On 02/09/2018 07:01 AM, Tim Harvey wrote:
>>> +static int
>>> +tda1997x_g_input_status(struct v4l2_subdev *sd, u32 *status)
>>> +{
>>> + struct tda1997x_state *state = to_state(sd);
>>> +
>>> + mutex_lock(&state->lock);
>>> + if (state->detected_timings)
>>
>> What this actually tests if the driver was able to detect a valid signal
>> and lock to it.
>>
>> In practice you have three possible outcomes:
>>
>> - There is no HDMI signal at all: return V4L2_IN_ST_NO_SIGNAL
>> - There is a signal, but the receiver could not lock to it: return V4L2_IN_ST_NO_SYNC
>> - There is a signal, and the receiver could lock: return 0.
>>
>> Just because this returns 0, doesn't mean that QUERY_DV_TIMINGS will succeed.
>> There may be other constraints (e.g. the driver doesn't support certain formats
>> such as interlaced) that can cause QUERY_DV_TIMINGS to return an error, even
>> though the receiver could sync.
>>
>> Usually the hardware has some bits that tell whether there is a signal
>> (usually the TMDS clock) and whether it could sync or not (H and V syncs).
>>
>> That's really all you need to test here.
>
> makes sense. I don't have any decent documentation on the TMDS regs
> used in tda1997x_read_activity_status but I can use the some other
> things to determine this.
>
> I don't see v4l2-subdev.c (or anything) ever calling g_input_status.
> How do I test this?
Huh, that's a very good question! It is meant to be called by bridge
drivers implementing VIDIOC_ENUMINPUT. But that doesn't apply to the imx
driver since it is expecting userspace to talk directly to the subdev.
Now for the DV_TIMINGS API this doesn't matter all that much since
QUERY_DV_TIMINGS can do the same job through the returned error code, but
for analog TV there is no such option (QUERYSTD doesn't support such
detailed feedback).
I see that you have an adv7180 in your system. Can you run
'v4l2-compliance -uX' for the adv7180 subdev and post the output here?
Analog TV receivers are rare in MC bridge drivers, and I see that the subdev
API doesn't even support the G/S/QUERY/ENUM_STD ioctls! I think the adv7180 is
basically unusable in your system. And we need a subdev replacement for
VIDIOC_ENUMINPUT.
Was the adv7180 ever tested? Are you able to test it?
Regards,
Hans
