Re: I: RTL8187 driver in linux 3.4

Re: I: RTL8187 driver in linux 3.4

[Larry Finger]

On 06/01/2012 09:50 AM, Jacopo Runchi wrote:
> Thank you for the help on the request below.
>
> Bye, Jacopo.
>
> *Da:*Jacopo Runchi [mailto:jacoporunchi@hotmail.it]
> *Inviato:* venerdì 1 giugno 2012 15:21
> *A:* 'herton@canonical.com'; 'htl10@users.sourceforge.net';
> 'Larry.Finger@lwfinger.net'
> *Oggetto:* RTL8187 driver in linux 3.4
>
> Hi, I write to you because I found you are the maintainers of the driver in subject.
>
> Hi, I’m working with a USB device using chipset RTL8187 connected to a mips
> router with Openwrt.
>
> With the old driver r8187l.ko in linux 2.4.x it works fine.
>
> With the RTL8187 driver, if the signal is not good enough, it can establish a
> connection, but it doesn’t transfer datas (no ping for example).
>
> I think it is a bug of the driver, so I would like to know if you know this bug
> and if you have planned to solve it…
>
> There is any change planned on this driver?
>
> I hope for a generous answer and I’m sorry for my bad English.

The address looks OK to me. I do not know why it bounced.

My involvement with the RTL8187 devices only started with 2.6.X, where X is 25 
or 26. I have no knowledge of the driver in kernel 2.4.

There have been various complaints about the driver, particularly on RTL8187L 
hardware, that concern rate setting using the minstrel algorithm. I have been 
unable to reproduce the results.

Please answer the following questions;

Does the device work is you lock the rate at 1 Mbps?

What is the USB ID as shown by lsusb?

Does it work when you use the PID rate-setting algorithm? To enable this, you 
will need to set CONFIG_EXPERT=y.

Larry


Does it work better if you choose

Re: R: I: RTL8187 driver in linux 3.4

[Larry Finger]

On 06/01/2012 11:45 AM, Jacopo Runchi wrote:
> Hi, thanks for your answer.
>> From what I was able to understand, the old driver uses the ieee8011 stack,
> and the new uses the mac80211.
> Since I'm neither a newbie, nor an expert, I don't know if the sentence has
> a real meaning...
>
> The try about the rate has already been tested. No changes locking it. Same
> results with the automatic rate, with rate 1 mbps and with 54 mbps...
> Maybe I can send you the device id in lsusb, this evening or during the next
> days, since now I flashed the old 2.4 release and I need to reflash the
> device with the new kernel.
 >
> For what concern the "PID rate-setting algorithm" setting "CONFIG_EXPERT=y"
> I don't know anything...
> I'm going to search for it on the net and I will try it too.

Is lsusb not available in the 2.4 system?

DO NOT DROP the wireless list from the Cc. Doing so converts the exchange back 
to a private one, and I will ignore further messages if you do that. It is also 
better if you bottom post. That way a reader can go through the background material.

The 2.4 driver used its own built-in softmac 802.11 stack. Mac80211 is a 
replacement for it. Although mac80211 has a great deal more functionality, they 
generally do the same things.

Larry

Re: I: RTL8187 driver in linux 3.4

[Larry Finger]

On 06/01/2012 04:36 PM, Jacopo Runchi wrote:
> Hi, i'm using Openwrt on the device, so lsusb is not available.
> The USB device used is an ALFA NETWORK AWUS036H.
> In the last try i set the rate fixed, but the iwlist command says "unknown bitrate".
>
> So, I'm unable to verify that the rate has been successfully set.
> In fact also setting the rate fixed to 1M it doesn't works anymore.
> The behaviour seems to be the same as this post:
> http://www.gossamer-threads.com/lists/linux/kernel/860544 .
>
> I found some infos on what is the pid rate control algorithm, but I didn't
> understand how to set it or how to verify how is it set.
> Do I have to recompile the kernel to do it?

The AWUS036H is an RTL8187L. You don't need to send me the lsusb output.

Yes, to enable PID, you will need to reconfigure and recompile the kernel.

I have an AWUS036H, and got the following:

finger@linux-y7cb:~/wireless-testing> iwconfig
wlan0     IEEE 802.11bg  ESSID:"lwfdjf-n"
           Mode:Managed  Frequency:2.422 GHz  Access Point: C0:3F:0E:BE:2B:44
           Bit Rate=36 Mb/s   Tx-Power=0 dBm
           Retry  long limit:7   RTS thr:off   Fragment thr:off
           Power Management:off
           Link Quality=70/70  Signal level=-26 dBm
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:22   Missed beacon:0

finger@linux-y7cb:~/wireless-testing> sudo iwconfig wlan0 rate 1M
finger@linux-y7cb:~/wireless-testing> iwconfig
wlan0     IEEE 802.11bg  ESSID:"lwfdjf-n"
           Mode:Managed  Frequency:2.422 GHz  Access Point: C0:3F:0E:BE:2B:44
           Bit Rate=1 Mb/s   Tx-Power=0 dBm
           Retry  long limit:7   RTS thr:off   Fragment thr:off
           Power Management:off
           Link Quality=70/70  Signal level=-30 dBm
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:29   Missed beacon:0

finger@linux-y7cb:~/wireless-testing> ping -c5 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=4.34 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=3.24 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=2.61 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=3.14 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=64 time=2.36 ms

--- 192.168.1.1 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4006ms
rtt min/avg/max/mdev = 2.368/3.144/4.348/0.684 ms


By removing the antenna, I could reduce the signal strength reported by iwconfig 
to -63 dBm, and still connect and ping with the tayr set at 1 Mbps.

wlan0     IEEE 802.11bg  ESSID:"Larry_wpa1"
           Mode:Managed  Frequency:2.462 GHz  Access Point: 00:1A:70:46:BA:B1
           Bit Rate=1 Mb/s   Tx-Power=0 dBm
           Retry  long limit:7   RTS thr:off   Fragment thr:off
           Power Management:off
           Link Quality=47/70  Signal level=-63 dBm
           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
           Tx excessive retries:0  Invalid misc:117   Missed beacon:0

finger@linux-y7cb:~/wireless-testing> ping -c5 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=63 time=4.35 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=63 time=3.73 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=63 time=3.73 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=63 time=3.88 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=63 time=6.87 ms

When I reset the rate to "auto", the driver set it to 54M, and it would not 
communicate.

Larry

Re: I: RTL8187 driver in linux 3.4

[Larry Finger]

On 06/02/2012 03:14 AM, Jacopo Runchi wrote:
> So the problem is the same as you reported.
>
> So is there either a bug related to the algorithm who manages the rate, or
> should I change something related to the algorithm?
> I searched for the CONFIG_EXPERT=y setting and for the pid rate algorithm
> setting, but I've not found anything at all.

The parameter is in the kernel configuration file ".config". You need to change 
it with "make menuconfig ARCH=xxxx". Once you set EXPERT to "y", then the PID 
setting will be available in the Network => Wireless settings.

> For it can be ok. Have you planned to do something to correct this at
> driver-kernel level, to work with default "auto" rate?

It is a driver problem, but I do not know how soon it will be fixed. At the 
moment, I have more pressing concerns. Now that I can reproduce it, the fix will 
be easier to find.

Larry