[RFC 0/2] BCM283x Camera Receiver driver

[Dave Stevenson]

On 30 August 2017 at 11:45, Hans Verkuil <hverkuil at xs4all.nl> wrote:
> On 30/08/17 11:40, Dave Stevenson wrote:
>> Hi Hans.
>>
>> On 28 August 2017 at 15:15, Hans Verkuil <hverkuil at xs4all.nl> wrote:
>>> Hi Dave,
>>>
>>> What is the status of this work? I ask because I tried to use this driver
>>> plus my tc358743 on my rpi-2b without any luck. Specifically the tc358843
>>> isn't able to read from the i2c bus.
>>
>> I was on other things until last week, but will try to get a V2 sorted
>> either this week or early next.
>> The world moved on slightly too, so there are a few more updates
>> around fwnode stuff that I ought to adopt.
>>
>>> This is probably a bug in my dts, if you have a tree somewhere containing
>>> a working dts for this, then that would be very helpful.
>>
>> Almost certainly just pin ctrl on the I2C bus. The default for i2c0 is
>> normally to GPIOs 0&1 as that is exposed on the 40 pin header
>> (physical pins 27&28). The camera is on GPIOs 28&29 (alt0) for the
>> majority of Pi models (not the Pi3, or the early model B).
>
> Yep, that was the culprit!

Great. I like easy ones :-)

> I now see the tc, but streaming doesn't work yet. I'm not getting any
> interrupts in the unicam driver.

What resolution were you streaming at? There are a couple of things
that come to mind and I don't have solutions for yet.
Firstly the TC358743 driver assumes that all 4 CSI lanes are
available, whilst the Pi only has 2 lanes exposed. IIRC 1080P30 RGB
just trickles over into wanting 3 lanes with the default link
frequencies and you indeed don't get anything if one or more lane is
physically not connected.
Secondly was the FIFOCTL register set via state->pdata.fifo_level that
we discussed before. The default is 16, which is too small for some of
the smaller resolutions. 300 seems reasonable. You do get frames in
that situation, but they're generally corrupt.
I'm intending to try and make the TC358743 more flexible than just
accepting >720P, and if I can support multiple link frequencies then
so much the better as 1080P50 UYVY should be just possible on 2 lane,
however the lower resolutions are unlikely to work due to FIFO
underflow.

> BTW, when s_dv_timings is called, then you need to update the v4l2_format
> as well to the new width and height. I noticed that that didn't happen.

Yes, that came up in the previous discussions and is already fixed.

> Anyway, this is good enough for me for now since I want to add CEC support
> to the tc driver, and I do not need streaming for that...

That sounds fun.
  Dave