On 02/25/15 15:22, Sakari Ailus wrote:
> Hi Hans,
>
> On Wed, Feb 25, 2015 at 03:14:16PM +0100, Hans Verkuil wrote:
>> On 02/25/15 14:57, Sakari Ailus wrote:
>>> Hi Hans,
>>>
>>> On Wed, Feb 25, 2015 at 02:45:58PM +0100, Hans Verkuil wrote:
>>> ...
>>>>> @@ -1535,15 +1529,15 @@ static int smiapp_set_stream(struct v4l2_subdev *subdev, int enable)
>>>>> if (sensor->streaming == enable)
>>>>> goto out;
>>>>>
>>>>> - if (enable) {
>>>>> - sensor->streaming = true;
>>>>> + if (enable)
>>>>> rval = smiapp_start_streaming(sensor);
>>>>> - if (rval < 0)
>>>>> - sensor->streaming = false;
>>>>> - } else {
>>>>> + else
>>>>> rval = smiapp_stop_streaming(sensor);
>>>>> - sensor->streaming = false;
>>>>> - }
>>>>> +
>>>>> + sensor->streaming = enable;
>>>>> + __v4l2_ctrl_grab(sensor->hflip, enable);
>>>>> + __v4l2_ctrl_grab(sensor->vflip, enable);
>>>>> + __v4l2_ctrl_grab(sensor->link_freq, enable);
>>>>
>>>> Just checking: is it really not possible to change these controls
>>>> while streaming? Most devices I know of allow changing this on the fly.
>>>>
>>>> If it is really not possible, then you can add my Ack for this series:
>>>
>>> I'm not sure what the sensors would do in practice, but the problem is that
>>> changing the values of these control affect the pixel order. That's why
>>> changing them has been prevented while streaming.
>>
>> Ah, OK.
>>
>> Can you add a comment explaining why this is done?
>>
>> BTW, I understand that HFLIP will cause changes in the pixel order,
>> but VFLIP and link_freq should be OK, I would expect.
>
> Sure I can add a comment. Same for vflip, it will change the pixel order.
> The flip controls will change the readout direction. For example, a 4x4
> bayer sensor:
>
> GRGR
> BGBG
> GRGR
> BGBG
>
> Without flipping, the readout of the first line will be GRGR while the
> second is BGBG. With vertical flipping, the first line read out from the
> sensor will be BGBG and the second GRGR.
Ah, of course. A comment would be useful indeed as this is not immediately
obvious (well, not to me at least!).
>
> The link frequency cannot be changed since this would change the sensor PLL
> configuration and the CSI-2 bus frequency, neither of which are changeable
> while streaming.
>
Sorry, my mistake. I confused the link frequency with the powerline frequency
control (50/60 Hz). Of course the link frequency can't be changed while
streaming.
Regards,
Hans
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