[PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[Asutosh Das]

From: Venkat Gopalakrishnan <venkatg@codeaurora.org>

As multiple requests are submitted to the ufs host controller in
parallel there could be instances where the command completion
interrupt arrives later for a request that is already processed
earlier as the corresponding doorbell was cleared when handling
the previous interrupt. Read the interrupt status in a loop after
processing the received interrupt to catch such interrupts and
handle it.

Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 8af2af3..58d81de 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -5357,19 +5357,30 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
 	u32 intr_status, enabled_intr_status;
 	irqreturn_t retval = IRQ_NONE;
 	struct ufs_hba *hba = __hba;
+	int retries = hba->nutrs;
 
 	spin_lock(hba->host->host_lock);
 	intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
-	enabled_intr_status =
-		intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
 
-	if (intr_status)
-		ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
+	/*
+	 * There could be max of hba->nutrs reqs in flight and in worst case
+	 * if the reqs get finished 1 by 1 after the interrupt status is
+	 * read, make sure we handle them by checking the interrupt status
+	 * again in a loop until we process all of the reqs before returning.
+	 */
+	do {
+		enabled_intr_status =
+			intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
+		if (intr_status)
+			ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
+		if (enabled_intr_status) {
+			ufshcd_sl_intr(hba, enabled_intr_status);
+			retval = IRQ_HANDLED;
+		}
+
+		intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
+	} while (intr_status && --retries);
 
-	if (enabled_intr_status) {
-		ufshcd_sl_intr(hba, enabled_intr_status);
-		retval = IRQ_HANDLED;
-	}
 	spin_unlock(hba->host->host_lock);
 	return retval;
 }
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

RE: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[Avri Altman]

Hi,
Can you elaborate how this can even happen?
Isn't the interrupt aggregation capability should attend for those cases?

Thanks,
Avri

> -----Original Message-----
> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> owner@vger.kernel.org] On Behalf Of Asutosh Das
> Sent: Tuesday, January 30, 2018 6:54 AM
> To: subhashj@codeaurora.org; cang@codeaurora.org;
> vivek.gautam@codeaurora.org; rnayak@codeaurora.org;
> vinholikatti@gmail.com; jejb@linux.vnet.ibm.com;
> martin.petersen@oracle.com
> Cc: linux-scsi@vger.kernel.org; Venkat Gopalakrishnan
> <venkatg@codeaurora.org>; Asutosh Das <asutoshd@codeaurora.org>; open
> list <linux-kernel@vger.kernel.org>
> Subject: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed
> 
> From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
> 
> As multiple requests are submitted to the ufs host controller in parallel there
> could be instances where the command completion interrupt arrives later for a
> request that is already processed earlier as the corresponding doorbell was
> cleared when handling the previous interrupt. Read the interrupt status in a
> loop after processing the received interrupt to catch such interrupts and handle
> it.
> 
> Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
> ---
>  drivers/scsi/ufs/ufshcd.c | 27 +++++++++++++++++++--------
>  1 file changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index
> 8af2af3..58d81de 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5357,19 +5357,30 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
>  	u32 intr_status, enabled_intr_status;
>  	irqreturn_t retval = IRQ_NONE;
>  	struct ufs_hba *hba = __hba;
> +	int retries = hba->nutrs;
> 
>  	spin_lock(hba->host->host_lock);
>  	intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
> -	enabled_intr_status =
> -		intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
> 
> -	if (intr_status)
> -		ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
> +	/*
> +	 * There could be max of hba->nutrs reqs in flight and in worst case
> +	 * if the reqs get finished 1 by 1 after the interrupt status is
> +	 * read, make sure we handle them by checking the interrupt status
> +	 * again in a loop until we process all of the reqs before returning.
> +	 */
> +	do {
> +		enabled_intr_status =
> +			intr_status & ufshcd_readl(hba,
> REG_INTERRUPT_ENABLE);
> +		if (intr_status)
> +			ufshcd_writel(hba, intr_status,
> REG_INTERRUPT_STATUS);
> +		if (enabled_intr_status) {
> +			ufshcd_sl_intr(hba, enabled_intr_status);
> +			retval = IRQ_HANDLED;
> +		}
> +
> +		intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
> +	} while (intr_status && --retries);
> 
> -	if (enabled_intr_status) {
> -		ufshcd_sl_intr(hba, enabled_intr_status);
> -		retval = IRQ_HANDLED;
> -	}
>  	spin_unlock(hba->host->host_lock);
>  	return retval;
>  }
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
> Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project.

