Documentation/ABI/testing/sysfs-class-net-cdc_ncm

Source file repositories/reference/linux-study-clean/Documentation/ABI/testing/sysfs-class-net-cdc_ncm

File Facts

System
Linux kernel
Corpus path
Documentation/ABI/testing/sysfs-class-net-cdc_ncm
Extension
[no extension]
Size
5452 bytes
Lines
169
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: Documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

What:		/sys/class/net/<iface>/cdc_ncm/min_tx_pkt
Date:		May 2014
KernelVersion:	3.16
Contact:	Bjørn Mork <bjorn@mork.no>
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/<iface>/cdc_ncm/ndp_to_end
Date:		Dec 2015
KernelVersion:	4.5
Contact:	Bjørn Mork <bjorn@mork.no>
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/<iface>/cdc_ncm/rx_max
Date:		May 2014
KernelVersion:	3.16
Contact:	Bjørn Mork <bjorn@mork.no>
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/<iface>/cdc_ncm/tx_max
Date:		May 2014
KernelVersion:	3.16
Contact:	Bjørn Mork <bjorn@mork.no>
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/<iface>/cdc_ncm/tx_timer_usecs
Date:		May 2014

Annotation

Implementation Notes