strategy used in the 3Com Linux driver. The new strategy is to use transmit
descriptor polling -- that is, the NIC polls the descriptors to see when
new packets are available for transmission. The advantage to the new scheme
is that no register accesses are needed in the transmit routine. The old
scheme requires several register accesses to stall the TX engine, update the
TX DMA list pointer register, then unstall the TX engine. Hopefully the new
scheme will provide improved transmit performance with less CPU overhead.
This only affects the 3c90xB or 3c90xC cards, not the 3c90x cards. This
means the original 3c900 and 3c905 cards are unaffected. Newer cards include
the 3c900B series, the 3c905B, 3c980, 3c980B, 3c905C and 3c905C, and the
3cSOHO100-TX OfficeConnect.
-------------------------------------------------------------------------------
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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