Hi folks,
recently, a laptop featuring a rtl8187b usb wifi adapter, precisely,
this one:
Bus 001 Device 002: ID 0bda:8197 Realtek Semiconductor Corp. RTL8187B Wireless Adapter
fell into my hands. I noticed that in my IPv6 enabled home network,
the card would not receive any RAs and thus not acquire an IPv6
address. So I thought I'd have a look at the respective driver code,
with the intention of probably being able to fix this and submit a
patch. However, I have to admit that now I'm stuck and could use some
help. :-)
The relevant section of code, in
linux/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c, is certainly
this here:
static void rtl8187_configure_filter(struct ieee80211_hw *dev,
unsigned int changed_flags,
unsigned int *total_flags,
u64 multicast)
{
struct rtl8187_priv *priv = dev->priv;
if (changed_flags & FIF_FCSFAIL)
priv->rx_conf ^= RTL818X_RX_CONF_FCS;
if (changed_flags & FIF_CONTROL)
priv->rx_conf ^= RTL818X_RX_CONF_CTRL;
if (changed_flags & FIF_OTHER_BSS)
priv->rx_conf ^= RTL818X_RX_CONF_MONITOR;
if (*total_flags & FIF_ALLMULTI || multicast > 0)
priv->rx_conf |= RTL818X_RX_CONF_MULTICAST;
else
priv->rx_conf &= ~RTL818X_RX_CONF_MULTICAST;
*total_flags = 0;
if (priv->rx_conf & RTL818X_RX_CONF_FCS)
*total_flags |= FIF_FCSFAIL;
if (priv->rx_conf & RTL818X_RX_CONF_CTRL)
*total_flags |= FIF_CONTROL;
if (priv->rx_conf & RTL818X_RX_CONF_MONITOR)
*total_flags |= FIF_OTHER_BSS;
if (priv->rx_conf & RTL818X_RX_CONF_MULTICAST)
*total_flags |= FIF_ALLMULTI;
rtl818x_iowrite32_async(priv, &priv->map->RX_CONF, priv->rx_conf);
}
I believe the card needs to receive multicast data in orde to pick up
RAs, and this seems to be properly set up by setting the
RTL818X_RX_CONF_MULTICAST flag. In fact, I have verified that this
actually gets set in my case, by printk()'ing "multicast" and
verifying that it is indeed > 0, as well as by changing the code to do
priv->rx_conf |= RTL818X_RX_CONF_MULTICAST;
unconditionally. Sadly, that didn't help. I also, just out of
cluelessness, fiddled with the RTL818X_RX_CONF_BROADCAST flag which is
not touched in this function, but only set once in rtl8187_start(),
but of course, that didn't make a difference either.
Only one thing seemed to work: Unconditionally putting the card into
monitor mode, by adding
priv->rx_conf |= RTL818X_RX_CONF_MONITOR;
somewhere before the iowrite in the function above. That did in fact
make a difference and my card picked up an RA and IPv6 address.
However, it's probably not really a fix, as having the card run in
monitor mode all the time doesn't sound like too good of an idea.
So ... I have the feeling that the whole multicast filtering stuff of
the card / driver doesn't seem to be working right. And I have no idea
if it's the hardware or the driver. I did indeed find some datasheet
for the card on the web, but either it didn't really contain the info
on how to do this stuff right (or, at all), or I was too stupid to
find / understand it.
I'd really appreciate it if someone has some help or pointers, as I'd
be really glad if I could find a proper way to fix this!
Greetings
Nils