linux-kernel - Re: [PATCH v2] mhi: use irq_flags if client driver configures it

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Date:   Thu, 31 Dec 2020 12:54:04 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Carl Huang <cjhuang@...eaurora.org>
Cc:     hemantk@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, ath11k@...ts.infradead.org
Subject: Re: [PATCH v2] mhi: use irq_flags if client driver configures it

On Tue, Dec 29, 2020 at 02:05:51AM -0500, Carl Huang wrote:
> If client driver has specified the irq_flags, mhi uses this specified
> irq_flags. Otherwise, mhi uses default irq_flags.
> 
> The purpose of this change is to support one MSI vector for QCA6390.
> MHI will use one same MSI vector too in this scenario.
> 
> In case of one MSI vector, IRQ_NO_BALANCING is needed when irq handler
> is requested. The reason is if irq migration happens, the msi_data may
> change too. However, the msi_data is already programmed to QCA6390
> hardware during initialization phase. This msi_data inconsistence will
> result in crash in kernel.
> 
> Another issue is in case of one MSI vector, IRQF_NO_SUSPEND will trigger
> WARNINGS because QCA6390 wants to disable the IRQ during the suspend.
> 
> To avoid above two issues, QCA6390 driver specifies the irq_flags in case
> of one MSI vector when mhi_register_controller is called.
> 
> Signed-off-by: Carl Huang <cjhuang@...eaurora.org>

Small nitpick below, with that addressed,

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

> ---
> v2:
> - document irq_flags added to mhi_controller
> 
>  drivers/bus/mhi/core/init.c | 9 +++++++--
>  include/linux/mhi.h         | 2 ++
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index 0ffdebd..5f74e1e 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -148,12 +148,17 @@ int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
>  {
>  	struct mhi_event *mhi_event = mhi_cntrl->mhi_event;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> +	unsigned long irq_flags = IRQF_SHARED | IRQF_NO_SUSPEND;
>  	int i, ret;
>  
> +	/* if client driver has set irq_flags, use it */

s/client driver/controller driver

Thanks,
Mani

> +	if (mhi_cntrl->irq_flags)
> +		irq_flags = mhi_cntrl->irq_flags;
> +
>  	/* Setup BHI_INTVEC IRQ */
>  	ret = request_threaded_irq(mhi_cntrl->irq[0], mhi_intvec_handler,
>  				   mhi_intvec_threaded_handler,
> -				   IRQF_SHARED | IRQF_NO_SUSPEND,
> +				   irq_flags,
>  				   "bhi", mhi_cntrl);
>  	if (ret)
>  		return ret;
> @@ -171,7 +176,7 @@ int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
>  
>  		ret = request_irq(mhi_cntrl->irq[mhi_event->irq],
>  				  mhi_irq_handler,
> -				  IRQF_SHARED | IRQF_NO_SUSPEND,
> +				  irq_flags,
>  				  "mhi", mhi_event);
>  		if (ret) {
>  			dev_err(dev, "Error requesting irq:%d for ev:%d\n",
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index d4841e5..918cf6a 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -353,6 +353,7 @@ struct mhi_controller_config {
>   * @fbc_download: MHI host needs to do complete image transfer (optional)
>   * @pre_init: MHI host needs to do pre-initialization before power up
>   * @wake_set: Device wakeup set flag
> + * @irq_flags: irq flags passed to request_irq (optional)
>   *
>   * Fields marked as (required) need to be populated by the controller driver
>   * before calling mhi_register_controller(). For the fields marked as (optional)
> @@ -442,6 +443,7 @@ struct mhi_controller {
>  	bool fbc_download;
>  	bool pre_init;
>  	bool wake_set;
> +	unsigned long irq_flags;
>  };
>  
>  /**
> -- 
> 2.7.4
>