Re: [PATCH RFC v2 2/8] bus: mhi: host: add new interfaces to handle MHI channels directly

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Nov 27, 2023 at 06:20:16PM +0200, Kalle Valo wrote:
> From: Baochen Qiang <quic_bqiang@quicinc.com>
> 
> When using mhi_power_down_no_destroy() MHI hosts need to unprepare MHI channels
> by themselves.  Similarly, MHI stack will also not create new MHI device since
> old devices were not destroyed, so MHI hosts need to prepare channels as well.
> Hence add these two interfaces to make that possible.
> 
> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
> 
> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
> ---
>  drivers/bus/mhi/host/main.c | 107 ++++++++++++++++++++++++++++++++++++
>  include/linux/mhi.h         |  20 ++++++-
>  2 files changed, 126 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index d80975f4bba8..3f677fc628ad 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1669,6 +1669,58 @@ int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev)
>  }
>  EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer_autoqueue);
>  
> +static int ____mhi_prepare_for_transfer(struct device *dev, void *data)

"__mhi_prepare_all_for_transfer"

> +{
> +	struct mhi_device *mhi_dev;
> +	struct mhi_chan *ul_chan, *dl_chan;
> +	enum mhi_ee_type ee = MHI_EE_MAX;

Reverse Xmas order, please.

> +
> +	if (dev->bus != &mhi_bus_type)
> +		return 0;
> +
> +	mhi_dev = to_mhi_device(dev);
> +
> +	/* Only prepare virtual devices that are attached to bus */

"Only prepare virtual devices for the channels". Here and below.

> +	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
> +		return 0;
> +
> +	/* There are cases where there is no MHI client driver matches
> +	 * this device, we are not allowed to do prepare for it.
> +	 */

Use the preferred style for comment:

	/*
	 * ...
	 */

> +	if (!mhi_dev->id)
> +		return 0;
> +
> +	ul_chan = mhi_dev->ul_chan;
> +	dl_chan = mhi_dev->dl_chan;
> +
> +	/*
> +	 * If execution environment is specified, remove only those devices that
> +	 * started in them based on ee_mask for the channels as we move on to a
> +	 * different execution environment
> +	 */
> +	if (data)
> +		ee = *(enum mhi_ee_type *)data;
> +
> +	if (ul_chan && ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
> +		return 0;
> +
> +

Remove extra newline.

> +	if (dl_chan && ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
> +		return 0;
> +
> +	if (dl_chan->pre_alloc)
> +		return mhi_prepare_for_transfer_autoqueue(mhi_dev);
> +	else
> +		return mhi_prepare_for_transfer(mhi_dev);
> +}
> +
> +int mhi_prepare_all_for_transfer(struct mhi_controller *mhi_cntrl)
> +{
> +	return device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL,
> +				     ____mhi_prepare_for_transfer);
> +}
> +EXPORT_SYMBOL_GPL(mhi_prepare_all_for_transfer);
> +
>  void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
>  {
>  	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> @@ -1684,3 +1736,58 @@ void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
>  	}
>  }
>  EXPORT_SYMBOL_GPL(mhi_unprepare_from_transfer);
> +
> +static int ____mhi_unprepare_from_transfer(struct device *dev, void *data)

__mhi_unprepare_all_from_transfer

> +{
> +	struct mhi_device *mhi_dev;
> +	struct mhi_chan *ul_chan, *dl_chan;
> +	enum mhi_ee_type ee = MHI_EE_MAX;
> +
> +	if (dev->bus != &mhi_bus_type)
> +		return 0;
> +
> +	mhi_dev = to_mhi_device(dev);
> +
> +	/* Only unprepare virtual devices that are attached to bus */
> +	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
> +		return 0;
> +
> +	/* There are cases where there is no MHI client driver matches
> +	 * this device, so it is not probed or prepared, no need to
> +	 * do unprepare for it.
> +	 */
> +	if (!mhi_dev->id)
> +		return 0;
> +
> +	ul_chan = mhi_dev->ul_chan;
> +	dl_chan = mhi_dev->dl_chan;
> +
> +	/*
> +	 * If execution environment is specified, remove only those devices that
> +	 * started in them based on ee_mask for the channels as we move on to a
> +	 * different execution environment
> +	 */
> +	if (data)
> +		ee = *(enum mhi_ee_type *)data;
> +
> +	if (ul_chan) {
> +		if (ee != MHI_EE_MAX && !(ul_chan->ee_mask & BIT(ee)))
> +			return 0;
> +	}
> +
> +	if (dl_chan) {
> +		if (ee != MHI_EE_MAX && !(dl_chan->ee_mask & BIT(ee)))
> +			return 0;
> +	}
> +
> +	mhi_unprepare_from_transfer(mhi_dev);
> +
> +	return 0;
> +}
> +
> +int mhi_unprepare_all_from_transfer(struct mhi_controller *mhi_cntrl)
> +{
> +	return device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL,
> +				     ____mhi_unprepare_from_transfer);
> +}
> +EXPORT_SYMBOL_GPL(mhi_unprepare_all_from_transfer);
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index ae092bc8b97e..dcf62a57056a 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -668,7 +668,7 @@ static inline void mhi_power_down(struct mhi_controller *mhi_cntrl, bool gracefu
>   * destroy struct devices. This is a variant for mhi_power_down() and is a
>   * workaround to make it possible to use mhi_power_up() in a resume
>   * handler. When using this variant the caller must also call
> - * mhi_prepare_all_for_transfer_autoqueue() and
> + * mhi_prepare_all_for_transfer() and

This change belongs to previous patch.

>   * mhi_unprepare_all_from_transfer().
>   *
>   * @mhi_cntrl: MHI controller
> @@ -842,4 +842,22 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, enum dma_data_direction dir,
>   */
>  bool mhi_queue_is_full(struct mhi_device *mhi_dev, enum dma_data_direction dir);
>  
> +/**
> + * mhi_prepare_all_for_transfer - if you are using
> + * mhi_power_down_no_destroy() variant this needs to be called after
> + * calling mhi_power_up().

Add info about what this API does also.

> + *
> + * @mhi_cntrl: MHI controller
> + */
> +int mhi_prepare_all_for_transfer(struct mhi_controller *mhi_cntrl);
> +
> +/**
> + * mhi_unprepare_all_from_transfer - if you are using
> + * mhi_power_down_no_destroy() variant this function needs to be called
> + * before calling mhi_power_down_no_destroy().

Same as above.

- Mani

> + *
> + * @mhi_cntrl: MHI controller
> + */
> +int mhi_unprepare_all_from_transfer(struct mhi_controller *mhi_cntrl);
> +
>  #endif /* _MHI_H_ */
> -- 
> 2.39.2
> 
> 

-- 
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