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[PATCH 11/18] spi: qup: properly detect extra interrupts

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  [PATCH 11/18] spi: qup: properly detect extra interrupts Varadarajan Narayanan <varada@codeaurora.org> - 2017-06-14 08:00 +0200
    Re: [PATCH 11/18] spi: qup: properly detect extra interrupts Sricharan R <sricharan@codeaurora.org> - 2017-06-14 09:30 +0200
      Re: [PATCH 11/18] spi: qup: properly detect extra interrupts Andy Gross <andy.gross@linaro.org> - 2017-06-14 22:10 +0200
        Re: [PATCH 11/18] spi: qup: properly detect extra interrupts Matthew McClintock <mmcclint@codeaurora.org> - 2017-06-15 00:00 +0200
        Re: [PATCH 11/18] spi: qup: properly detect extra interrupts Sricharan R <sricharan@codeaurora.org> - 2017-06-15 07:30 +0200

#1665451 — [PATCH 11/18] spi: qup: properly detect extra interrupts

It's possible for a SPI transaction to complete and get another
interrupt and have it processed on the same spi_transfer before the
transfer_one can set it to NULL.

This masks unexpected interrupts, so let's set the spi_transfer to
NULL in the interrupt once the transaction is done. So we can
properly detect these bad interrupts and print warning messages.

Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
---
 drivers/spi/spi-qup.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
index bd53e82..1a2a9d9 100644
--- a/drivers/spi/spi-qup.c
+++ b/drivers/spi/spi-qup.c
@@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 	struct spi_qup *controller = dev_id;
 	struct spi_transfer *xfer;
 	u32 opflags, qup_err, spi_err;
-	unsigned long flags;
 	int error = 0;
+	bool done = 0;
 
-	spin_lock_irqsave(&controller->lock, flags);
+	spin_lock(&controller->lock);
 	xfer = controller->xfer;
 	controller->xfer = NULL;
-	spin_unlock_irqrestore(&controller->lock, flags);
+	spin_unlock(&controller->lock);
 
 	qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
 	spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
@@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
 			spi_qup_write(controller, xfer);
 	}
 
-	spin_lock_irqsave(&controller->lock, flags);
-	controller->error = error;
-	controller->xfer = xfer;
-	spin_unlock_irqrestore(&controller->lock, flags);
-
 	/* re-read opflags as flags may have changed due to actions above */
 	opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
 
 	if ((controller->rx_bytes == xfer->len &&
 		(opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
+		done = true;
+
+	spin_lock(&controller->lock);
+	controller->error = error;
+	controller->xfer = done ? NULL : xfer;
+	spin_unlock(&controller->lock);
+
+	if (done)
 		complete(&controller->done);
 
 	return IRQ_HANDLED;
@@ -765,7 +768,6 @@ static int spi_qup_transfer_one(struct spi_master *master,
 exit:
 	spi_qup_set_state(controller, QUP_STATE_RESET);
 	spin_lock_irqsave(&controller->lock, flags);
-	controller->xfer = NULL;
 	if (!ret)
 		ret = controller->error;
 	spin_unlock_irqrestore(&controller->lock, flags);
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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#1665511

Hi Varada,

On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:
> It's possible for a SPI transaction to complete and get another
> interrupt and have it processed on the same spi_transfer before the
> transfer_one can set it to NULL.
> 
> This masks unexpected interrupts, so let's set the spi_transfer to
> NULL in the interrupt once the transaction is done. So we can
> properly detect these bad interrupts and print warning messages.
> 
> Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
> Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
> ---
>  drivers/spi/spi-qup.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
> index bd53e82..1a2a9d9 100644
> --- a/drivers/spi/spi-qup.c
> +++ b/drivers/spi/spi-qup.c
> @@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>  	struct spi_qup *controller = dev_id;
>  	struct spi_transfer *xfer;
>  	u32 opflags, qup_err, spi_err;
> -	unsigned long flags;
>  	int error = 0;
> +	bool done = 0;
>  
> -	spin_lock_irqsave(&controller->lock, flags);
> +	spin_lock(&controller->lock);
>  	xfer = controller->xfer;
>  	controller->xfer = NULL;
> -	spin_unlock_irqrestore(&controller->lock, flags);
> +	spin_unlock(&controller->lock);

 Why change the locking here ?

>  
>  	qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
>  	spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
> @@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>  			spi_qup_write(controller, xfer);
>  	}
>  
> -	spin_lock_irqsave(&controller->lock, flags);
> -	controller->error = error;
> -	controller->xfer = xfer;
> -	spin_unlock_irqrestore(&controller->lock, flags);
> -
>  	/* re-read opflags as flags may have changed due to actions above */
>  	opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
>  
>  	if ((controller->rx_bytes == xfer->len &&
>  		(opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
> +		done = true;
> +
> +	spin_lock(&controller->lock);
> +	controller->error = error;
> +	controller->xfer = done ? NULL : xfer;
> +	spin_unlock(&controller->lock);
> +
> +	if (done)
>  		complete(&controller->done);
>  
  Its not clear, why the driver is setting the controller->xfer = NULL
  and restoring it inside the irq. This patch seems to fix things on
  top of that.

