Re: i.mx6 camera interface (CSI) and mainline kernel

[Hans Verkuil <hverkuil@xs4all.nl>]

On 03/10/2016 01:12 AM, Steve Longerbeam wrote:
> On 03/09/2016 02:44 PM, Tim Harvey wrote:
>> On Tue, Mar 8, 2016 at 6:06 PM, Steve Longerbeam
>> <steve_longerbeam@mentor.com> wrote:
>>> On 03/07/2016 08:19 AM, Tim Harvey wrote:
>> <snip>
>>>
>>> Hi Tim, good to hear it works for you on the Ventana boards.
>>>
>>> I've just pushed some more commits to the mx6-media-staging branch that
>>> get the drivers/media/i2c/adv7180.c subdev working with the imx6 capture
>>> backend. Images look perfect when switching to UYVY8_2X8 mbus code instead
>>> of YUYV8_2X8. But I'm holding off on that change because this subdev is used
>>> by Renesas targets and would likely corrupt captured images for those
>>> targets. But I believe UYVY is the correct transmit order according to the
>>> BT.656 standard.
>>>
>>> Another thing that should also be changed in drivers/media/i2c/adv7180.c
>>> is the field type. It should be V4L2_FIELD_SEQ_TB for NTSC and V4L2_FIELD_SEQ_BT
>>> for PAL.
>>>
>>> Steve
>>>
>>>
>> Steve,
>>
>> with your latest patches, I'm crashing with an null-pointer-deref in
>> adv7180_set_pad_format. What is your kernel config for
>> CONFIG_MEDIA_CONTROLLER and CONFIG_VIDEO_V4L2_SUBDEV_API?
> 
> Right, I thought I fixed that, I was passing a NULL pad_cfg for
> TRY_FORMAT, but that was fixed. Maybe you fetched a version
> of mx6-media-staging while I was in the middle of debugging?
> Try fetching again.
> 
> I tried with both CONFIG_MEDIA_CONTROLLER and
> CONFIG_VIDEO_V4L2_SUBDEV_API enabled and both disabled, and
> I don't get the null deref in adv7180_set_pad_format.
> 
> 
>>
>> Your tree contains about 16 or so patches on top of linux-media for
>> imx6 capture. Are you close to the point where you will be posting a
>> patch series? If so, please CC me for testing with the adv7180 sensor.
> 
> I guess I can try posting a series again, but there will likely be push-back from
> Pengutronix. They have their own video capture driver for imx6. Last I heard (a while ago!)
> their version did not implement scaling, colorspace conversion, or image rotation via
> the IC. Instead their driver sends raw camera frames directly to memory, and image
> conversion is carried out by separate mem2mem device. Our capture driver does
> image conversion (scaling, CSC, and rotation) natively using the IC pre-processing channel.
> We also have a mem2mem device that does conversion using IC post-processing,
> which I have included in mx6-media-staging.
> 
> Also IIRC they did some pretty slick stuff with a video bus multiplexer subdev, which
> can multiplex video from different sensors either using the internal mux in the SoC,
> or can control an external mux via gpio. Our driver only supports the internal mux,
> and does it with a platform data function.
> 
> But like I said, I don't what the latest status is of the Pengutronix video capture support.
> 
> Btw, I just pushed an update of mx6-media-staging that implements vidioc_[gs]_selection.

Steve & Pengutronix,

I would be happy to add drivers to staging, either Steve's, Pengutronix or both.

The i.mx6 is quite popular and the lack of video capture support in the kernel is
a big stumbling block, especially given the pile of crap that freescale provides.

Having decent code in the kernel will help progress a lot I hope.

Regards,

	Hans