linux-kernel - Re: [PATCH v6 1/4] bus: mhi: core: Add helper API to return number of free TREs

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Message-ID: <20200927031243.GD3213@Mani-XPS-13-9360>
Date:   Sun, 27 Sep 2020 08:42:43 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Hemant Kumar <hemantk@...eaurora.org>
Cc:     gregkh@...uxfoundation.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, jhugo@...eaurora.org,
        bbhatt@...eaurora.org
Subject: Re: [PATCH v6 1/4] bus: mhi: core: Add helper API to return number
 of free TREs

On Wed, Sep 16, 2020 at 12:56:04PM -0700, Hemant Kumar wrote:
> Introduce mhi_get_no_free_descriptors() API to return number
> of TREs available to queue buffer. MHI clients can use this
> API to know before hand if ring is full without calling queue
> API.
> 
> Signed-off-by: Hemant Kumar <hemantk@...eaurora.org>
> ---
>  drivers/bus/mhi/core/main.c | 12 ++++++++++++
>  include/linux/mhi.h         |  9 +++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 2cff5dd..0599e7d 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -258,6 +258,18 @@ int mhi_destroy_device(struct device *dev, void *data)
>  	return 0;
>  }
>  
> +int mhi_get_no_free_descriptors(struct mhi_device *mhi_dev,
> +				enum dma_data_direction dir)
> +{
> +	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> +	struct mhi_chan *mhi_chan = (dir == DMA_TO_DEVICE) ?
> +		mhi_dev->ul_chan : mhi_dev->dl_chan;
> +	struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
> +
> +	return get_nr_avail_ring_elements(mhi_cntrl, tre_ring);

Hmm, so this is essentially a wrapper for get_nr_avail_ring_elements().
Why can't you call this API directly?

> +}
> +EXPORT_SYMBOL_GPL(mhi_get_no_free_descriptors);
> +
>  void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason)
>  {
>  	struct mhi_driver *mhi_drv;
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index a35d876..6565528 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -600,6 +600,15 @@ void mhi_set_mhi_state(struct mhi_controller *mhi_cntrl,
>  void mhi_notify(struct mhi_device *mhi_dev, enum mhi_callback cb_reason);
>  
>  /**
> + * mhi_get_no_free_descriptors - Get transfer ring length

mhi_get_nr_free_descriptors?

> + * Get # of TD available to queue buffers
> + * @mhi_dev: Device associated with the channels
> + * @dir: Direction of the channel
> + */
> +int mhi_get_no_free_descriptors(struct mhi_device *mhi_dev,
> +				enum dma_data_direction dir);

Align enum with start of "("

Thanks,
Mani

> +
> +/**
>   * mhi_prepare_for_power_up - Do pre-initialization before power up.
>   *                            This is optional, call this before power up if
>   *                            the controller does not want bus framework to
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>