Category Archives: Hardware

TBS 6281 Tuner Card fails after a few days: Solved!

The biggest issue I’ve had with my new Myth build is that after a few days all recordings would fail. There wasn’t much evidence in the mythbackend logs. All I got was something like this when trying to record:

Aug 28 10:40:18 ripley mythbackend: mythbackend[10907]: E DVBRead mpeg/mpegstreamdata.cpp:365 (AssemblePSIP) MPEGStream[3](0x7fcde016faa8): Error: offset>181, pes length & current cannot be queried

In the end, it turned out that the clue was the following crash shown in /var/log/syslog:

Aug 23 07:46:24 ripley kernel: [385041.373970] irq 17: nobody cared (try booting with the "irqpoll" option)
Aug 23 07:46:24 ripley kernel: [385041.373975] CPU: 0 PID: 0 Comm: swapper/0 Tainted: PF IO 3.13.0-30-generic #55-Ubuntu
Aug 23 07:46:24 ripley kernel: [385041.373977] Hardware name: Gigabyte Technology Co., Ltd. B85M-HD3/B85M-HD3, BIOS F7 03/11/2014
Aug 23 07:46:24 ripley kernel: [385041.373978] ffff88022f24a29c ffff88023e203e68 ffffffff8171a324 ffff88022f24a200
Aug 23 07:46:24 ripley kernel: [385041.373981] ffff88023e203e90 ffffffff810c19e2 ffff88022f24a200 0000000000000011
Aug 23 07:46:24 ripley kernel: [385041.373984] 0000000000000000 ffff88023e203ed0 ffffffff810c1e7c 000000003e203eb0
Aug 23 07:46:24 ripley kernel: [385041.373986] Call Trace:
Aug 23 07:46:24 ripley kernel: [385041.373988] [] dump_stack+0x45/0x56
Aug 23 07:46:24 ripley kernel: [385041.373997] [] __report_bad_irq+0x32/0xd0
Aug 23 07:46:24 ripley kernel: [385041.373999] [] note_interrupt+0x1ac/0x200
Aug 23 07:46:24 ripley kernel: [385041.374001] [] handle_irq_event_percpu+0xd9/0x1d0
Aug 23 07:46:24 ripley kernel: [385041.374003] [] handle_irq_event+0x3d/0x60
Aug 23 07:46:24 ripley kernel: [385041.374005] [] handle_fasteoi_irq+0x5a/0x100
Aug 23 07:46:24 ripley kernel: [385041.374009] [] handle_irq+0x1e/0x30
Aug 23 07:46:24 ripley kernel: [385041.374012] [] do_IRQ+0x4d/0xc0
Aug 23 07:46:24 ripley kernel: [385041.374015] [] common_interrupt+0x6d/0x6d
Aug 23 07:46:24 ripley kernel: [385041.374016] [] ? cpuidle_enter_state+0x52/0xc0
Aug 23 07:46:24 ripley kernel: [385041.374021] [] cpuidle_idle_call+0xb9/0x1f0
Aug 23 07:46:24 ripley kernel: [385041.374024] [] arch_cpu_idle+0xe/0x30
Aug 23 07:46:24 ripley kernel: [385041.374026] [] cpu_startup_entry+0xc5/0x290
Aug 23 07:46:24 ripley kernel: [385041.374030] [] rest_init+0x77/0x80
Aug 23 07:46:24 ripley kernel: [385041.374033] [] start_kernel+0x438/0x443
Aug 23 07:46:24 ripley kernel: [385041.374036] [] ? repair_env_string+0x5c/0x5c
Aug 23 07:46:24 ripley kernel: [385041.374038] [] ? early_idt_handlers+0x120/0x120
Aug 23 07:46:24 ripley kernel: [385041.374040] [] x86_64_start_reservations+0x2a/0x2c
Aug 23 07:46:24 ripley kernel: [385041.374042] [] x86_64_start_kernel+0x143/0x152
Aug 23 07:46:24 ripley kernel: [385041.374043] handlers:
Aug 23 07:46:24 ripley kernel: [385041.374050] [] saa716x_tbs6281_pci_irq [saa716x_tbs_dvb]
Aug 23 07:46:24 ripley kernel: [385041.374051] Disabling IRQ #17

There was some kind of IRQ issue with the TBS card. I found the solution to the problem here:

http://www.tbsdtv.com/forum/viewtopic.php?f=52&t=7631#p24903

It turns out to be an incompatibility between my up-to-date motherboard and the legacy interrupts the TBS card uses by default. The solution is to instruct the TBS driver to use the new MSI interrupts, which is very easy to do. Just create the following file:

/etc/modprobe.d/tbs.conf

Containing the following:

options saa716x_tbs-dvb int_type=1

After a reboot, run this command to check that it’s worked, you should see “PCI-MSI-edge”:

cat /proc/interrupts | grep SAA
45: 134857 0 PCI-MSI-edge SAA716x Core

My system has been fine since I did the above, so I’m pretty sure it’s fixed it for me. It’s nice to have a fully working Myth box again!

