| Message ID | 1270804497-16001-2-git-send-email-colin.king@canonical.com |
|---|---|
| State | Accepted |
| Delegated to: | Stefan Bader |
| Headers | show |
On Fri, Apr 09, 2010 at 10:14:57AM +0100, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > BugLink: https://bugs.launchpad.net/bugs/557239 > > The range of signal strength reported by rt2x00 is very narrow and > the base offset is too low. The original algorithm was based on a > mix of 20% from the RSSI, 40% from RX quality and 40% from TX > quality metrics. > > For the rt73usb driver, the TX failure metric is a piece of fiction > and always returns success (unless there is a USB URB failure) so > this skews the TX quality metrics and hence skews the signal > strength result. > > The original calculation is only really useful for a network > that you're already connected to. The reliance on RX and TX > quality metrics when not connected to a network skews the final > signal strength since the only valid metric (RSSI) is a minor > contributor to the final calculation. > > A survey of most wifi drivers show that using just the RSSI is > a common method of producing a signal strength metric, so this > fix adjusts the wifi strength to be calculated just on RSSI. > > This fix also adjusts the range of the DEFAULT_RSSI_OFFSET to > correctly reflect the absolute maximum range of the RSSI. The > original code was a little overzealous in providing enough > headroom. > > Signed-off-by: Colin Ian King <colin.king@canonical.com> > --- > .../drivers/net/wireless/rt2x00/rt2x00.h | 6 +++--- > .../drivers/net/wireless/rt2x00/rt73usb.h | 2 +- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > index 311b8d0..97812c8 100644 > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > @@ -196,9 +196,9 @@ struct link_qual { > int tx_percentage; > int tx_success; > int tx_failed; > -#define WEIGHT_RSSI 20 > -#define WEIGHT_RX 40 > -#define WEIGHT_TX 40 > +#define WEIGHT_RSSI 100 > +#define WEIGHT_RX 0 > +#define WEIGHT_TX 0 > }; > > /* > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > index 60f98be..97f9503 100644 > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > @@ -39,7 +39,7 @@ > * Signal information. > * Defaul offset is required for RSSI <-> dBm conversion. > */ > -#define DEFAULT_RSSI_OFFSET 120 > +#define DEFAULT_RSSI_OFFSET 104 > > /* > * Register layout information. Looks to do what you claim. I am assuming you are measureing against other cards in the same environ and with these patches have a similar metrics. So: Acked-by: Andy Whitcroft <apw@canonical.com> -apw
On Fri, 2010-04-09 at 15:14 +0100, Andy Whitcroft wrote: > On Fri, Apr 09, 2010 at 10:14:57AM +0100, Colin King wrote: > > From: Colin Ian King <colin.king@canonical.com> > > > > BugLink: https://bugs.launchpad.net/bugs/557239 > > > > The range of signal strength reported by rt2x00 is very narrow and > > the base offset is too low. The original algorithm was based on a > > mix of 20% from the RSSI, 40% from RX quality and 40% from TX > > quality metrics. > > > > For the rt73usb driver, the TX failure metric is a piece of fiction > > and always returns success (unless there is a USB URB failure) so > > this skews the TX quality metrics and hence skews the signal > > strength result. > > > > The original calculation is only really useful for a network > > that you're already connected to. The reliance on RX and TX > > quality metrics when not connected to a network skews the final > > signal strength since the only valid metric (RSSI) is a minor > > contributor to the final calculation. > > > > A survey of most wifi drivers show that using just the RSSI is > > a common method of producing a signal strength metric, so this > > fix adjusts the wifi strength to be calculated just on RSSI. > > > > This fix also adjusts the range of the DEFAULT_RSSI_OFFSET to > > correctly reflect the absolute maximum range of the RSSI. The > > original code was a little overzealous in providing enough > > headroom. > > > > Signed-off-by: Colin Ian King <colin.king@canonical.com> > > --- > > .../drivers/net/wireless/rt2x00/rt2x00.h | 6 +++--- > > .../drivers/net/wireless/rt2x00/rt73usb.h | 2 +- > > 2 files changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > > index 311b8d0..97812c8 100644 > > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > > @@ -196,9 +196,9 @@ struct link_qual { > > int tx_percentage; > > int tx_success; > > int tx_failed; > > -#define WEIGHT_RSSI 20 > > -#define WEIGHT_RX 40 > > -#define WEIGHT_TX 40 > > +#define WEIGHT_RSSI 100 > > +#define WEIGHT_RX 0 > > +#define WEIGHT_TX 0 > > }; > > > > /* > > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > > index 60f98be..97f9503 100644 > > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > > @@ -39,7 +39,7 @@ > > * Signal information. > > * Defaul offset is required for RSSI <-> dBm conversion. > > */ > > -#define DEFAULT_RSSI_OFFSET 120 > > +#define DEFAULT_RSSI_OFFSET 104 > > > > /* > > * Register layout information. > > Looks to do what you claim. I am assuming you are measureing against > other cards in the same environ and with these patches have a similar > metrics. Indeed. It's a rather subjective to say the least. I surveyed a bunch of drivers and summarised my findings here: http://smackerelofopinion.blogspot.com/2010/02/examining-wifi-signal-quality.html > So: > > Acked-by: Andy Whitcroft <apw@canonical.com> > > -apw
It sounds like you tested well. HAve you sent it upstream as well or is it not applicable there? In general it seems to be doing what you claim... Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > BugLink: https://bugs.launchpad.net/bugs/557239 > > The range of signal strength reported by rt2x00 is very narrow and > the base offset is too low. The original algorithm was based on a > mix of 20% from the RSSI, 40% from RX quality and 40% from TX > quality metrics. > > For the rt73usb driver, the TX failure metric is a piece of fiction > and always returns success (unless there is a USB URB failure) so > this skews the TX quality metrics and hence skews the signal > strength result. > > The original calculation is only really useful for a network > that you're already connected to. The reliance on RX and TX > quality metrics when not connected to a network skews the final > signal strength since the only valid metric (RSSI) is a minor > contributor to the final calculation. > > A survey of most wifi drivers show that using just the RSSI is > a common method of producing a signal strength metric, so this > fix adjusts the wifi strength to be calculated just on RSSI. > > This fix also adjusts the range of the DEFAULT_RSSI_OFFSET to > correctly reflect the absolute maximum range of the RSSI. The > original code was a little overzealous in providing enough > headroom. > > Signed-off-by: Colin Ian King <colin.king@canonical.com> Acked-by: Stefan Bader <stefan.bader@canonical.com> > --- > .../drivers/net/wireless/rt2x00/rt2x00.h | 6 +++--- > .../drivers/net/wireless/rt2x00/rt73usb.h | 2 +- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > index 311b8d0..97812c8 100644 > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h > @@ -196,9 +196,9 @@ struct link_qual { > int tx_percentage; > int tx_success; > int tx_failed; > -#define WEIGHT_RSSI 20 > -#define WEIGHT_RX 40 > -#define WEIGHT_TX 40 > +#define WEIGHT_RSSI 100 > +#define WEIGHT_RX 0 > +#define WEIGHT_TX 0 > }; > > /* > diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > index 60f98be..97f9503 100644 > --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h > @@ -39,7 +39,7 @@ > * Signal information. > * Defaul offset is required for RSSI <-> dBm conversion. > */ > -#define DEFAULT_RSSI_OFFSET 120 > +#define DEFAULT_RSSI_OFFSET 104 > > /* > * Register layout information.
diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h index 311b8d0..97812c8 100644 --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt2x00.h @@ -196,9 +196,9 @@ struct link_qual { int tx_percentage; int tx_success; int tx_failed; -#define WEIGHT_RSSI 20 -#define WEIGHT_RX 40 -#define WEIGHT_TX 40 +#define WEIGHT_RSSI 100 +#define WEIGHT_RX 0 +#define WEIGHT_TX 0 }; /* diff --git a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h index 60f98be..97f9503 100644 --- a/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h +++ b/updates/compat-wireless-2.6/drivers/net/wireless/rt2x00/rt73usb.h @@ -39,7 +39,7 @@ * Signal information. * Defaul offset is required for RSSI <-> dBm conversion. */ -#define DEFAULT_RSSI_OFFSET 120 +#define DEFAULT_RSSI_OFFSET 104 /* * Register layout information.