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

Sricharan R
2017-06-14T07:27:35Z

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