linux-kernel - Re: [PATCH v1 3/5] bus: mhi: core: Skip handling BHI irq if MHI reg access is not allowed

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Date:   Tue, 12 May 2020 12:23:49 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Hemant Kumar <hemantk@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        jhugo@...eaurora.org, bbhatt@...eaurora.org
Subject: Re: [PATCH v1 3/5] bus: mhi: core: Skip handling BHI irq if MHI reg
 access is not allowed

On Mon, May 11, 2020 at 07:03:07PM -0700, Hemant Kumar wrote:
> Driver continues handling of BHI interrupt even if MHI register access
> is not allowed. By doing so it calls the status call back and performs
> early notification for the MHI client. This is not needed when MHI
> register access is not allowed. Hence skip the handling in this case and
> return. Also add debug log to print device state, local EE and device EE
> when reg access is valid.
> 
> Signed-off-by: Hemant Kumar <hemantk@...eaurora.org>
> Reviewed-by: Jeffrey Hugo <jhugo@...eaurora.org>
> ---
>  drivers/bus/mhi/core/main.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 9ec9b36..467c0ba 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -369,22 +369,29 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev)
>  	return IRQ_HANDLED;
>  }
>  
> -irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *dev)
> +irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
>  {
> -	struct mhi_controller *mhi_cntrl = dev;
> +	struct mhi_controller *mhi_cntrl = priv;
> +	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>  	enum mhi_state state = MHI_STATE_MAX;
>  	enum mhi_pm_state pm_state = 0;
>  	enum mhi_ee_type ee = 0;
>  
>  	write_lock_irq(&mhi_cntrl->pm_lock);
> -	if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> -		state = mhi_get_mhi_state(mhi_cntrl);
> -		ee = mhi_cntrl->ee;
> -		mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
> +	if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> +		write_unlock_irq(&mhi_cntrl->pm_lock);

write_lock is only used for protecting 'mhi_cntrl->ee' but here we are not
updating it if reg access is not valid. So there is no reason to hold this lock.

> +		goto exit_intvec;
>  	}
>  
> +	state = mhi_get_mhi_state(mhi_cntrl);
> +	ee = mhi_cntrl->ee;
> +	mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);

But it is needed here.

Thanks,
Mani

> +	dev_dbg(dev, "local ee:%s device ee:%s dev_state:%s\n",
> +		TO_MHI_EXEC_STR(mhi_cntrl->ee), TO_MHI_EXEC_STR(ee),
> +		TO_MHI_STATE_STR(state));
> +
>  	if (state == MHI_STATE_SYS_ERR) {
> -		dev_dbg(&mhi_cntrl->mhi_dev->dev, "System error detected\n");
> +		dev_dbg(dev, "System error detected\n");
>  		pm_state = mhi_tryset_pm_state(mhi_cntrl,
>  					       MHI_PM_SYS_ERR_DETECT);
>  	}
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project