Re: TW686x Linux Main Line Driver Issue

[Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>]

On 20 April 2017 at 07:10, Anuradha Ranasinghe <anuradha@tengriaero.com> wrote:
> Dear All,
>
> This issue is associated to the Linux Mainline Kernel 4.1.15.2 (branch2)
> tw686x upstream driver and IMX6Q platform.
>
> We have an analog camera capture board (a custom one) based around tw6865.
> We are interfacing it with Nitrogen6_Max board (IMX6Q) . We use the
> aforementioned kernel with the boundary devices latest patches to the tw686x
> driver (having 3 DMA buffers) and system running on Ubuntu 16 Xenial Mate
> version.
> https://github.com/boundarydevices/linux-imx6/commits/7fcd22da6d731b36e5ab856551c41301fca9881f
>
> The driver initialization, device and composite signal detection work well
> as intended. But when the streaming started, frame rate becomes lower and
> after few frames, the whole system freezes. To get the camera to work to
> this level, we had to do :
>

What dma-mode are you using? Have you tried other dma-modes?

How many frames do you manage to obtain? I believe you should
debug this further and provide more information.

> 1. Disable PCI interrupts from the kernel (from menuconfig and pci=nomsi
> kernel command)

(CCing PCI people) Lucas, Richard: any idea about why is this parameter needed?

> 2. Set Coherent_Pool to 128M in boot args to get the memory allocation for
> driver. Without this driver does not enumerate.
>

Hm.. interesting.

> I can confirm that there is no issue in our hardware. I strictly followed
> the free scale data sheet recommendations. So I have few questions needing
> your answers :
>
>> Have you guys tried this driver for tw6865 or a related chip on same root
>> fs ? If not can you kindly mention the operating condition you had ?

FWIW, I have tested tw6869 on x86_64. It works well here, but only
using dma-mode=memcpy, as documented here:

http://lxr.free-electrons.com/source/drivers/media/pci/tw686x/tw686x-core.c#L19

>> Is attached patch required for higher kernel versions (4.1.15) to support
>> DMA accessing ?

I have no idea about that patch. The patch has nothing to do with tw686x,
but it's i.MX6 platform-specific, you should ask the author.

>> Is there any additional settings (cma allocation, memory mapping) required
>> for this newer kernel ?

That depends on your platform and usage.

>> I use the pipeline :
> gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,width=720,height=480
> ! autovideosink
> for an unknown reason, imxv4l2videosrc does not work at all for this pcie
> camera.
>

You need to ask imxv4l2videosrc's authors.

-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar