linux-kernel - Re: [PATCH 10/18] spi: qup: Fix DMA mode interrupt handling

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Date:   Thu, 15 Jun 2017 11:22:10 +0530
From:   Sricharan R <sricharan@...eaurora.org>
To:     Andy Gross <andy.gross@...aro.org>
Cc:     Varadarajan Narayanan <varada@...eaurora.org>, broonie@...nel.org,
        robh+dt@...nel.org, mark.rutland@....com, david.brown@...aro.org,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org
Subject: Re: [PATCH 10/18] spi: qup: Fix DMA mode interrupt handling

Hi Andy,

On 6/15/2017 1:36 AM, Andy Gross wrote:
> On Wed, Jun 14, 2017 at 12:51:11PM +0530, Sricharan R wrote:
>> Hi Varada,
>>
>> On 6/14/2017 11:22 AM, Varadarajan Narayanan wrote:
>>> This is needed for v1, where the i/o completion is not
>>> handled in the dma driver.
>>>
>>> Signed-off-by: Andy Gross <andy.gross@...aro.org>
>>> Signed-off-by: Varadarajan Narayanan <varada@...eaurora.org>
>>> ---
>>>  drivers/spi/spi-qup.c | 15 +++++++++++++--
>>>  1 file changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/spi/spi-qup.c b/drivers/spi/spi-qup.c
>>> index 872de28..bd53e82 100644
>>> --- a/drivers/spi/spi-qup.c
>>> +++ b/drivers/spi/spi-qup.c
>>> @@ -510,9 +510,9 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>>>  
>>>  	writel_relaxed(qup_err, controller->base + QUP_ERROR_FLAGS);
>>>  	writel_relaxed(spi_err, controller->base + SPI_ERROR_FLAGS);
>>> -	writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
>>>  
>>>  	if (!xfer) {
>>> +		writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
>>
>>  This does look correct to remove acknowledging the QUP in normal case and
>>   do it conditionally only when xfer = NULL.
> 
> This is to probably mask the issue of getting erroneous/spurious IRQs.
> 

 hmm, now the QUP_OPERATIONAL is not written to acknowledge the interrupts in
 normal case seems to be wrong.

>>
>>>  		dev_err_ratelimited(controller->dev, "unexpected irq %08x %08x %08x\n",
>>>  				    qup_err, spi_err, opflags);
>>>  		return IRQ_HANDLED;
>>> @@ -540,7 +540,15 @@ static irqreturn_t spi_qup_qup_irq(int irq, void *dev_id)
>>>  		error = -EIO;
>>>  	}
>>>  
>>> -	if (!spi_qup_is_dma_xfer(controller->mode)) {
>>> +	if (spi_qup_is_dma_xfer(controller->mode)) {
>>> +		writel_relaxed(opflags, controller->base + QUP_OPERATIONAL);
>>> +		if (opflags & QUP_OP_IN_SERVICE_FLAG &&
>>> +		    opflags & QUP_OP_MAX_INPUT_DONE_FLAG)
>>> +			complete(&controller->rxc);
>>> +		if (opflags & QUP_OP_OUT_SERVICE_FLAG &&
>>> +		    opflags & QUP_OP_MAX_OUTPUT_DONE_FLAG)
>>> +			complete(&controller->txc);
>>> +	} else {
>>
>>  Is this because in patch #8 that we do not populate the dma callback
>>  for v1. If that is done, this should not be required at all, as the
>>  complete would be signalled from the dma callback.
> 
> I believe that is true.  There shouldn't be any IRQs for DMA enabled
> transactions (at least BAM-dma).

 yeah, the above hunk looks like is ADM specific, not sure why ADM cannot
 work with dma callbacks.

Regards,
 Sricharan

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