Re: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[Asutosh Das (asd)]

On 1/31/2018 1:09 PM, Avri Altman wrote:
> Hi,
> Can you elaborate how this can even happen?
> Isn't the interrupt aggregation capability should attend for those cases?
> 
> Thanks,
> Avri
> 
>> -----Original Message-----
>> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
>> owner@vger.kernel.org] On Behalf Of Asutosh Das
>> Sent: Tuesday, January 30, 2018 6:54 AM
>> To: subhashj@codeaurora.org; cang@codeaurora.org;
>> vivek.gautam@codeaurora.org; rnayak@codeaurora.org;
>> vinholikatti@gmail.com; jejb@linux.vnet.ibm.com;
>> martin.petersen@oracle.com
>> Cc: linux-scsi@vger.kernel.org; Venkat Gopalakrishnan
>> <venkatg@codeaurora.org>; Asutosh Das <asutoshd@codeaurora.org>; open
>> list <linux-kernel@vger.kernel.org>
>> Subject: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed
>>
>> From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
>>
>> As multiple requests are submitted to the ufs host controller in parallel there
>> could be instances where the command completion interrupt arrives later for a
>> request that is already processed earlier as the corresponding doorbell was
>> cleared when handling the previous interrupt. Read the interrupt status in a
>> loop after processing the received interrupt to catch such interrupts and handle
>> it.
>>
>> Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
>> ---
>>   drivers/scsi/ufs/ufshcd.c | 27 +++++++++++++++++++--------
>>   1 file changed, 19 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index
>> 8af2af3..58d81de 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -5357,19 +5357,30 @@ static irqreturn_t ufshcd_intr(int irq, void *__hba)
>>   	u32 intr_status, enabled_intr_status;
>>   	irqreturn_t retval = IRQ_NONE;
>>   	struct ufs_hba *hba = __hba;
>> +	int retries = hba->nutrs;
>>
>>   	spin_lock(hba->host->host_lock);
>>   	intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>> -	enabled_intr_status =
>> -		intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
>>
>> -	if (intr_status)
>> -		ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
>> +	/*
>> +	 * There could be max of hba->nutrs reqs in flight and in worst case
>> +	 * if the reqs get finished 1 by 1 after the interrupt status is
>> +	 * read, make sure we handle them by checking the interrupt status
>> +	 * again in a loop until we process all of the reqs before returning.
>> +	 */
>> +	do {
>> +		enabled_intr_status =
>> +			intr_status & ufshcd_readl(hba,
>> REG_INTERRUPT_ENABLE);
>> +		if (intr_status)
>> +			ufshcd_writel(hba, intr_status,
>> REG_INTERRUPT_STATUS);
>> +		if (enabled_intr_status) {
>> +			ufshcd_sl_intr(hba, enabled_intr_status);
>> +			retval = IRQ_HANDLED;
>> +		}
>> +
>> +		intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>> +	} while (intr_status && --retries);
>>
>> -	if (enabled_intr_status) {
>> -		ufshcd_sl_intr(hba, enabled_intr_status);
>> -		retval = IRQ_HANDLED;
>> -	}
>>   	spin_unlock(hba->host->host_lock);
>>   	return retval;
>>   }
>> --
>> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
>> Inc.
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
>> Foundation Collaborative Project.
> 

Hi
yes - interrupt aggregation makes sense here. But there were some 
performance concerns with it; well, I don't have the data to back that 
up now though.
However, I can code it up and check it.
Will post it in some time.

-asd

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

Re: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[Asutosh Das (asd)]

