What: /sys/class/net//cdc_ncm/min_tx_pkt Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: The driver will pad NCM Transfer Blocks (NTBs) longer than this to tx_max, allowing the device to receive tx_max sized frames with no terminating short packet. NTBs shorter than this limit are transmitted as-is, without any padding, and are terminated with a short USB packet. Padding to tx_max allows the driver to transmit NTBs back-to-back without any interleaving short USB packets. This reduces the number of short packet interrupts in the device, and represents a tradeoff between USB bus bandwidth and device DMA optimization. Set to 0 to pad all frames. Set greater than tx_max to disable all padding. What: /sys/class/net//cdc_ncm/ndp_to_end Date: Dec 2015 KernelVersion: 4.5 Contact: Bjørn Mork Description: Boolean attribute showing the status of the "NDP to end" quirk. Defaults to 'N', except for devices already known to need it enabled. The "NDP to end" quirk makes the driver place the NDP (the packet index table) after the payload. The NCM specification does not mandate this, but some devices are known to be more restrictive. Write 'Y' to this attribute for temporary testing of a suspect device failing to work with the default driver settings. A device entry should be added to the driver if this quirk is found to be required. What: /sys/class/net//cdc_ncm/rx_max Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: The maximum NTB size for RX. Cannot exceed the maximum value supported by the device. Must allow at least one max sized datagram plus headers. The actual limits are device dependent. See dwNtbInMaxSize. Note: Some devices will silently ignore changes to this value, resulting in oversized NTBs and corresponding framing errors. What: /sys/class/net//cdc_ncm/tx_max Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: The maximum NTB size for TX. Cannot exceed the maximum value supported by the device. Must allow at least one max sized datagram plus headers. The actual limits are device dependent. See dwNtbOutMaxSize. What: /sys/class/net//cdc_ncm/tx_timer_usecs Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: Datagram aggregation timeout in µs. The driver will wait up to 3 times this timeout for more datagrams to aggregate before transmitting an NTB frame. Valid range: 5 to 4000000 Set to 0 to disable aggregation. The following read-only attributes all represent fields of the structure defined in section 6.2.1 "GetNtbParameters" of "Universal Serial Bus Communications Class Subclass Specifications for Network Control Model Devices" (CDC NCM), Revision 1.0 (Errata 1), November 24, 2010 from USB Implementers Forum, Inc. The descriptions are quoted from table 6-3 of CDC NCM: "NTB Parameter Structure". What: /sys/class/net//cdc_ncm/bmNtbFormatsSupported Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: - Bit 0: 16-bit NTB supported (set to 1) - Bit 1: 32-bit NTB supported - Bits 2 – 15: reserved (reset to zero; must be ignored by host) What: /sys/class/net//cdc_ncm/dwNtbInMaxSize Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: IN NTB Maximum Size in bytes What: /sys/class/net//cdc_ncm/wNdpInDivisor Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: Divisor used for IN NTB Datagram payload alignment What: /sys/class/net//cdc_ncm/wNdpInPayloadRemainder Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: Remainder used to align input datagram payload within the NTB: (Payload Offset) mod (wNdpInDivisor) = wNdpInPayloadRemainder What: /sys/class/net//cdc_ncm/wNdpInAlignment Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: NDP alignment modulus for NTBs on the IN pipe. Shall be a power of 2, and shall be at least 4. What: /sys/class/net//cdc_ncm/dwNtbOutMaxSize Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: OUT NTB Maximum Size What: /sys/class/net//cdc_ncm/wNdpOutDivisor Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: OUT NTB Datagram alignment modulus What: /sys/class/net//cdc_ncm/wNdpOutPayloadRemainder Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: Remainder used to align output datagram payload offsets within the NTB: Padding, shall be transmitted as zero by function, and ignored by host. (Payload Offset) mod (wNdpOutDivisor) = wNdpOutPayloadRemainder What: /sys/class/net//cdc_ncm/wNdpOutAlignment Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: NDP alignment modulus for use in NTBs on the OUT pipe. Shall be a power of 2, and shall be at least 4. What: /sys/class/net//cdc_ncm/wNtbOutMaxDatagrams Date: May 2014 KernelVersion: 3.16 Contact: Bjørn Mork Description: Maximum number of datagrams that the host may pack into a single OUT NTB. Zero means that the device imposes no limit.