Message-ID: <4E81F8C8.4010909@lwfinger.net> (sfid-20110927_182447_392749_6FDED2B4)
Date: Tue, 27 Sep 2011 11:24:40 -0500
From: Larry Finger <Larry.Finger@lwfinger.net>
MIME-Version: 1.0
To: Ian Jeffray <ian@emobix.co.uk>
CC: linux-wireless@vger.kernel.org
Subject: Re: r8712u driver - on ARM
References: <4E81ED65.7060703@emobix.co.uk>
In-Reply-To: <4E81ED65.7060703@emobix.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Sender: linux-wireless-owner@vger.kernel.org

On 09/27/2011 10:36 AM, Ian Jeffray wrote:
> Dear all,
>
> I'm attempting to get some sense from a Realtek 8191S device on
> ARM linux. Using the latest kernel/drivers (3.0.4) I've had
> great success on x86 linux, achieving 94Mbit throughput.
>
> On ARM linux, however, the device is barely working. I can
> bring up the firmware (using the 20110818 firmware package):
>
> usb 1-1: new high speed USB device using musb-hdrc and address 2
> usb 1-1: New USB device found, idVendor=0bda, idProduct=8172
> usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> usb 1-1: Product: RTL8191S WLAN Adapter
> usb 1-1: Manufacturer: Manufacturer Realtek
> usb 1-1: SerialNumber: 00e04c000001
> r8712u: DriverVersion: v7_0.20100831
> r8712u: register rtl8712_netdev_ops to netdev_ops
> r8712u: USB_SPEED_HIGH with 4 endpoints
> r8712u: Boot from EFUSE: Autoload OK
> r8712u: CustomerID = 0x0000
> r8712u: MAC Address from efuse = 00:02:72:a7:12:47
>
> # ifconfig wlan0 up
> r8712u: Loading firmware from "rtlwifi/rtl8712u.bin"
> r8712u: 1 RCR=0x153f00e
> r8712u: 2 RCR=0x553f00e
>
> I then attempt some basic operations such as an SSID scan.
> At this point, I occasionally get a result, but more often than not,
> I get no results at all. There are 7 access points around me, so
> it's surprising to get nothing.

That is what one might expect if the probe messages for the scan are not being 
sent, and you are ending up with effectively a passive scan.

> Attempting to forcibly connect to anything is also fruitless.
>
> My host is a TI DaVinci DM8168 (OMAP3+toys). The USB host is not
> fantastic, but has been thrashed heavily with other devices and seems
> to be reliable in those cases.
>
> I'd appreciate any input and guidance as to what may be the issue here.
> There doesn't appear to be a great deal of debug info to be enabled in
> the driver, so I'm not sure what more I can add at this point to aid
> with resolving the problem. I fear some long days of pain trying to
> track down differences in operation for this device between ARM and x86.
>
> Could I ask if anyone can actually confirm (or deny) this particular
> driver/chipset works with an ARM host?

I have not tried this chip on an ARM host as I have no hardware. My testing has 
been with X86 and PPC - thus I know the endianess is OK, but that is the extent 
of my platform testing.

The first thing I would try is wireshark on another host to verify that packets 
are actually getting on the air.

Larry