This chip is the main USB control/demux in some cheap DVB-T USB devices currently available, such as:
- The WandTV
- The Elements High Definition DVB-T Receiver Model no DK-5203.
- Dongles with USB ID 15a4:9016 (or 15a4:9015 ?), such as the A-Link DTU (m)
- Geniatech T328B
However, the chip is fairly complex and supports a wide variety of device configurations (single USB, dual USB, Platform mode, PCI/PCIe based devices, and even SPI is supported by it with some tuners (such as for a Consumer Electronics product that runs Windows CE)).
Documentation for the AF901x can be obtained from AFA (under NDA), but it is apparently confusing, as well as incomplete -- as there are a lot of areas that are undocumented.
At present there are three different drivers Linux drivers available for the AF901x. That may strike one as being strange or showing signs of a state of dis-coordination, but in actuality, each driver has its own reason for being, and collectively they highlight the relative complexity of the chip and the flexibility in device design that its usage permits.
Opensource Mercurial Repositories
- http://jusst.de/hg/af901x ... This is a second driver attempt for the AF901x by Manu Abrahams. In his personal assessment, he got many things right, but some things are still wrong. In addition, his driver works with just one particular device
- http://linuxtv.org/hg/~anttip/af9015/ (Supported tuners are: MT2060, MT2061 and QT1010.) ... This is a reverse engineered driver, by Antti Palosaari, that is specific to the AF9015 chip alone, and for device's with a "MASTER based configuration" ... this driver was largely based upon and adapted from a leaked vendor released driver (discussed below)
Vendor Released Driver
- A vendor-written driver specific to the AF9015 chip alone is available from http://af.zsolttech.com/. Apparently, AFA had this driver written (authour, Rick Huang?) specifically for a single device from one customer, who then in turn ended up violating the NDA. (It was from that leaked driver that Antti was able to largely base/ and derive his RE attempts; see above discussion).
For devices based on the MT2060 tuner (such as the Geniatech T328B) you may need to patch the file MT2060M.h in the following way:
typedef unsigned long UData_t;
typedef unsigned int UData_t;
Then compile, install, modprobe dvb_usb_af9015 and you are finished.
A Comprehensive OSS Driver
For its part, Afatech does not want any of the above driver attempts to make their way into the kernel, as none of them are very robust in terms of chip support.
Instead, AFA has embarked upon the development of yet another OSS driver, which will be generic in that it will be capable of supporting the entire AF901x family as well as all possible device configurations permitted. In addition to the expectation that it will be this driver that is eventually adopted into the kernel, AFA have also signaled that they intend provide continuous support (i.e. they will stay on as the driver's maintainer).
Currently, this newest driver has reached a second round of testing in AFA labs, but that has only been in conjunction (with some peripheral manufacturers) with a few devices, and, as it stands, the code is still not particularly generic (due to both the complexities of the chip itself as well as those involved in getting the various device configurations to work). So, as of yet, there currently isn't anything for the end user to test. However, as soon things progress past this stage, there will be something released for users to test. There is no specific release timeframe set for this, but hopefully it will be soon, as the chip manufacturer (as well as everybody else involved) is under pressure, due to the large adoption of the chip by different peripheral manufacturers (Avermedia, Terratec, Azurewave, DigitalNow, Pinnacle, as well as some number of unbranded Chinese manufacturers too). In short, a lot more devices based on this chipset are expected to materialize.
Driver Development Log
I'm currently writing a driver for this chip, and as there's not much around in terms of a howto on this subject, I thought it might be worth documenting the process.
I've got a head start in that there is an earlier chip from Afatech, the AF9005, for which drivers were recently written/developed. I've got the driver source code for that chip along with the documentation for that and my chip, so I'm going to be working on modifying the AF9005 drivers to work with the AF9015. I'm not sure if I'm allowed to post the documentations here, I'll find out and if so a link will be posted.
To start with, there are some great Linux USB tutorials on Linux Journal:
- start here: How to Write a Linux USB Device Driver
- then here: Writing a Simple USB Driver
- Hot Plug
- and then: Snooping the USB Data Stream
Also get the source for V4L-DVB:
You will find the usb drivers are in ./v4l-dvb/linux/drivers/media/dvb/dvb-usb. Have a bit of a browse through them while you're reading through the first article above, get a feel for how the driver is put together. (There is a procedure described in http://www.ubuntuforums.org/showthread.php?p=1067326).