Re: [PATCH 10/10] uvcvideo: Send control change events for slave ctrls when the master changes

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 03/28/2012 11:34 AM, Laurent Pinchart wrote:
> Hi Hans,
>
> Thanks for the patch.
>
> On Sunday 25 March 2012 13:56:50 Hans de Goede wrote:
>> This allows v4l2 control UI-s to update the inactive state (ie grey-ing
>> out of controls) for slave controls when the master control changes.
>>
>> Signed-off-by: Hans de Goede<hdegoede@redhat.com>
>> ---
>>   drivers/media/video/uvc/uvc_ctrl.c |   55 +++++++++++++++++++++++++++++++--
>>   1 file changed, 52 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/video/uvc/uvc_ctrl.c
>> b/drivers/media/video/uvc/uvc_ctrl.c index 91d9007..2d06fd8 100644
>> --- a/drivers/media/video/uvc/uvc_ctrl.c
>> +++ b/drivers/media/video/uvc/uvc_ctrl.c
>
> [snip]
>
>> +static void uvc_ctrl_send_events(struct uvc_fh *handle,
>> +	struct v4l2_ext_control *xctrls, int xctrls_count)
>> +{
>> +	struct uvc_control_mapping *mapping;
>> +	struct uvc_control *ctrl;
>> +	u32 changes = V4L2_EVENT_CTRL_CH_VALUE;
>> +	int i, j;
>> +
>>   	for (i = 0; i<  xctrls_count; ++i) {
>>   		ctrl = uvc_find_control(handle->chain, xctrls[i].id,&mapping);
>> +
>> +		for (j = 0; j<  ARRAY_SIZE(mapping->slave_ids); ++j) {
>> +			if (!mapping->slave_ids[j])
>> +				break;
>> +			uvc_ctrl_send_slave_event(handle,
>> +						  mapping->slave_ids[j],
>> +						  xctrls, xctrls_count);
>> +		}
>> +
>> +		/*
>> +		 * If the master is being modified in the same transaction
>> +		 * flags may change too.
>> +		 */
>> +		if (mapping->master_id)
>> +			for (j = 0; j<  xctrls_count; j++)
>> +				if (xctrls[j].id == mapping->master_id) {
>> +					changes |= V4L2_EVENT_CTRL_CH_FLAGS;
>
> Should you verify that the modification to the master control actually caused
> a slave control flags change, or would that be overkill ?

I think that that would be overkill. This sending of events for flag changes
already is not 100% trivial and I think keeping it KISS and occasionally sending
an unneeded change event is better then making the code more complicated.


>
>> +					break;
>> +				}
>
> Could you please put brackets around the for and the if ?

Will do.

Regards,

Hans