Re: [PATCH 5/5] rcar-vin: Add support for suspend and resume

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Hi Niklas,

On Fri, Oct 16, 2020 at 01:14:08AM +0200, Niklas Söderlund wrote:
> Add support for suspend and resume by stopping and starting the video
> pipeline while still retaining all buffers given to the driver by
> user-space and internally allocated ones, this gives the application a
> seamless experience.
>
> Buffers are never returned to user-space unprocessed so user-space don't
> notice when suspending. When resuming the driver restarts the capture
> session using the internal scratch buffer, this happens before
> user-space is unfrozen, this leads to speedy response times once the
> application resumes its execution.
>
> As the entire pipeline is stopped on suspend all subdevices in use are
> also stopped, and if they enter a shutdown state when not streaming
> (such as the R-Car CSI-2 driver) they too will be suspended and resumed
> in sync with the VIN driver.
>
> To be able to do keep track of which VINs should be resumed a new

s/to do/to/

> internal state SUSPENDED is added to recode this.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
>  drivers/media/platform/rcar-vin/rcar-core.c | 51 +++++++++++++++++++++
>  drivers/media/platform/rcar-vin/rcar-vin.h  | 10 ++--
>  2 files changed, 57 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/rcar-vin/rcar-core.c b/drivers/media/platform/rcar-vin/rcar-core.c
> index 34d003e0e9b9c25a..4adf4ce518f79c93 100644
> --- a/drivers/media/platform/rcar-vin/rcar-core.c
> +++ b/drivers/media/platform/rcar-vin/rcar-core.c
> @@ -918,6 +918,54 @@ static int rvin_mc_init(struct rvin_dev *vin)
>  	return ret;
>  }
>
> +/* -----------------------------------------------------------------------------
> + * Suspend / Resume
> + */
> +
> +static int __maybe_unused rvin_suspend(struct device *dev)
> +{
> +	struct rvin_dev *vin = dev_get_drvdata(dev);
> +
> +	if (vin->state != RUNNING)
> +		return 0;
> +
> +	rvin_stop_streaming(vin);

This delay suspend untill all the userspace queued buffers are not
completed, right ?

> +
> +	vin->state = SUSPENDED;
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused rvin_resume(struct device *dev)
> +{
> +	struct rvin_dev *vin = dev_get_drvdata(dev);
> +
> +	if (vin->state != SUSPENDED)
> +		return 0;
> +
> +	/*
> +	 * Restore group master CHSEL setting.
> +	 *
> +	 * This needs to be by every VIN resuming not only the master
> +	 * as we don't know if and in which order the master VINs will
> +	 * be resumed.
> +	 */
> +	if (vin->info->use_mc) {
> +		unsigned int master_id = rvin_group_id_to_master(vin->id);
> +		struct rvin_dev *master = vin->group->vin[master_id];
> +		int ret;
> +
> +		if (WARN_ON(!master))
> +			return -ENODEV;
> +
> +		ret = rvin_set_channel_routing(master, master->chsel);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return rvin_start_streaming(vin);
> +}
> +
>  /* -----------------------------------------------------------------------------
>   * Platform Device Driver
>   */
> @@ -1421,9 +1469,12 @@ static int rcar_vin_remove(struct platform_device *pdev)
>  	return 0;
>  }
>
> +static SIMPLE_DEV_PM_OPS(rvin_pm_ops, rvin_suspend, rvin_resume);
> +
>  static struct platform_driver rcar_vin_driver = {
>  	.driver = {
>  		.name = "rcar-vin",
> +		.pm = &rvin_pm_ops,
>  		.of_match_table = rvin_of_id_table,
>  	},
>  	.probe = rcar_vin_probe,
> diff --git a/drivers/media/platform/rcar-vin/rcar-vin.h b/drivers/media/platform/rcar-vin/rcar-vin.h
> index 4ec8584709c847a9..4539bd53d9d41e9c 100644
> --- a/drivers/media/platform/rcar-vin/rcar-vin.h
> +++ b/drivers/media/platform/rcar-vin/rcar-vin.h
> @@ -49,16 +49,18 @@ enum rvin_csi_id {
>  };
>
>  /**
> - * STOPPED  - No operation in progress
> - * STARTING - Capture starting up
> - * RUNNING  - Operation in progress have buffers
> - * STOPPING - Stopping operation
> + * STOPPED   - No operation in progress
> + * STARTING  - Capture starting up
> + * RUNNING   - Operation in progress have buffers
> + * STOPPING  - Stopping operation
> + * SUSPENDED - Capture is suspended
>   */
>  enum rvin_dma_state {
>  	STOPPED = 0,
>  	STARTING,
>  	RUNNING,
>  	STOPPING,
> +	SUSPENDED,
>  };
>
>  /**
> --
> 2.28.0
>



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