[PATCH fpga 3/9] fpga zynq: Fix incorrect ISR state on bootup

[moritz.fischer@ettus.com (Moritz Fischer)]

Hi Jason,

On Wed, Nov 9, 2016 at 2:58 PM, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> It is best practice to clear and mask all interrupts before
> associating the IRQ, and this should be done after the clock
> is enabled.
>
> This corrects a bad result from zynq_fpga_ops_state on bootup
> where left over latched values in INT_STS_OFFSET caused it to
> report an unconfigured FPGA as configured.
>
> After this change the boot up operating state for an unconfigured
> FPGA reports 'unknown'.
>
> Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
> ---
>  drivers/fpga/zynq-fpga.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
> index 86f4377e2b52..40cf0feaca7c 100644
> --- a/drivers/fpga/zynq-fpga.c
> +++ b/drivers/fpga/zynq-fpga.c
> @@ -460,13 +460,6 @@ static int zynq_fpga_probe(struct platform_device *pdev)
>                 return priv->irq;
>         }
>
> -       err = devm_request_irq(dev, priv->irq, zynq_fpga_isr, 0,
> -                              dev_name(dev), priv);
> -       if (err) {
> -               dev_err(dev, "unable to request IRQ\n");
> -               return err;
> -       }
> -
>         priv->clk = devm_clk_get(dev, "ref_clk");
>         if (IS_ERR(priv->clk)) {
>                 dev_err(dev, "input clock not found\n");
> @@ -482,6 +475,16 @@ static int zynq_fpga_probe(struct platform_device *pdev)
>         /* unlock the device */
>         zynq_fpga_write(priv, UNLOCK_OFFSET, UNLOCK_MASK);
>
> +       zynq_fpga_write(priv, INT_MASK_OFFSET, 0xFFFFFFFF);

Named constant please.

> +       zynq_fpga_write(priv, INT_STS_OFFSET, IXR_ALL_MASK);
> +       err = devm_request_irq(dev, priv->irq, zynq_fpga_isr, 0, dev_name(dev),
> +                              priv);
> +       if (err) {
> +               dev_err(dev, "unable to request IRQ\n");
> +               clk_unprepare(priv->clk);

Your enable count is off in that case. This should be a clk_disable_unprepare()
call.

<snip>

clk_prepare_enable()

if(err) {
    clk_unprepare();
    return err; /* enable count = 1? <- huh? */
}

clk_disable() enable count = 0
clk_unprepare() prepare count = 0

</snip>

> +               return err;
> +       }
> +
>         clk_disable(priv->clk);
>
>         err = fpga_mgr_register(dev, "Xilinx Zynq FPGA Manager",
> --
> 2.1.4
>

Thanks,

Moritz