netdev - Re: [PATCH v2 1/2] bus: mhi: Remove auto-start option

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Message-ID: <20b95a1bd31bedc20ce03c5efc1bdd02@codeaurora.org>
Date:   Mon, 21 Sep 2020 11:42:16 -0700
From:   bbhatt@...eaurora.org
To:     Loic Poulain <loic.poulain@...aro.org>, clew@...eaurora.org
Cc:     manivannan.sadhasivam@...aro.org, hemantk@...eaurora.org,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, bjorn.andersson@...aro.org
Subject: Re: [PATCH v2 1/2] bus: mhi: Remove auto-start option

On 2020-09-21 00:43, 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@...aro.org>
> ---
>  v2: split MHI and qrtr changes in dedicated commits
> 
>  drivers/bus/mhi/core/init.c     | 9 ---------
>  drivers/bus/mhi/core/internal.h | 1 -
>  include/linux/mhi.h             | 2 --
>  3 files changed, 12 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index dccc824..8798deb 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -721,7 +721,6 @@ 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
> @@ -1119,11 +1118,6 @@ 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;
> @@ -1157,9 +1151,6 @@ 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 811e686..0d277c7 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;
>  };

Chris, are you OK with this? It will change the current behavior where 
MHI will
not start the up link channel before providing QRTR with a probe.