Re: [PATCH v2 4/4] rcar-csi2: Do not try to recover after transfer error

[Hans Verkuil <hverkuil@xs4all.nl>]

On 15/01/2021 01:21, Niklas Söderlund wrote:
> Instead of restarting the R-Car CSI-2 receiver if a transmission error
> is detected inform the R-Car VIN driver of the error so it can stop the
> whole pipeline and inform user-space. This is done to reflect a updated
> usage recommendation in later versions of the datasheet.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
>  drivers/media/platform/rcar-vin/rcar-csi2.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-csi2.c b/drivers/media/platform/rcar-vin/rcar-csi2.c
> index 945d2eb8723367f0..a7212ecc46572a3b 100644
> --- a/drivers/media/platform/rcar-vin/rcar-csi2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-csi2.c
> @@ -773,21 +773,19 @@ static irqreturn_t rcsi2_irq(int irq, void *data)
>  
>  	rcsi2_write(priv, INTERRSTATE_REG, err_status);
>  
> -	dev_info(priv->dev, "Transfer error, restarting CSI-2 receiver\n");
> -
>  	return IRQ_WAKE_THREAD;
>  }
>  
>  static irqreturn_t rcsi2_irq_thread(int irq, void *data)
>  {
>  	struct rcar_csi2 *priv = data;
> +	struct v4l2_event event = {
> +		.type = V4L2_EVENT_EOS,
> +	};
>  
> -	mutex_lock(&priv->lock);
> -	rcsi2_stop(priv);
> -	usleep_range(1000, 2000);
> -	if (rcsi2_start(priv))
> -		dev_warn(priv->dev, "Failed to restart CSI-2 receiver\n");
> -	mutex_unlock(&priv->lock);
> +	dev_err(priv->dev, "Transfer error detected.\n");

You probably want to call vb2_queue_error() here. Typically once
something like this happens you have to restart everything and marking
the queue as 'error' will ensure that VIDIOC_QBUF will return an error
until the queue is reset (STREAMOFF).

It doesn't hurt to also raise the EOS event, I'm fine with that.

Regards,

	Hans

> +
> +	v4l2_subdev_notify_event(&priv->subdev, &event);
>  
>  	return IRQ_HANDLED;
>  }
>