Regards,
 Sricharan

-- 
"QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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#1666186

On Wed, Jun 14, 2017 at 12:57:25PM +0530, Sricharan R wrote:
> Hi Varada,
> 
> On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:
> > It's possible for a SPI transaction to complete and get another
> > interrupt and have it processed on the same spi_transfer before the
> > transfer_one can set it to NULL.
> > 
> > This masks unexpected interrupts, so let's set the spi_transfer to
> > NULL in the interrupt once the transaction is done. So we can
> > properly detect these bad interrupts and print warning messages.
> > 
> > Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
> > Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
> > ---
> >  drivers/spi/spi-qup.c | 20 +++++++++++---------
> >  1 file changed, 11 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
> > index bd53e82..1a2a9d9 100644
> > --- a/drivers/spi/spi-qup.c
> > +++ b/drivers/spi/spi-qup.c
> > @@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
> >  	struct spi_qup *controller = dev_id;
> >  	struct spi_transfer *xfer;
> >  	u32 opflags, qup_err, spi_err;
> > -	unsigned long flags;
> >  	int error = 0;
> > +	bool done = 0;
> >  
> > -	spin_lock_irqsave(&controller->lock, flags);
> > +	spin_lock(&controller->lock);
> >  	xfer = controller->xfer;
> >  	controller->xfer = NULL;
> > -	spin_unlock_irqrestore(&controller->lock, flags);
> > +	spin_unlock(&controller->lock);
> 
>  Why change the locking here ?
> 
> >  
> >  	qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
> >  	spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
> > @@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
> >  			spi_qup_write(controller, xfer);
> >  	}
> >  
> > -	spin_lock_irqsave(&controller->lock, flags);
> > -	controller->error = error;
> > -	controller->xfer = xfer;
> > -	spin_unlock_irqrestore(&controller->lock, flags);
> > -
> >  	/* re-read opflags as flags may have changed due to actions above */
> >  	opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
> >  
> >  	if ((controller->rx_bytes == xfer->len &&
> >  		(opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
> > +		done = true;
> > +
> > +	spin_lock(&controller->lock);
> > +	controller->error = error;
> > +	controller->xfer = done ? NULL : xfer;
> > +	spin_unlock(&controller->lock);
> > +
> > +	if (done)
> >  		complete(&controller->done);
> >  
>   Its not clear, why the driver is setting the controller->xfer = NULL
>   and restoring it inside the irq. This patch seems to fix things on
>   top of that.

I think the original intent was to make sure that the irqhandler knew that there
was no outstanding transaction.  This begs the question of why that would ever
be necessary.  I think it would suffice to rework all of that to remove that
behavior and perhaps enable/disable the irq as we need to during transactions.

I've never been a fan of the controller->xfer being set to NULL.


Regards,

Andy

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#1666255

On Wed, Jun 14, 2017 at 2:59 PM, Andy Gross <andy.gross@linaro.org> wrote:
> On Wed, Jun 14, 2017 at 12:57:25PM +0530, Sricharan R wrote:
>> Hi Varada,
>>
>> On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:
>> > It's possible for a SPI transaction to complete and get another
>> > interrupt and have it processed on the same spi_transfer before the
>> > transfer_one can set it to NULL.
>> >
>> > This masks unexpected interrupts, so let's set the spi_transfer to
>> > NULL in the interrupt once the transaction is done. So we can
>> > properly detect these bad interrupts and print warning messages.
>> >
>> > Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
>> > Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
>> > ---
>> >  drivers/spi/spi-qup.c | 20 +++++++++++---------
>> >  1 file changed, 11 insertions(+), 9 deletions(-)
>> >
>> > diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
>> > index bd53e82..1a2a9d9 100644
>> > --- a/drivers/spi/spi-qup.c
>> > +++ b/drivers/spi/spi-qup.c
>> > @@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>> >     struct spi_qup *controller = dev_id;
>> >     struct spi_transfer *xfer;
>> >     u32 opflags, qup_err, spi_err;
>> > -   unsigned long flags;
>> >     int error = 0;
>> > +   bool done = 0;
>> >
>> > -   spin_lock_irqsave(&controller->lock, flags);
>> > +   spin_lock(&controller->lock);
>> >     xfer = controller->xfer;
>> >     controller->xfer = NULL;
>> > -   spin_unlock_irqrestore(&controller->lock, flags);
>> > +   spin_unlock(&controller->lock);
>>
>>  Why change the locking here ?
>>
>> >
>> >     qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
>> >     spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
>> > @@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>> >                     spi_qup_write(controller, xfer);
>> >     }
>> >
>> > -   spin_lock_irqsave(&controller->lock, flags);
>> > -   controller->error = error;
>> > -   controller->xfer = xfer;
>> > -   spin_unlock_irqrestore(&controller->lock, flags);
>> > -
>> >     /* re-read opflags as flags may have changed due to actions above */
>> >     opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
>> >
>> >     if ((controller->rx_bytes == xfer->len &&
>> >             (opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
>> > +           done = true;
>> > +
>> > +   spin_lock(&controller->lock);
>> > +   controller->error = error;
>> > +   controller->xfer = done ? NULL : xfer;
>> > +   spin_unlock(&controller->lock);
>> > +
>> > +   if (done)
>> >             complete(&controller->done);
>> >
>>   Its not clear, why the driver is setting the controller->xfer = NULL
>>   and restoring it inside the irq. This patch seems to fix things on
>>   top of that.
>
> I think the original intent was to make sure that the irqhandler knew that there
> was no outstanding transaction.  This begs the question of why that would ever
> be necessary.  I think it would suffice to rework all of that to remove that
> behavior and perhaps enable/disable the irq as we need to during transactions.
>
> I've never been a fan of the controller->xfer being set to NULL.

