Re: [PATCH 2/5] media: adv748x: csi2: Link AFE with TXA and TXB

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Hi Jacopo,

Thank you for the patch,

On 11/12/2018 15:16, 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.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
>  drivers/media/i2c/adv748x/adv748x-csi2.c | 48 ++++++++++++++++++++------------
>  1 file changed, 30 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> index 6ce21542ed48..4d1aefc2c8d0 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
> + * @flags: Flags for the newly created link
>   *
>   * 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,
> +				      unsigned int flags)
>  {
> -	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;
> -

Yup - that part certainly needs to go ...

>  	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);
> +				     flags);
>  }
> 
>  /* -----------------------------------------------------------------------------
> @@ -68,24 +63,41 @@ 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 HDMI and AFE, 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 the AFE->TXB is.
>  	 */
> -	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_txa(tx) && is_afe_enabled(state))
> +	if (is_txa(tx)) {
> +		if (is_hdmi_enabled(state)) {
> +			ret = adv748x_csi2_register_link(tx, sd->v4l2_dev,
> +							 &state->hdmi.sd,
> +							 ADV748X_HDMI_SOURCE,
> +							 MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		if (is_afe_enabled(state)) {
> +			ret = adv748x_csi2_register_link(tx, sd->v4l2_dev,
> +							 &state->afe.sd,
> +							 ADV748X_AFE_SOURCE,
> +							 0);
> +			if (ret)
> +				return ret;
> +		}


> +	} else if (is_afe_enabled(state))

I believe when adding braces to one side of an if statement, we are
supposed to add to the else clauses too ?

>  		return adv748x_csi2_register_link(tx, sd->v4l2_dev,
>  						  &state->afe.sd,
> -						  ADV748X_AFE_SOURCE);
> +						  ADV748X_AFE_SOURCE,
> +						  MEDIA_LNK_FL_ENABLED);

Won't this enable the AFE link for both TXA and TXB ?
Which one will win? Just the last one ? the first one ?
Does it error?

(It might not be a problem ... I can't recall what the behaviour is)


> +

There are a lot of nested if's above, and I think we can simplify
greatly if we move the logic for the flags inside
adv748x_csi2_register_link(), and adjust the checks on is_xxx_enabled()

What do you think about the following pseudo code?:


int adv748x_csi2_register_link(struct adv748x_csi2 *tx,
  				      struct v4l2_device *v4l2_dev,
  				      struct v4l2_subdev *src,
				      unsigned int src_pad,
				      bool enable)
{

  int flags = 0;
  int ret;

  if (!src->v4l2_dev) {
	ret = v4l2_device_register_subdev(v4l2_dev, src)
	if (ret) return ret;
  }

  if (enable)
	flags = MEDIA_LNK_FL_ENABLED;

   return media_create_pad_link(&src->entity, src_pad,
 			        &tx->sd.entity, ADV748X_CSI2_SINK,
 			        flags);
}

int adv748x_csi2_registered(struct v4l2_subdev *sd)
{
  int ret;

  if (is_afe_enabled(state) {
      ret = adv748x_csi2_register_link(tx, sd->v4l2_dev, &state->afe.sd,
				   ADV748X_AFE_SOURCE, !is_txa(tx));
      if (ret)
	  return ret;
  }

  /* TX-B only supports AFE */
  if (!is_txa(tx) || !(is_hdmi_enabled(state))
	return 0;

  return adv748x_csi2_register_link(tx, sd->v4l2_dev, &state->hdmi.sd,
				    ADV748X_HDMI_SOURCE, true);
}


The above will for TXA:
	register_link(..., AFE_SOURCE, enable = false );
	register_link(..., HDMI_SOURCE, enable = true );

then TXB:
	register_link(..., AFE_SOURCE, enable = true );

Does that meet our needs?




>  	return 0;
>  }
> 
> --
> 2.7.4
> 

-- 
Regards
--
Kieran



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