iface>/cdc_ncm/wNdpOutDivisor
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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OUT NTB Datagram alignment modulus
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What: /sys/class/net/<iface>/cdc_ncm/wNdpOutPayloadRemainder
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Remainder used to align output datagram payload
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offsets within the NTB: Padding, shall be transmitted
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as zero by function, and ignored by host. (Payload
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Offset) mod (wNdpOutDivisor) = wNdpOutPayloadRemainder
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What: /sys/class/net/<iface>/cdc_ncm/wNdpOutAlignment
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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NDP alignment modulus for use in NTBs on the OUT
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pipe. Shall be a power of 2, and shall be at least 4.
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What: /sys/class/net/<iface>/cdc_ncm/wNtbOutMaxDatagrams
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Date: May 2014
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KernelVersion: 3.16
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Maximum number of datagrams that the host may pack
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into a single OUT NTB. Zero means that the device
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imposes no limit.
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