Re: [PATCH 2/4] spi: sprd: Add the SPI irq function for the SPI DMA mode

Mark Brown
2019-01-15T14:25:06Z

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On Tue, Jan 15, 2019 at 09:46:51PM +0800, Baolin Wang wrote:

This looks good, just one small issue and a thing to check:

> +static irqreturn_t sprd_spi_handle_irq(int irq, void *data)
> +{
> + struct sprd_spi *ss = (struct sprd_spi *)data;
> + u32 val = readl_relaxed(ss->base + SPRD_SPI_INT_MASK_STS);
> +
> + if (val & SPRD_SPI_MASK_TX_END) {
> + writel_relaxed(SPRD_SPI_TX_END_CLR, ss->base + SPRD_SPI_INT_CLR);
> + if (!(ss->trans_mode & SPRD_SPI_RX_MODE))
> + complete(&ss->xfer_completion);
> + return IRQ_HANDLED;
> + }
> +
> + if (val & SPRD_SPI_MASK_RX_END) {
> + writel_relaxed(SPRD_SPI_RX_END_CLR, ss->base + SPRD_SPI_INT_CLR);
> + complete(&ss->xfer_completion);
> + }
> +
> + return IRQ_HANDLED;
> +}

This will return IRQ_HANDLED no matter if there was an interrupt
actually handled. That means that if something goes wrong due to some
bug or a hardware change (eg, a new version of the IP) and there's
another interrupt fired we won't clear it and the interrupt core won't
be able to detect that it's a spurious interrupt and use its own error
handling. It's better to return IRQ_NONE in that case.

> + ret = devm_request_irq(&pdev->dev, ss->irq, sprd_spi_handle_irq,
> + 0, pdev->name, ss);
> + if (ret)
> + dev_err(&pdev->dev, "failed to request spi irq %d, ret = %d\n",
> + ss->irq, ret);

Are you sure it's safe to use devm_request_irq(), especially when
unloading the driver? Using it means that we will only disable the
interrupt after the driver's remove function has finished so there's a
danger of an interrupt firing when some of the resources the hander has
used are still in use. I didn't spot any issues, just something to
check especially with the later patches building on top of this.

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