1What: /sys/class/net/<iface>/cdc_ncm/min_tx_pkt 2Date: May 2014 3KernelVersion: 3.16 4Contact: Bjørn Mork <bjorn@mork.no> 5Description: 6 The driver will pad NCM Transfer Blocks (NTBs) longer 7 than this to tx_max, allowing the device to receive 8 tx_max sized frames with no terminating short 9 packet. NTBs shorter than this limit are transmitted 10 as-is, without any padding, and are terminated with a 11 short USB packet. 12 13 Padding to tx_max allows the driver to transmit NTBs 14 back-to-back without any interleaving short USB 15 packets. This reduces the number of short packet 16 interrupts in the device, and represents a tradeoff 17 between USB bus bandwidth and device DMA optimization. 18 19 Set to 0 to pad all frames. Set greater than tx_max to 20 disable all padding. 21 22What: /sys/class/net/<iface>/cdc_ncm/rx_max 23Date: May 2014 24KernelVersion: 3.16 25Contact: Bjørn Mork <bjorn@mork.no> 26Description: 27 The maximum NTB size for RX. Cannot exceed the 28 maximum value supported by the device. Must allow at 29 least one max sized datagram plus headers. 30 31 The actual limits are device dependent. See 32 dwNtbInMaxSize. 33 34 Note: Some devices will silently ignore changes to 35 this value, resulting in oversized NTBs and 36 corresponding framing errors. 37 38What: /sys/class/net/<iface>/cdc_ncm/tx_max 39Date: May 2014 40KernelVersion: 3.16 41Contact: Bjørn Mork <bjorn@mork.no> 42Description: 43 The maximum NTB size for TX. Cannot exceed the 44 maximum value supported by the device. Must allow at 45 least one max sized datagram plus headers. 46 47 The actual limits are device dependent. See 48 dwNtbOutMaxSize. 49 50What: /sys/class/net/<iface>/cdc_ncm/tx_timer_usecs 51Date: May 2014 52KernelVersion: 3.16 53Contact: Bjørn Mork <bjorn@mork.no> 54Description: 55 Datagram aggregation timeout in µs. The driver will 56 wait up to 3 times this timeout for more datagrams to 57 aggregate before transmitting an NTB frame. 58 59 Valid range: 5 to 4000000 60 61 Set to 0 to disable aggregation. 62 63The following read-only attributes all represent fields of the 64structure defined in section 6.2.1 "GetNtbParameters" of "Universal 65Serial Bus Communications Class Subclass Specifications for Network 66Control Model Devices" (CDC NCM), Revision 1.0 (Errata 1), November 6724, 2010 from USB Implementers Forum, Inc. The descriptions are 68quoted from table 6-3 of CDC NCM: "NTB Parameter Structure". 69 70What: /sys/class/net/<iface>/cdc_ncm/bmNtbFormatsSupported 71Date: May 2014 72KernelVersion: 3.16 73Contact: Bjørn Mork <bjorn@mork.no> 74Description: 75 Bit 0: 16-bit NTB supported (set to 1) 76 Bit 1: 32-bit NTB supported 77 Bits 2 – 15: reserved (reset to zero; must be ignored by host) 78 79What: /sys/class/net/<iface>/cdc_ncm/dwNtbInMaxSize 80Date: May 2014 81KernelVersion: 3.16 82Contact: Bjørn Mork <bjorn@mork.no> 83Description: 84 IN NTB Maximum Size in bytes 85 86What: /sys/class/net/<iface>/cdc_ncm/wNdpInDivisor 87Date: May 2014 88KernelVersion: 3.16 89Contact: Bjørn Mork <bjorn@mork.no> 90Description: 91 Divisor used for IN NTB Datagram payload alignment 92 93What: /sys/class/net/<iface>/cdc_ncm/wNdpInPayloadRemainder 94Date: May 2014 95KernelVersion: 3.16 96Contact: Bjørn Mork <bjorn@mork.no> 97Description: 98 Remainder used to align input datagram payload within 99 the NTB: (Payload Offset) mod (wNdpInDivisor) = 100 wNdpInPayloadRemainder 101 102What: /sys/class/net/<iface>/cdc_ncm/wNdpInAlignment 103Date: May 2014 104KernelVersion: 3.16 105Contact: Bjørn Mork <bjorn@mork.no> 106Description: 107 NDP alignment modulus for NTBs on the IN pipe. Shall 108 be a power of 2, and shall be at least 4. 109 110What: /sys/class/net/<iface>/cdc_ncm/dwNtbOutMaxSize 111Date: May 2014 112KernelVersion: 3.16 113Contact: Bjørn Mork <bjorn@mork.no> 114Description: 115 OUT NTB Maximum Size 116 117What: /sys/class/net/<iface>/cdc_ncm/wNdpOutDivisor 118Date: May 2014 119KernelVersion: 3.16 120Contact: Bjørn Mork <bjorn@mork.no> 121Description: 122 OUT NTB Datagram alignment modulus 123 124What: /sys/class/net/<iface>/cdc_ncm/wNdpOutPayloadRemainder 125Date: May 2014 126KernelVersion: 3.16 127Contact: Bjørn Mork <bjorn@mork.no> 128Description: 129 Remainder used to align output datagram payload 130 offsets within the NTB: Padding, shall be transmitted 131 as zero by function, and ignored by host. (Payload 132 Offset) mod (wNdpOutDivisor) = wNdpOutPayloadRemainder 133 134What: /sys/class/net/<iface>/cdc_ncm/wNdpOutAlignment 135Date: May 2014 136KernelVersion: 3.16 137Contact: Bjørn Mork <bjorn@mork.no> 138Description: 139 NDP alignment modulus for use in NTBs on the OUT 140 pipe. Shall be a power of 2, and shall be at least 4. 141 142What: /sys/class/net/<iface>/cdc_ncm/wNtbOutMaxDatagrams 143Date: May 2014 144KernelVersion: 3.16 145Contact: Bjørn Mork <bjorn@mork.no> 146Description: 147 Maximum number of datagrams that the host may pack 148 into a single OUT NTB. Zero means that the device 149 imposes no limit. 150