Re: [PATCH 1/2] spi: pxa2xx: Prepare for edge-triggered interrupts

Andy Shevchenko
2017-01-16T09:25:41Z

On Mon, 2017-01-16 at 10:05 +0100, Jan Kiszka wrote:
> When using the a device with edge-triggered interrupts, such as MSIs,
> the interrupt handler has to ensure that there is a point in time
> during
> its execution where all interrupts sources are silent so that a new
> event can trigger a new interrupt again.
>
> This is achieved here by looping over SSSR evaluation. We need to take
> into account that SSCR1 may be changed by the transfer handler, thus
> we
> need to redo the mask calculation, at least regarding the volatile
> interrupt enable bit (TIE).

Could you split this to two patches, one just move the code under
question to a helper function (no functional change), the other does
what you state in commit message here?

>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  drivers/spi/spi-pxa2xx.c | 50 +++++++++++++++++++++++++++----------
> -----------
>  1 file changed, 28 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
> index dd7b5b4..24bf549 100644
> --- a/drivers/spi/spi-pxa2xx.c
> +++ b/drivers/spi/spi-pxa2xx.c
> @@ -737,6 +737,7 @@ static irqreturn_t ssp_int(int irq, void *dev_id)
>   struct driver_data *drv_data = dev_id;
>   u32 sccr1_reg;
>   u32 mask = drv_data->mask_sr;
> + irqreturn_t ret = IRQ_NONE;
>   u32 status;
>
>   /*
> @@ -760,37 +761,42 @@ static irqreturn_t ssp_int(int irq, void
> *dev_id)
>
>   sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1);
>
> - /* Ignore possible writes if we don't need to write */
> - if (!(sccr1_reg & SSCR1_TIE))
> - mask &= ~SSSR_TFS;
> -
>   /* Ignore RX timeout interrupt if it is disabled */
>   if (!(sccr1_reg & SSCR1_TINTE))
>   mask &= ~SSSR_TINT;
>
> - if (!(status & mask))
> - return IRQ_NONE;
> + while (1) {
> + /* Ignore possible writes if we don't need to write
> */
> + if (!(sccr1_reg & SSCR1_TIE))
> + mask &= ~SSSR_TFS;
>
> - if (!drv_data->master->cur_msg) {
> + if (!(status & mask))
> + return ret;
>
> - pxa2xx_spi_write(drv_data, SSCR0,
> -  pxa2xx_spi_read(drv_data, SSCR0)
> -  & ~SSCR0_SSE);
> - pxa2xx_spi_write(drv_data, SSCR1,
> -  pxa2xx_spi_read(drv_data, SSCR1)
> -  & ~drv_data->int_cr1);
> - if (!pxa25x_ssp_comp(drv_data))
> - pxa2xx_spi_write(drv_data, SSTO, 0);
> - write_SSSR_CS(drv_data, drv_data->clear_sr);
> + if (!drv_data->master->cur_msg) {
>
> - dev_err(&drv_data->pdev->dev,
> - "bad message state in interrupt handler\n");
> + pxa2xx_spi_write(drv_data, SSCR0,
> +  pxa2xx_spi_read(drv_data,
> SSCR0)
> +  & ~SSCR0_SSE);
> + pxa2xx_spi_write(drv_data, SSCR1,
> +  pxa2xx_spi_read(drv_data,
> SSCR1)
> +  & ~drv_data->int_cr1);
> + if (!pxa25x_ssp_comp(drv_data))
> + pxa2xx_spi_write(drv_data, SSTO, 0);
> + write_SSSR_CS(drv_data, drv_data->clear_sr);
>
> - /* Never fail */
> - return IRQ_HANDLED;
> - }
> + dev_err(&drv_data->pdev->dev,
> + "bad message state in interrupt
> handler\n");
>
> - return drv_data->transfer_handler(drv_data);
> + /* Never fail */
> + return IRQ_HANDLED;
> + }
> +
> + ret |= drv_data->transfer_handler(drv_data);
> +
> + status = pxa2xx_spi_read(drv_data, SSSR);
> + sccr1_reg = pxa2xx_spi_read(drv_data, SSCR1);
> + }
>  }
>
>  /*

--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy