On 01/06/2020 10:31, Hans Verkuil wrote:
> Hi Luca,
>
> On 31/05/2020 23:56, Luca Ceresoli wrote:
>> Hi Sowjanya,
>>
>> On 29/05/20 04:07, Sowjanya Komatineni wrote:
>>> Hi Luca,
>>>
>>> Quick question regarding IMX274 driver that was up streamed by you.
>>
>> Well, to be fair I only added cropping and made some improvements.
>>
>>> Upstream IMX274 driver programs Y_OUT_SIZE correctly based on IMX274
>>> datasheet and register mode table for Y_OUT_SIZE where it includes 6
>>> ignored area of effective pixels + 8 effective margin for color
>>> processing pixels.
>>>
>>> So, Y_OUT_SIZE register value = height + 14
>>>
>>> But somehow with this we are not seeing full frame on CSI.
>>>
>>> In our internal NVIDIA IMX274 driver, we are programming Y_OUT_SIZE to
>>> exact height Y_OUT_SIZE = height
>>>
>>> So for debug, followed the same and updated upstream IMX274 driver to
>>> program Y_OUT_SIZE = crop.height locally and I see all resolutions
>>> working fine with this.
>>>
>>> Checking with Sony on whats causing sensor not to send full frame when
>>> Y_OUT_SIZE is set to height + 14.
>>>
>>> But thought to check with you in parallel if there are any known issues
>>
>> That's strange. Unfortunately I'm not using imx274 anymore since a long
>> time and don't remember the details, but definitely I did test it and if
>> there had been 14 missing lines I'm pretty sure I would have noticed.
>>
>> I'll see if I can remember anything useful, and in case I'll update you.
>> I would be glad if you can update me on any findings too, maybe they
>> will help in understanding the problem better.
>
> The '+ 14' makes no sense. I wonder if this was perhaps to compensate for
> some problem in the bridge driver that this sensor was connected to.
> Which bridge driver did you use for testing? Do you remember where you got
> the '+ 14' from?
Hmm, this comes from the first version of this driver where Y_OUT_SIZE
was set to 0x87e (2160 + 14). This in turn comes from the datasheet ('Register
Setting for Each Readout Drive Mode').
Looking at the "Detailed Specification of Each Mode" (page 63 in my copy of
the datasheet) I see three additional parameters: "Front ignore area of
effective pixel", "Front effective margin for color processing" and "Rear
effective margin for color processing", these are 6, 4 and 4, which is a
total of 14.
So I guess that's where the 14 comes from.
Knowing with which bridge driver this was tested will definitely be helpful.
Regards,
Hans
