linux-kernel - Re: [PATCH v2] bus: mhi: core: Add support for processing priority of event ring

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Date:   Sat, 19 Jun 2021 09:59:36 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Bhaumik Bhatt <bbhatt@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        loic.poulain@...aro.org
Subject: Re: [PATCH v2] bus: mhi: core: Add support for processing priority
 of event ring

On Fri, Jun 18, 2021 at 03:05:03PM -0700, Bhaumik Bhatt wrote:
> From: Hemant Kumar <hemantk@...eaurora.org>
> 
> Event ring priorities are currently set to 1 and are unused.
> Default processing priority for event rings is set to regular
> tasklet. Controllers can choose to use high priority tasklet
> scheduling for certain event rings critical for processing such
> as ones transporting control information if they wish to avoid
> system scheduling delays for those packets. In order to support
> these use cases, allow controllers to set event ring priority to
> high.
> 
> Signed-off-by: Hemant Kumar <hemantk@...eaurora.org>
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/init.c | 3 +--
>  drivers/bus/mhi/core/main.c | 9 +++++++--
>  include/linux/mhi.h         | 2 +-
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index c81b377..4446760 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -673,8 +673,7 @@ static int parse_ev_cfg(struct mhi_controller *mhi_cntrl,
>  				&mhi_cntrl->mhi_chan[mhi_event->chan];
>  		}
>  
> -		/* Priority is fixed to 1 for now */
> -		mhi_event->priority = 1;
> +		mhi_event->priority = event_cfg->priority;
>  
>  		mhi_event->db_cfg.brstmode = event_cfg->mode;
>  		if (MHI_INVALID_BRSTMODE(mhi_event->db_cfg.brstmode))
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 8ac73f9..3775c77 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -454,10 +454,15 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev)
>  
>  		if (mhi_dev)
>  			mhi_notify(mhi_dev, MHI_CB_PENDING_DATA);
> -	} else {
> -		tasklet_schedule(&mhi_event->task);
> +
> +		return IRQ_HANDLED;
>  	}
>  
> +	if (!mhi_event->priority)
> +		tasklet_hi_schedule(&mhi_event->task);
> +	else
> +		tasklet_schedule(&mhi_event->task);
> +
>  	return IRQ_HANDLED;
>  }
>  
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index 86cea52..bf23c21 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -250,7 +250,7 @@ struct mhi_channel_config {
>   * @irq_moderation_ms: Delay irq for additional events to be aggregated
>   * @irq: IRQ associated with this ring
>   * @channel: Dedicated channel number. U32_MAX indicates a non-dedicated ring
> - * @priority: Priority of this ring. Use 1 for now
> + * @priority: Processing priority of this ring. 0 is high and 1 is regular
>   * @mode: Doorbell mode
>   * @data_type: Type of data this ring will process
>   * @hardware_event: This ring is associated with hardware channels
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>