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.\" Copyright (c) 2017, Joyent, Inc.
.\" Copyright 2022 Oxide Computer Company
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.Dd July 2, 2022
.Dt MAC_TX_UPDATE 9F
.Os
.Sh NAME
.Nm mac_tx_update ,
.Nm mac_tx_ring_update
.Nd indicate that a device can transmit again
.Sh SYNOPSIS
.In sys/mac_provider.h
.Ft void
.Fo mac_tx_update
.Fa "mac_handle_t mh"
.Fc
.Ft void
.Fo mac_tx_ring_update
.Fa "mac_handle_t mh"
.Fa "mac_ring_handle_t mrh"
.Fc
.Sh INTERFACE LEVEL
illumos DDI specific
.Pp
The
.Fn mac_tx_ring_update
function point is
.Sy Uncommitted -
API and ABI stability is not guaranteed.
.Sh PARAMETERS
.Bl -tag -width Fa
.It Fa mh
The MAC handle obtained from a call to
.Xr mac_register 9F .
.It Fa mrh
The MAC ring handle obtained when the driver's ring entry point
.Xr mr_rget 9E
was called.
.El
.Sh DESCRIPTION
The
.Fn mac_tx_update
function is used by device drivers to indicate that the device
represented by the handle
.Fa mh
can transmit data again.
It should only be called after the device driver has returned data from its
.Xr mc_tx 9E
endpoint.
For more information on when this should be called, see both
.Xr mc_tx 9E
and the
.Sx Transmitting Data and Back Pressure
section of
.Xr mac 9E .
.Pp
Device drivers should not hold any of their own locks when calling into
this function.
See the
.Sx MAC Callbacks
section of
.Xr mac 9E
for more information.
.Pp
When a driver has negotiated the
.Dv MAC_CAPAB_RINGS
capability and indicated that it supports transmit groups, it must not
use the
.Fn mac_tx_update
function and should instead call the
.Fn mac_tx_ring_update
function targeting a specific ring instead.
The ring that is being updated is specified by the ring handle passed in
the
.Fa mrh
argument.
The ring should have previously returned frames from its
.Xr mri_tx 9E
entry point to indicate that it was blocked.
.Pp
In all other respects, the
.Fn mac_tx_ring_update
function is similar to the
.Fn mac_tx_update
function.
.Sh CONTEXT
The
.Fn mac_tx_update
function may be called from
.Sy user ,
.Sy kernel ,
or
.Sy interrupt
context.
.Sh SEE ALSO
.Xr mac 9E ,
.Xr mac_capab_rings 9E ,
.Xr mc_tx 9E ,
.Xr mr_rget 9E ,
.Xr mri_tx 9E ,
.Xr mac_register 9F