Re: [PATCH] vivid: fix gain when autogain is on

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Fri, 29 Jun 2018 11:40:41 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> In the vivid driver you want gain to continuous change while autogain
> is on. However, dev->jiffies_vid_cap doesn't actually change. It probably
> did in the past, but changes in the code caused this to be a fixed value
> that is only set when you start streaming.
> 
> Replace it by jiffies, which is always changing.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> ---
> diff --git a/drivers/media/platform/vivid/vivid-ctrls.c b/drivers/media/platform/vivid/vivid-ctrls.c
> index 6b0bfa091592..6eb8ad7fb12c 100644
> --- a/drivers/media/platform/vivid/vivid-ctrls.c
> +++ b/drivers/media/platform/vivid/vivid-ctrls.c
> @@ -295,7 +295,7 @@ static int vivid_user_vid_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
> 
>  	switch (ctrl->id) {
>  	case V4L2_CID_AUTOGAIN:
> -		dev->gain->val = dev->jiffies_vid_cap & 0xff;
> +		dev->gain->val = (jiffies / HZ) & 0xff;

Manipulating jiffies directly like the above is not a good idea.

Better to use, instead:

	dev->gain->val = (jiffies_to_msecs(jiffies) / 1000) & 0xff;

I'll change the code when applying the patch.


Thanks,
Mauro