media: ov772x: avoid accessing registers under power saving mode

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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/i2c/ov772x.c b/drivers/media/i2c/ov772x.c
index 553c334c55b670c89e145e987f970948ecb69047..d380e75db76022f07e7c20e5aa5a5935ffa20666 100644 (file)
--- 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) {
+               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;
        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,