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

Hans de Goede
2012-03-28T14:09:57Z

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