Hi Akinobu,
let me see if I got this right...
On Mon, Apr 30, 2018 at 02:13:11AM +0900, Akinobu Mita wrote:
> The set_fmt() in subdev pad ops, the s_ctrl() for subdev control handler,
> and the s_frame_interval() in subdev video ops could be called when the
> device is under power saving mode. These callbacks for ov772x driver
> cause updating H/W registers that will fail under power saving mode.
>
> This avoids it by not apply any changes to H/W if the device is not powered
> up. Instead the changes will be restored right after power-up.
>
> Cc: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
> ---
> * v4
> - No changes
>
> drivers/media/i2c/ov772x.c | 79 +++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 64 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
> index 3e6ca98..bd37169 100644
> --- a/drivers/media/i2c/ov772x.c
> +++ b/drivers/media/i2c/ov772x.c
> @@ -741,19 +741,30 @@ static int ov772x_s_frame_interval(struct v4l2_subdev *sd,
> struct ov772x_priv *priv = to_ov772x(sd);
> struct v4l2_fract *tpf = &ival->interval;
> unsigned int fps;
> - int ret;
> + int ret = 0;
>
> fps = ov772x_select_fps(priv, tpf);
>
> - ret = ov772x_set_frame_rate(priv, fps, priv->cfmt, priv->win);
> - if (ret)
> - return ret;
> + mutex_lock(&priv->lock);
> + /*
> + * If the device is not powered up by the host driver do
> + * not apply any changes to H/W at this time. Instead
> + * the frame rate will be restored right after power-up.
> + */
> + if (priv->power_count > 0) {
If I'm not wrong this is not protected when the device is
streaming.
Since Hans' series frame control is called by g/s_parm (until a new
ioctl is not introduced) and I've looked at the call stack and it
seems to me it does not check for active streaming[1]. I -think-
this is even worse when this is called on the subdev, as there is
no shared notion of active streaming. Am I wrong?
If you have to check for active streaming here (I see some other
drivers doing that, eg ov5640), then I see two ways, or you just
return -EBUSY, or you save the desired FPS for later, but then it gets
messy as you won't be able to just restore paramters at power_on()
time, but you would need to do that also at start streaming time.
My opinion is that you should check for streaming active (as you're
doing for the set_fmt() function in [13/14], do you agree?
[1] This calls for a device wise 'streaming' state handler. Maybe it's
there but I failed to find checks for that.
> + ret = ov772x_set_frame_rate(priv, fps, priv->cfmt, priv->win);
> + if (ret)
> + goto error;
> + }
>
> tpf->numerator = 1;
> tpf->denominator = fps;
> priv->fps = fps;
>
> - return 0;
> +error:
> + mutex_unlock(&priv->lock);
> +
> + return ret;
> }
>
> static int ov772x_s_ctrl(struct v4l2_ctrl *ctrl)
> @@ -765,6 +776,16 @@ static int ov772x_s_ctrl(struct v4l2_ctrl *ctrl)
> int ret = 0;
> u8 val;
>
> + /* v4l2_ctrl_lock() locks our own mutex */
> +
> + /*
> + * If the device is not powered up by the host driver do
> + * not apply any controls to H/W at this time. Instead
> + * the controls will be restored right after power-up.
> + */
> + if (priv->power_count == 0)
> + return 0;
> +
> switch (ctrl->id) {
> case V4L2_CID_VFLIP:
> val = ctrl->val ? VFLIP_IMG : 0x00;
> @@ -885,6 +906,10 @@ static int ov772x_power_off(struct ov772x_priv *priv)
> return 0;
> }
>
> +static int ov772x_set_params(struct ov772x_priv *priv,
> + const struct ov772x_color_format *cfmt,
> + const struct ov772x_win_size *win);
> +
> static int ov772x_s_power(struct v4l2_subdev *sd, int on)
> {
> struct ov772x_priv *priv = to_ov772x(sd);
> @@ -895,8 +920,20 @@ static int ov772x_s_power(struct v4l2_subdev *sd, int on)
> /* If the power count is modified from 0 to != 0 or from != 0 to 0,
> * update the power state.
> */
> - if (priv->power_count == !on)
> - ret = on ? ov772x_power_on(priv) : ov772x_power_off(priv);
> + if (priv->power_count == !on) {
> + if (on) {
> + ret = ov772x_power_on(priv);
> + /*
> + * Restore the format, the frame rate, and
> + * the controls
> + */
> + if (!ret)
> + ret = ov772x_set_params(priv, priv->cfmt,
> + priv->win);
> + } else {
> + ret = ov772x_power_off(priv);
> + }
> + }
>
> if (!ret) {
> /* Update the power count. */
> @@ -1163,7 +1200,7 @@ static int ov772x_set_fmt(struct v4l2_subdev *sd,
> struct v4l2_mbus_framefmt *mf = &format->format;
> const struct ov772x_color_format *cfmt;
> const struct ov772x_win_size *win;
> - int ret;
> + int ret = 0;
>
> if (format->pad)
> return -EINVAL;
> @@ -1184,14 +1221,24 @@ static int ov772x_set_fmt(struct v4l2_subdev *sd,
> return 0;
> }
>
> - ret = ov772x_set_params(priv, cfmt, win);
> - if (ret < 0)
> - return ret;
> -
> + mutex_lock(&priv->lock);
> + /*
> + * If the device is not powered up by the host driver do
> + * not apply any changes to H/W at this time. Instead
> + * the format will be restored right after power-up.
> + */
> + if (priv->power_count > 0) {
> + ret = ov772x_set_params(priv, cfmt, win);
> + if (ret < 0)
> + goto error;
> + }
> priv->win = win;
> priv->cfmt = cfmt;
>
> - return 0;
> +error:
> + mutex_unlock(&priv->lock);
> +
> + return ret;
> }
>
> static int ov772x_video_probe(struct ov772x_priv *priv)
> @@ -1201,7 +1248,7 @@ static int ov772x_video_probe(struct ov772x_priv *priv)
> const char *devname;
> int ret;
>
> - ret = ov772x_s_power(&priv->subdev, 1);
> + ret = ov772x_power_on(priv);
> if (ret < 0)
> return ret;
>
> @@ -1241,7 +1288,7 @@ static int ov772x_video_probe(struct ov772x_priv *priv)
> ret = v4l2_ctrl_handler_setup(&priv->hdl);
>
> done:
> - ov772x_s_power(&priv->subdev, 0);
> + ov772x_power_off(priv);
>
> return ret;
> }
> @@ -1340,6 +1387,8 @@ static int ov772x_probe(struct i2c_client *client,
>
> v4l2_i2c_subdev_init(&priv->subdev, client, &ov772x_subdev_ops);
> v4l2_ctrl_handler_init(&priv->hdl, 3);
> + /* Use our mutex for the controls */
> + priv->hdl.lock = &priv->lock;
This is unrelated and should probably go in the previous patch (which
I would move before the one where you split s_frame_interval up, for
clearness)
Thanks
j
> priv->vflip_ctrl = v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops,
> V4L2_CID_VFLIP, 0, 1, 1, 0);
> priv->hflip_ctrl = v4l2_ctrl_new_std(&priv->hdl, &ov772x_ctrl_ops,
> --
> 2.7.4
>
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