Re: [PATCH] bus: mhi: Remove auto-start option

[bbhatt@xxxxxxxxxxxxxx]

On 2020-09-18 03:16, Loic Poulain wrote:
> There is really no point having an auto-start for channels.
> This is confusing for the device drivers, some have to enable the
> channels, others don't have... and waste resources (e.g. pre allocated
> buffers) that may never be used.
>
> This is really up to the MHI device(channel) driver to manage the state
> of its channels.
>
> Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
> ---
>  drivers/bus/mhi/core/init.c     | 9 ---------
>  drivers/bus/mhi/core/internal.h | 1 -
>  include/linux/mhi.h             | 2 --
>  net/qrtr/mhi.c                  | 5 +++++
>  4 files changed, 5 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index ac19067..7aef6b7 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -727,7 +727,6 @@ static int parse_ch_cfg(struct mhi_controller 
> *mhi_cntrl,
>  		mhi_chan->offload_ch = ch_cfg->offload_channel;
>  		mhi_chan->db_cfg.reset_req = ch_cfg->doorbell_mode_switch;
>  		mhi_chan->pre_alloc = ch_cfg->auto_queue;
> -		mhi_chan->auto_start = ch_cfg->auto_start;
>
>  		/*
>  		 * If MHI host allocates buffers, then the channel direction
> @@ -1125,11 +1124,6 @@ static int mhi_driver_probe(struct device *dev)
>  			goto exit_probe;
>
>  		ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
> -		if (ul_chan->auto_start) {
> -			ret = mhi_prepare_channel(mhi_cntrl, ul_chan);
> -			if (ret)
> -				goto exit_probe;
> -		}
>  	}
>
>  	ret = -EINVAL;
> @@ -1163,9 +1157,6 @@ static int mhi_driver_probe(struct device *dev)
>  	if (ret)
>  		goto exit_probe;
>
> -	if (dl_chan && dl_chan->auto_start)
> -		mhi_prepare_channel(mhi_cntrl, dl_chan);
> -
>  	mhi_device_put(mhi_dev);
>
>  	return ret;
> diff --git a/drivers/bus/mhi/core/internal.h 
> b/drivers/bus/mhi/core/internal.h
> index 5a81a42..73b52a0 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -563,7 +563,6 @@ struct mhi_chan {
>  	bool configured;
>  	bool offload_ch;
>  	bool pre_alloc;
> -	bool auto_start;
>  	bool wake_capable;
>  };
>
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 008b8f6..742dabe 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -214,7 +214,6 @@ enum mhi_db_brst_mode {
>   * @offload_channel: The client manages the channel completely
>   * @doorbell_mode_switch: Channel switches to doorbell mode on M0 
> transition
>   * @auto_queue: Framework will automatically queue buffers for DL 
> traffic
> - * @auto_start: Automatically start (open) this channel
>   * @wake-capable: Channel capable of waking up the system
>   */
>  struct mhi_channel_config {
> @@ -232,7 +231,6 @@ struct mhi_channel_config {
>  	bool offload_channel;
>  	bool doorbell_mode_switch;
>  	bool auto_queue;
> -	bool auto_start;
>  	bool wake_capable;
>  };
>
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> index ff0c414..7100f0b 100644
> --- a/net/qrtr/mhi.c
> +++ b/net/qrtr/mhi.c
> @@ -76,6 +76,11 @@ static int qcom_mhi_qrtr_probe(struct mhi_device 
> *mhi_dev,
>  	struct qrtr_mhi_dev *qdev;
>  	int rc;
>
> +	/* start channels */
> +	rc = mhi_prepare_for_transfer(mhi_dev);
> +	if (rc)
> +		return rc;
> +
>  	qdev = devm_kzalloc(&mhi_dev->dev, sizeof(*qdev), GFP_KERNEL);
>  	if (!qdev)
>  		return -ENOMEM;
Hi Loic,

Thank you for your patch. Hemant and I discussed and we are OK with this 
patch.

Adding Chris to ensure that QRTR changes are acceptable.

Thanks,
Bhaumik

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