Re: [PATCH v2] bus: mhi: core: Add an API for auto queueing buffers for DL channel

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

On Tue, Dec 07, 2021 at 12:43:39PM +0530, Manivannan Sadhasivam wrote:
> Add a new API "mhi_prepare_for_transfer_autoqueue" for using with client
> drivers like QRTR to request MHI core to autoqueue buffers for the DL
> channel along with starting both UL and DL channels.
> 
> So far, the "auto_queue" flag specified by the controller drivers in
> channel definition served this purpose but this will be removed at some
> point in future.
> 
> Cc: netdev@vger.kernel.org
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: David S. Miller <davem@davemloft.net>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Co-developed-by: Loic Poulain <loic.poulain@linaro.org>
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> 
> Changes in v2:
> 
> * Rebased on top of 5.16-rc1
> * Fixed an issue reported by kernel test bot
> * CCed netdev folks and Greg

Dave, Jakub, this patch should go through the MHI tree. Since it touches the
QRTR driver, can you please give an ACK?

Thanks,
Mani

> * Slight change to the commit subject for reflecting "core" sub-directory
> 
>  drivers/bus/mhi/core/internal.h |  6 +++++-
>  drivers/bus/mhi/core/main.c     | 21 +++++++++++++++++----
>  include/linux/mhi.h             | 21 ++++++++++++++++-----
>  net/qrtr/mhi.c                  |  2 +-
>  4 files changed, 39 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
> index 9d72b1d1e986..e2e10474a9d9 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -682,8 +682,12 @@ void mhi_deinit_free_irq(struct mhi_controller *mhi_cntrl);
>  void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
>  		      struct image_info *img_info);
>  void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl);
> +
> +/* Automatically allocate and queue inbound buffers */
> +#define MHI_CH_INBOUND_ALLOC_BUFS BIT(0)
>  int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
> -			struct mhi_chan *mhi_chan);
> +			struct mhi_chan *mhi_chan, unsigned int flags);
> +
>  int mhi_init_chan_ctxt(struct mhi_controller *mhi_cntrl,
>  		       struct mhi_chan *mhi_chan);
>  void mhi_deinit_chan_ctxt(struct mhi_controller *mhi_cntrl,
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 930aba666b67..ffde617f93a3 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1430,7 +1430,7 @@ static void mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
>  }
>  
>  int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
> -			struct mhi_chan *mhi_chan)
> +			struct mhi_chan *mhi_chan, unsigned int flags)
>  {
>  	int ret = 0;
>  	struct device *dev = &mhi_chan->mhi_dev->dev;
> @@ -1455,6 +1455,9 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
>  	if (ret)
>  		goto error_pm_state;
>  
> +	if (mhi_chan->dir == DMA_FROM_DEVICE)
> +		mhi_chan->pre_alloc = !!(flags & MHI_CH_INBOUND_ALLOC_BUFS);
> +
>  	/* Pre-allocate buffer for xfer ring */
>  	if (mhi_chan->pre_alloc) {
>  		int nr_el = get_nr_avail_ring_elements(mhi_cntrl,
> @@ -1610,8 +1613,7 @@ void mhi_reset_chan(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan)
>  	read_unlock_bh(&mhi_cntrl->pm_lock);
>  }
>  
> -/* Move channel to start state */
> -int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
> +static int __mhi_prepare_for_transfer(struct mhi_device *mhi_dev, unsigned int flags)
>  {
>  	int ret, dir;
>  	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> @@ -1622,7 +1624,7 @@ int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
>  		if (!mhi_chan)
>  			continue;
>  
> -		ret = mhi_prepare_channel(mhi_cntrl, mhi_chan);
> +		ret = mhi_prepare_channel(mhi_cntrl, mhi_chan, flags);
>  		if (ret)
>  			goto error_open_chan;
>  	}
> @@ -1640,8 +1642,19 @@ int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
>  
>  	return ret;
>  }
> +
> +int mhi_prepare_for_transfer(struct mhi_device *mhi_dev)
> +{
> +	return __mhi_prepare_for_transfer(mhi_dev, 0);
> +}
>  EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer);
>  
> +int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev)
> +{
> +	return __mhi_prepare_for_transfer(mhi_dev, MHI_CH_INBOUND_ALLOC_BUFS);
> +}
> +EXPORT_SYMBOL_GPL(mhi_prepare_for_transfer_autoqueue);
> +
>  void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev)
>  {
>  	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 723985879035..271db1d6da85 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -717,15 +717,26 @@ void mhi_device_put(struct mhi_device *mhi_dev);
>  
>  /**
>   * mhi_prepare_for_transfer - Setup UL and DL channels for data transfer.
> - *                            Allocate and initialize the channel context and
> - *                            also issue the START channel command to both
> - *                            channels. Channels can be started only if both
> - *                            host and device execution environments match and
> - *                            channels are in a DISABLED state.
>   * @mhi_dev: Device associated with the channels
> + *
> + * Allocate and initialize the channel context and also issue the START channel
> + * command to both channels. Channels can be started only if both host and
> + * device execution environments match and channels are in a DISABLED state.
>   */
>  int mhi_prepare_for_transfer(struct mhi_device *mhi_dev);
>  
> +/**
> + * mhi_prepare_for_transfer_autoqueue - Setup UL and DL channels with auto queue
> + *                                      buffers for DL traffic
> + * @mhi_dev: Device associated with the channels
> + *
> + * Allocate and initialize the channel context and also issue the START channel
> + * command to both channels. Channels can be started only if both host and
> + * device execution environments match and channels are in a DISABLED state.
> + * The MHI core will automatically allocate and queue buffers for the DL traffic.
> + */
> +int mhi_prepare_for_transfer_autoqueue(struct mhi_device *mhi_dev);
> +
>  /**
>   * mhi_unprepare_from_transfer - Reset UL and DL channels for data transfer.
>   *                               Issue the RESET channel command and let the
> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
> index fa611678af05..18196e1c8c2f 100644
> --- a/net/qrtr/mhi.c
> +++ b/net/qrtr/mhi.c
> @@ -79,7 +79,7 @@ static int qcom_mhi_qrtr_probe(struct mhi_device *mhi_dev,
>  	int rc;
>  
>  	/* start channels */
> -	rc = mhi_prepare_for_transfer(mhi_dev);
> +	rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
>  	if (rc)
>  		return rc;
>  
> -- 
> 2.25.1
>