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 17:28:45 -0700
From:   Hemant Kumar <hemantk@...eaurora.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.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

Hi Mani,

On 5/11/20 11:53 PM, Manivannan Sadhasivam wrote:
> 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.
Original code is using write_lock to protect pm_state as well as 
mhi_cntrl->ee. This patch is keeping the lock same as original code. 
Just if condition logic is negated here due to that write_unlock_irq is 
added under if condition.
> 
>> +		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

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project