Also, this patch presumably fixes an issue seen on Dakota SoCs,
doesn't add or remote the NULL bits.

-M

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#1666470

Hi Andy,

On 6/15/2017 1:29 AM, Andy Gross wrote:
> On Wed, Jun 14, 2017 at 12:57:25PM +0530, Sricharan R wrote:
>> Hi Varada,
>>
>> On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:
>>> It's possible for a SPI transaction to complete and get another
>>> interrupt and have it processed on the same spi_transfer before the
>>> transfer_one can set it to NULL.
>>>
>>> This masks unexpected interrupts, so let's set the spi_transfer to
>>> NULL in the interrupt once the transaction is done. So we can
>>> properly detect these bad interrupts and print warning messages.
>>>
>>> Signed-off-by: Matthew McClintock <mmcclint@codeaurora.org>
>>> Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
>>> ---
>>>  drivers/spi/spi-qup.c | 20 +++++++++++---------
>>>  1 file changed, 11 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
>>> index bd53e82..1a2a9d9 100644
>>> --- a/drivers/spi/spi-qup.c
>>> +++ b/drivers/spi/spi-qup.c
>>> @@ -496,13 +496,13 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>>>  	struct spi_qup *controller = dev_id;
>>>  	struct spi_transfer *xfer;
>>>  	u32 opflags, qup_err, spi_err;
>>> -	unsigned long flags;
>>>  	int error = 0;
>>> +	bool done = 0;
>>>  
>>> -	spin_lock_irqsave(&controller->lock, flags);
>>> +	spin_lock(&controller->lock);
>>>  	xfer = controller->xfer;
>>>  	controller->xfer = NULL;
>>> -	spin_unlock_irqrestore(&controller->lock, flags);
>>> +	spin_unlock(&controller->lock);
>>
>>  Why change the locking here ?
>>
>>>  
>>>  	qup_err = readl_relaxed(controller->base + QUP_ERROR_FLAGS);
>>>  	spi_err = readl_relaxed(controller->base + SPI_ERROR_FLAGS);
>>> @@ -556,16 +556,19 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>>>  			spi_qup_write(controller, xfer);
>>>  	}
>>>  
>>> -	spin_lock_irqsave(&controller->lock, flags);
>>> -	controller->error = error;
>>> -	controller->xfer = xfer;
>>> -	spin_unlock_irqrestore(&controller->lock, flags);
>>> -
>>>  	/* re-read opflags as flags may have changed due to actions above */
>>>  	opflags = readl_relaxed(controller->base + QUP_OPERATIONAL);
>>>  
>>>  	if ((controller->rx_bytes == xfer->len &&
>>>  		(opflags & QUP_OP_MAX_INPUT_DONE_FLAG)) ||  error)
>>> +		done = true;
>>> +
>>> +	spin_lock(&controller->lock);
>>> +	controller->error = error;
>>> +	controller->xfer = done ? NULL : xfer;
>>> +	spin_unlock(&controller->lock);
>>> +
>>> +	if (done)
>>>  		complete(&controller->done);
>>>  
>>   Its not clear, why the driver is setting the controller->xfer = NULL
>>   and restoring it inside the irq. This patch seems to fix things on
>>   top of that.
> 
> I think the original intent was to make sure that the irqhandler knew that there
> was no outstanding transaction.  This begs the question of why that would ever
> be necessary.  I think it would suffice to rework all of that to remove that
> behavior and perhaps enable/disable the irq as we need to during transactions.
> 
> I've never been a fan of the controller->xfer being set to NULL.

 Agree, that part needs fixing in the original code. Also patch #10 changing the
 behavior to acknowledge the interrupts only when its spurious does not look
 correct. Trying to fix the original should simplify or avoid the spurious case
 itself.

Regards,
 Sricharan 

-- 
"QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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