2011-09-30 13:28:33     Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

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2011-09-30 13:28:33     Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Ian Jeffray (UNITED KINGDOM)

Message: 103660   

 

I'm trying to get a device with the Realtek RTL8191SU wifi chip working with a BF527 Blackfin board.   I've tried the driver that's in 'staging' in recent kernels, and the canonical original source package provided on realtek.com -- this is the r8712u driver (yes, 8712 driver for 8191 chipset, that's right).

 

This driver and chipset has proved good and stable on an x86 linux machine, achieving 94Mbit/sec which seems pretty decent for a single transmitter 802.11n device.    I've achieved 42Mbit/sec on an old 400Mhz ARM9 S3C board too.

 

The driver *appears* to be ok when compiled for Blackfin, but the device - the firmware upload appears to be successful and the device's LEDs flash as expected -- but I'm seeing no actual wifi traffic during a 'iwlist wlan0 scanning' action, or when using wpa_supplicant.

 

The MUSB on this (custom) BF527 board has proved very reliable when connecting to things like memory stick devices - giving me around 10MB/sec throughput, so I do believe that in essence the USB is working.

 

So - I'd like to know if others have tried this driver/chipset on Blackfin, and what the experiences were.

 

Alternatively, if anyone has better suggestions for decent performance 802.11n USB devices, I'd love to hear.   I've purchased and tested many different chipsets and even on x86 or ARM, only the Realtek was truly reliable.   I'm so disappointed it's not working with a Blackfin at all.

 

TIA,

 

Ian.

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2011-10-03 11:00:51     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Stuart Henderson (UNITED KINGDOM)

Message: 103698   

 

Hi Ian,

 

I'm afraid i've not got any experience with the wifi chip you mention.  Our application engineers may be able to provide some information to get you going, however they are currently unavailable due to a national holiday and won't be back until next Monday.

 

In the meantime, if you could let us know which version/revision of the toolchain and kernel/uclinux you are using, this may help guide the engineers on their return.

 

Stu

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2011-10-04 15:50:42     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Ian Jeffray (UNITED KINGDOM)

Message: 103708   

 

Hi Stuart,

 

An Edinburgh reply? Cool. I actually work across the hall from ADI in Glasgow - but never actually see anyone in there.

 

Anyhow - I've tried the '2010R1' release kernel, and also the nightly 3.0.0 kernel builds from uclinux.org (which has the rt8172u driver in 'staging' - same code essentially though), both with the latest release toolchain.  No dice.  I've had the rtl8172u driver maintainer attempt to help, and tested several ideas, but we've drawn a blank.   The driver doesn't appear to be doing anything special or odd, and does work well on x86, PPC and S3C ARM targets.

 

The problem does appear to be specific to musb, rather than Blackfin, as I've also got real problems with this device on a TI Sitara device with the musb host (albeit different DMA).   Going to try a TI OMAP3 (Beagleboard-xM) tomorrow which I believe is the same DMA as Blackfin.

 

Bar the annoying lack of hub support, I always thought the musb host in the BF527 was pretty solid - seems that it's tripping up here somehow.

 

Will keep hacking away at it.   It'd be nice to get a half decent 802.11n solution working for Blackfin.

 

Ian.

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2011-10-10 03:42:15     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Sonic Zhang (CHINA)

Message: 103769   

 

How do you see no actual wifi traffic? Could you insert a USB analyzor between MUSB and RTL8191SU? What does the log look like?

 

Btw, if you want to compile the trunk 3.0 kernel source, please also use the 2011R1-RC2 toolchain .

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2011-10-13 05:24:27     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Martin Strubel (SWITZERLAND)

Message: 103844   

 

Hi Ian,

 

I don't know if this helps, but I have made good experience with the Atheros chipset a while ago. The USB stick(s) I've got is TP-821N from Tplink. It was actually the only one of those I tried which achieved decent data rates (effective ~105 Mbit/s). However, I had to patch in some external code into the uClinux code to make it work at full speed, I don't exactly remember that, would have to dig that up, I think I got the detailed tips'n'tricks from a german forum (www.mikrocontroller.net).

 

Another issue that got into my mind: The OTG implementation on some eval boards may also cause trouble, I've had issues with some adapters that would pull a lot of power when plugged in. What turned out (by scoping on the pins of my BF527 ezkit): The capacitor wasn't strong enough to supply the current drawn on plug in, so there was a small glitch down to 4.7 volts, which obviously kept the stick from fully booting up. But you should then - at least in most cases - see USB error messages in the 'dmesg' output later on when communicating with the stick.

 

Greetings,

 

- Martin

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2011-10-15 12:47:06     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Ian Jeffray (UNITED KINGDOM)

Message: 103877   

 

Hi Sonic,  Thanks for the response.

 

> How do you see no actual wifi traffic? Could you insert a USB analyzor between MUSB and RTL8191SU? What does the log look like?

 

I don't have a hardware USB analyser, but I tried using the kernel logging and saw it was failing there.  it seems no packets appear from the host to the driver.   I tried saving some logs from an x86 host when the driver is working fine there but there's so much stuff I can't begin to make sense of it.

 

 

 

> Btw, if you want to compile the trunk 3.0 kernel source, please also use the 2011R1-RC2 toolchain .

 

I can't see any release called that, but the 2010-RC4 seems to be fine.  I'll try again with the nightly snapshot tools just for the heck of it though :-)    Is there something specific you're aware of which would be an issue with the old tools, because I've seen no problems with anything other than this wireless stuff.

 

Thanks again

 

Ian

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2011-10-15 12:51:11     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Ian Jeffray (UNITED KINGDOM)

Message: 103878   

 

Hi Martin, very nice to hear from you.

 

Thanks for the suggestion.  I bought one of these devices based on your suggestion (it's actually a 'v2' device) - it uses the carl9170 driver in the latest 3.0 kernel.  It works, with some occasional stalls, but the best I've had from it is 16Mbps.

 

Regarding USB power - a great suggestion - I carefully checked the USB host power on our custom host board.  It never dips at all.  The wifi dongle only pulls 160mA at most.  I also tried feeding VBUS from a good lab supply and saw no change in operation.

 

I shall try to dig around on mikrocontroller.net for the extra hints to see if I can get some performance!

 

Thanks again,

 

Ian.

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2011-10-17 02:37:53     Re: Realtek RTL8191SU 802.11n wifi with Blackfin BF527 MUSB

Sonic Zhang (CHINA)

Message: 103890   

 

2011R1-RC2 toolchain is here.

 

  blackfin.uclinux.org/gf/project/toolchain/frs/?action=FrsReleaseBrowse&frs_package_id=74

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