MythTV PC Build

The bits for my new build, which is my 3rd MythTV box, arrived on Saturday. My first box was based on an Asus Pundit barebones chassis and was built ten years ago in 2004. A couple of years later I built a silent PC around a Scythe Ninja cooled Athlon CPU, which I’ve been using ever since.

The spec of the new one is posted below. I haven’t built a PC in years so it was great fun. Things haven’t changed that much and it screwed together very easily. In my view, the case is one of the most important factors when building your own PC. I admit that I did skimp on cost when selecting the Fractal Designs 1000 case, which appeared a bit flimsy in places when I opened the box. However, as I had hoped, the case is a triumph of design over budget and it’s very well thought out. It’s a small case, but still takes a full size ATX power supply. With a micro-ATX motherboard there’s still plenty of space inside. It helps that I didn’t bother with an optical drive, so any spare cables can be tucked up into the drive bays (I also saved some cash by not getting a modular PSU).

I intend to just velcro the tiny SSD in place and put the 2 big 3.5″ drives in the vertical bays.

The system powered up first time and into the new UEFI BIOS. Very snazzy. I was dying to move onto the Mythbuntu install but my Saturday night was taken up by a LAN party with my brothers, consisting of plenty of beer, Grid, Modern Warfare and Left 4 Dead. On Sunday night I was distracted by the World Cup final. Oh well, I’m sure I’ll get round to it eventually…

New MythTV Build

I’ve ordered the hardware for my new build!

MythTV is pretty versatile and can be tailored to meet your viewing needs. It consists of “backend” computers which do the recording and storage and “frontends” which do the playback. As the content can be shared using standard technologies such as DLNA, other devices can also be used to watch it, such as smart TVs, PS3s, smartphones, etc.

For my setup, I use a combined backend/frontend connected to my main TV. I find this to be the most complete way to run Myth, as everything can be done easily and cheaply. When I built my last system, the big concern was how quiet the PC was. Depending on the layout of your living room, it may be easy to hide even a large box. Alternatively, you could go for a stylish media centre case and have it on display. Or a tiny separate frontend. That’s the beauty of Myth – choices.

In my new house, I actually have the PC in the attached garage, connected to my TV through a hole in the wall! With this setup, I have no worries about how noisy or big or ugly the box is, and the living room is as neat as could be. My wife used to hate all the cables nested behind the TV gathering dust!

So, for my new build I decided to go for state of the art, but very generic hardware. When you try to do things pretty or quiet they start to get more expensive. So, with a budget of about £400 I just picked what seemed reasonable…

The design brief was a combined backend/frontend, dual tuner Freeview HD (DVB-S2), decent storage for videos. Connected to a TV over HDMI.

With HD playback required, the biggest question was what to do for the graphics. In the past, I have always gone for AMD CPUs and nVidia graphics. nVidia have always had the best support within Myth and HD works well. However, things change.

I am intrigued by the latest Intel kit, which has a combined CPU/GPU. There are open source drivers and excellent Linux compatibility. In theory, it sounds perfect. So, I will give it a try. Worst case, I can always stick an nVidia card in there!

CPU: Intel Pentium G3420 Dual Core
Intel’s 4th gen processor Haswell CPU for about £45. Should be super speedy and do the HD decoding using the in-build GPU. We will see.

Motherboard: Gigabyte B85M-HD3
Micro ATX, Socket 1150, USB3, SATA 600 and the right price. £45.

Memory: Corsair CMZ8GX3M2A1600C9 DDR3
I splashed out and went for 8GB of RAM. Probably overkill, but 4GB just didn’t seem enough on a modern PC. £60.

PSU: Corsair Builder Series CX 430W
Cheap and good quality power supply. Not modular, but the interior of this PC won’t be entering any beauty contests. £30

SSD: Corsair CSSD-F60GBLS
The disk for the Mythbuntu OS install will be a small (60GB) SSD for speed and reliability. All the content will be on a couple of big 3.5 inch disks. £40

HDD: Western Digital Green 2TB
I already have one of these from my old machine, so this one will make a pair. Did think of getting the WD Red but read that they are more intended for RAIDS and these are better for a second drive. £60

Case: Fractal Design Core 1000
Fairly small case with room for a full size PSU. Looks nice in the pictures and from a respectable company. Looking forward to seeing this. May be a little squashed with 3 drives in but there won’t be an optical drive so there should be just enough space. £30

Tuner: TBS TBS6280 PCI-E DVB-T2 Dual
2 tuners in a tiny footprint. This will replace the 2 Hauppauge cards I currently use (which don’t do HD). Linux support is good, even though the drive is proprietary. Only drawback is that the supplied remote is not supported. No big deal ads there are plenty of other nicer remotes on the market. £72

So, that lot should be winging its way to me from Amazon as we speak. Looking forward to putting it together…