in the transmit code: the TX descriptor ring, and a 'shadow' ring of mbuf
pointers, one for each TX descriptor. When transmitting a packet that
consists of several fragments in an mbuf chain, we link each fragment
to a descriptor in the TX ring, but we only save a pointer to the mbuf
chain. This pointer is saved in the shadow ring entry which corresponds
to the first fragment in the packet. Later, ti_txeof() can release the
whole chain with a single m_freem() call. (We need the second ring to
keep track of the virtual addresses of the mbuf chains.)
The problem with this is that the Tigon isn't actually through with the
mbuf chain until it reaches the last fragment (which has the TI_BDFLAG_END
bit set), however the current scheme releases the mbuf chain as soon as
the first fragment is consumed. This is wrong, since the mbufs can then
be yanked out from under the Tigon and modified before the other fragments
can be transmitted.
The fix is to make a one line change to ti_encap() so that it saves the
mbuf chain pointer in the shadow ring entry that corresponds to the last
fragment in TX ring instead of the first. This prevents the mbufs from
being released until the last fragment is transmitted.
Painstakingly diagnosed and fixed by: Robert Picco <picco@mail.wevinc.com>
Brought to my attention by: dg
-------------------------------------------------------------------------------
Recent versions of 3.0-current have the bktr driver built in. Older versions
of 3.0 and all versions of 2.2 need to have the driver files installed by hand:
cp ioctl_bt848.h /sys/i386/include/
cp brktree_reg.h brooktree848.c /sys/pci/
In /sys/conf/files add:
pci/brooktree848.c optional bktr device-driver
-------------------------------------------------------------------------------
In all cases you will need to add the driver to your kernel:
In your kernel configuration file:
controller pci0 #if you already have this line don't add it.
device bktr0
There is no need to specify DMA channels nor interrupts for this
driver.
-------------------------------------------------------------------------------
Finally you need to create nodes for the driver:
Create a video device:
mknod /dev/bktr0 c 92 0
Create a tuner device:
mknod /dev/tuner0 c 92 16
-------------------------------------------------------------------------------
The code attempts to auto-probe code to detect card/tuner types.
The detected card is printed in the dmesg as the driver is loaded. If
this fails to detect the proper card you can override it in brooktree848.c:
#define OVERRIDE_CARD <card type>
where <card type> is one of:
CARD_UNKNOWN
CARD_MIRO
CARD_HAUPPAUGE
CARD_STB
CARD_INTEL
-------------------------------------------------------------------------------
This model now separates the "tuner control" items into a minor device:
minor device layout: xxxxxxxx xxxT UUUU
UUUU: the card (ie UNIT) identifier, 0 thru 15
T == 0: video device
T == 1: tuner device
Access your tuner ioctl thru your tuner device handle and anything
which controls the video capture process thru the video device handle.
Certain ioctl()s such as video source are available thru both devices.
-------------------------------------------------------------------------------
If your tuner does not work properly or is not recognized properly
try setting the tuner type via or card type:
sysctl -w hw.bt848.card=<integer> current valid values are 0 to 5 inclusive
sysctl -w hw.bt848.tuner=<integer> where integer is a value from 1 to 10
systcl -w hw.bt848.reverse_mute=<1 | 0> to reverse the mute function in the
driver set variable to 1.
The exact format of the sysctl bt848 variable is:
unit << 8 | value
unit identifies the pci bt848 board to be affected 0 is the first bt848
board, 1 is the second bt848 board.
value denotes the integer value for tuners is a value from 0 to 10 for
reversing the mute function of the tuner the value is 1 or 0.
to find out all the bt848 variables:
sysctl hw.bt848
-------------------------------------------------------------------------------
The bt848 driver consists of:
src/sys/i386/include/ioctl_bt848.h
src/sys/pci/brktree_reg.h
src/sys/pci/brooktree848.c
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