Hi Niklas,
   sorry for replying late

On Wed, Jan 16, 2019 at 02:44:25PM +0100, Niklas Söderlund wrote:
> Hi (again) Jacopo,
>
> I found something else in this patch unfortunately :-(
>
> On 2019-01-14 15:55:33 +0100, Niklas Söderlund wrote:
> > Hi Jacopo,
> >
> > Thanks for your patch.
> >
> > On 2019-01-10 15:02:10 +0100, Jacopo Mondi wrote:
> > > The ADV748x chip supports routing AFE output to either TXA or TXB.
> > > In order to support run-time configuration of video stream path, create an
> > > additional (not enabled) "AFE:8->TXA:0" link, and remove the IMMUTABLE flag
> > > from existing ones.
> > >
> > > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> > > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > > ---
> > >  drivers/media/i2c/adv748x/adv748x-csi2.c | 44 +++++++++++++-----------
> > >  1 file changed, 23 insertions(+), 21 deletions(-)
> > >
> > > diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > > index b6b5d8c7ea7c..8c3714495e11 100644
> > > --- a/drivers/media/i2c/adv748x/adv748x-csi2.c
> > > +++ b/drivers/media/i2c/adv748x/adv748x-csi2.c
> > > @@ -27,6 +27,7 @@ static int adv748x_csi2_set_virtual_channel(struct adv748x_csi2 *tx,
> > >   * @v4l2_dev: Video registration device
> > >   * @src: Source subdevice to establish link
> > >   * @src_pad: Pad number of source to link to this @tx
> > > + * @enable: Link enabled flag
> > >   *
> > >   * Ensure that the subdevice is registered against the v4l2_device, and link the
> > >   * source pad to the sink pad of the CSI2 bus entity.
> > > @@ -34,17 +35,11 @@ static int adv748x_csi2_set_virtual_channel(struct adv748x_csi2 *tx,
> > >  static int adv748x_csi2_register_link(struct adv748x_csi2 *tx,
> > >  				      struct v4l2_device *v4l2_dev,
> > >  				      struct v4l2_subdev *src,
> > > -				      unsigned int src_pad)
> > > +				      unsigned int src_pad,
> > > +				      bool enable)
> > >  {
> > > -	int enabled = MEDIA_LNK_FL_ENABLED;
> > >  	int ret;
> > >
> > > -	/*
> > > -	 * Dynamic linking of the AFE is not supported.
> > > -	 * Register the links as immutable.
> > > -	 */
> > > -	enabled |= MEDIA_LNK_FL_IMMUTABLE;
> > > -
> > >  	if (!src->v4l2_dev) {
> > >  		ret = v4l2_device_register_subdev(v4l2_dev, src);
> > >  		if (ret)
> > > @@ -53,7 +48,7 @@ static int adv748x_csi2_register_link(struct adv748x_csi2 *tx,
> > >
> > >  	return media_create_pad_link(&src->entity, src_pad,
> > >  				     &tx->sd.entity, ADV748X_CSI2_SINK,
> > > -				     enabled);
> > > +				     enable ? MEDIA_LNK_FL_ENABLED : 0);
> > >  }
> > >
> > >  /* -----------------------------------------------------------------------------
> > > @@ -68,25 +63,32 @@ static int adv748x_csi2_registered(struct v4l2_subdev *sd)
> > >  {
> > >  	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> > >  	struct adv748x_state *state = tx->state;
> > > +	int ret;
> > >
> > >  	adv_dbg(state, "Registered %s (%s)", is_txa(tx) ? "TXA":"TXB",
> > >  			sd->name);
> > >
> > >  	/*
> > > -	 * The adv748x hardware allows the AFE to route through the TXA, however
> > > -	 * this is not currently supported in this driver.
> > > +	 * Link TXA to AFE and HDMI, and TXB to AFE only as TXB cannot output
> > > +	 * HDMI.
> > >  	 *
> > > -	 * Link HDMI->TXA, and AFE->TXB directly.
> > > +	 * The HDMI->TXA link is enabled by default, as is the AFE->TXB one.
> > >  	 */
> > > -	if (is_txa(tx) && is_hdmi_enabled(state))
> > > -		return adv748x_csi2_register_link(tx, sd->v4l2_dev,
> > > -						  &state->hdmi.sd,
> > > -						  ADV748X_HDMI_SOURCE);
> > > -	if (is_txb(tx) && is_afe_enabled(state))
> > > -		return adv748x_csi2_register_link(tx, sd->v4l2_dev,
> > > -						  &state->afe.sd,
> > > -						  ADV748X_AFE_SOURCE);
> > > -	return 0;
> > > +	if (is_afe_enabled(state)) {
> > > +		ret = adv748x_csi2_register_link(tx, sd->v4l2_dev,
> > > +						 &state->afe.sd,
> > > +						 ADV748X_AFE_SOURCE,
> > > +						 is_txb(tx));
> > > +		if (ret)
> > > +			return ret;
> > > +	}
> > > +
> > > +	/* Register link to HDMI for TXA only. */
> > > +	if (is_txb(tx) || !is_hdmi_enabled(state))
> >
> > Small nit, I would s/is_txb(tx)/!is_txa(tx)/ here as to me it becomes
> > easier to read. With or without this change,
> >
> > Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> >
> > > +		return 0;
> > > +
> > > +	return adv748x_csi2_register_link(tx, sd->v4l2_dev, &state->hdmi.sd,
> > > +					  ADV748X_HDMI_SOURCE, true);
>
> If the call to adv748x_csi2_register_link() fails should not the
> (possible) link to the AFE be removed?
>

The .register() callback is called from v4l2-device.c in
v4l2_device_register_subdev(). If the callback returns an error, the
subdev gets not registered at all and the media entity cleaned up, so it
won't appear in the media graph.

I think we're safe and the patch series is good to go. What's your
opinion?

Thanks
  j


> > >  }
> > >
> > >  static const struct v4l2_subdev_internal_ops adv748x_csi2_internal_ops = {
> > > --
> > > 2.20.1
> > >
> >
> > --
> > Regards,
> > Niklas Söderlund
>
> --
> Regards,
> Niklas Söderlund