On 2/2/2018 8:53 AM, Asutosh Das (asd) wrote:
> On 1/31/2018 1:09 PM, Avri Altman wrote:
>> Hi,
>> Can you elaborate how this can even happen?
>> Isn't the interrupt aggregation capability should attend for those cases?
>>
>> Thanks,
>> Avri
>>
>>> -----Original Message-----
>>> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
>>> owner@vger.kernel.org] On Behalf Of Asutosh Das
>>> Sent: Tuesday, January 30, 2018 6:54 AM
>>> To: subhashj@codeaurora.org; cang@codeaurora.org;
>>> vivek.gautam@codeaurora.org; rnayak@codeaurora.org;
>>> vinholikatti@gmail.com; jejb@linux.vnet.ibm.com;
>>> martin.petersen@oracle.com
>>> Cc: linux-scsi@vger.kernel.org; Venkat Gopalakrishnan
>>> <venkatg@codeaurora.org>; Asutosh Das <asutoshd@codeaurora.org>; open
>>> list <linux-kernel@vger.kernel.org>
>>> Subject: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed
>>>
>>> From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
>>>
>>> As multiple requests are submitted to the ufs host controller in 
>>> parallel there
>>> could be instances where the command completion interrupt arrives 
>>> later for a
>>> request that is already processed earlier as the corresponding 
>>> doorbell was
>>> cleared when handling the previous interrupt. Read the interrupt 
>>> status in a
>>> loop after processing the received interrupt to catch such interrupts 
>>> and handle
>>> it.
>>>
>>> Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
>>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
>>> ---
>>>   drivers/scsi/ufs/ufshcd.c | 27 +++++++++++++++++++--------
>>>   1 file changed, 19 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index
>>> 8af2af3..58d81de 100644
>>> --- a/drivers/scsi/ufs/ufshcd.c
>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>> @@ -5357,19 +5357,30 @@ static irqreturn_t ufshcd_intr(int irq, void 
>>> *__hba)
>>>       u32 intr_status, enabled_intr_status;
>>>       irqreturn_t retval = IRQ_NONE;
>>>       struct ufs_hba *hba = __hba;
>>> +    int retries = hba->nutrs;
>>>
>>>       spin_lock(hba->host->host_lock);
>>>       intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>>> -    enabled_intr_status =
>>> -        intr_status & ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
>>>
>>> -    if (intr_status)
>>> -        ufshcd_writel(hba, intr_status, REG_INTERRUPT_STATUS);
>>> +    /*
>>> +     * There could be max of hba->nutrs reqs in flight and in worst 
>>> case
>>> +     * if the reqs get finished 1 by 1 after the interrupt status is
>>> +     * read, make sure we handle them by checking the interrupt status
>>> +     * again in a loop until we process all of the reqs before 
>>> returning.
>>> +     */
>>> +    do {
>>> +        enabled_intr_status =
>>> +            intr_status & ufshcd_readl(hba,
>>> REG_INTERRUPT_ENABLE);
>>> +        if (intr_status)
>>> +            ufshcd_writel(hba, intr_status,
>>> REG_INTERRUPT_STATUS);
>>> +        if (enabled_intr_status) {
>>> +            ufshcd_sl_intr(hba, enabled_intr_status);
>>> +            retval = IRQ_HANDLED;
>>> +        }
>>> +
>>> +        intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
>>> +    } while (intr_status && --retries);
>>>
>>> -    if (enabled_intr_status) {
>>> -        ufshcd_sl_intr(hba, enabled_intr_status);
>>> -        retval = IRQ_HANDLED;
>>> -    }
>>>       spin_unlock(hba->host->host_lock);
>>>       return retval;
>>>   }
>>> -- 
>>> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
>>> Inc.
>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a 
>>> Linux
>>> Foundation Collaborative Project.
>>
> 
> Hi
> yes - interrupt aggregation makes sense here. But there were some 
> performance concerns with it; well, I don't have the data to back that 
> up now though.
> However, I can code it up and check it.
> Will post it in some time.
> 
> -asd
> 
Hi Avri,
I went through the UFS HCI - v2.1 spec. Specifically, in sec 7.2.3 it 
explicitly mentions that the software should determine if new TRs were 
completed since the interrupt status was last read/cleared. This step is 
independent of aggregation.

So I think the above implementation makes sense. Please let me know if I 
understood your concern correctly.

-asd

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

RE: [PATCH 1/1] scsi: ufs: make sure all interrupts are processed

[Avri Altman]

> >>> -----Original Message-----
> >>> From: linux-scsi-owner@vger.kernel.org [mailto:linux-scsi-
> >>> owner@vger.kernel.org] On Behalf Of Asutosh Das
> >>> Sent: Tuesday, January 30, 2018 6:54 AM
> >>> To: subhashj@codeaurora.org; cang@codeaurora.org;
> >>> vivek.gautam@codeaurora.org; rnayak@codeaurora.org;
> >>> vinholikatti@gmail.com; jejb@linux.vnet.ibm.com;
> >>> martin.petersen@oracle.com
> >>> Cc: linux-scsi@vger.kernel.org; Venkat Gopalakrishnan
> >>> <venkatg@codeaurora.org>; Asutosh Das <asutoshd@codeaurora.org>;
> >>> open list <linux-kernel@vger.kernel.org>
> >>> Subject: [PATCH 1/1] scsi: ufs: make sure all interrupts are
> >>> processed
> >>>
> >>> From: Venkat Gopalakrishnan <venkatg@codeaurora.org>
> >>>
> >>> As multiple requests are submitted to the ufs host controller in
> >>> parallel there could be instances where the command completion
> >>> interrupt arrives later for a request that is already processed
> >>> earlier as the corresponding doorbell was cleared when handling the
> >>> previous interrupt. Read the interrupt status in a loop after
> >>> processing the received interrupt to catch such interrupts and
> >>> handle it.
> >>>
> >>> Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
> >>> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Tested-by: avri.altman@wdc.com

Tested on kirin960 (mate9)  and msm8998 (htc11), both where interrupt aggregation is not allowed.

As a side note, I noticed that this patch is part of several patches, fixing some qcom-staff.
Maybe you want to put them all in a patchset?

Thanks,
Avri