Re: [PATCH] uio/uio_pci_generic: don't fail probe if pdev->irq == NULL

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Apr 30, 2017 at 12:29:55PM -0700, Jim Harris wrote:
> Some userspace drivers and frameworks only poll and do not
> require interrupts to be available and enabled on the
> PCI device.  So remove the requirement that an IRQ is
> assigned.  If an IRQ is not assigned and a userspace
> driver tries to read()/write(), the generic uio
> framework will just return -EIO.
> 
> This allows binding uio_pci_generic to devices which
> cannot get an IRQ assigned, such as an NVMe controller
> behind Intel Volume Management Device (VMD), since VMD
> does not support INTx interrupts.
> 
> Signed-off-by: Jim Harris <james.r.harris@intel.com>

Without interrupts, why do you want uio? All it does is
forward interrupts to userspace.

> ---
>  drivers/uio/uio_pci_generic.c | 20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c
> index d0b508b68f3c..81c59b4f8552 100644
> --- a/drivers/uio/uio_pci_generic.c
> +++ b/drivers/uio/uio_pci_generic.c
> @@ -66,14 +66,7 @@ static int probe(struct pci_dev *pdev,
>  		return err;
>  	}
>  
> -	if (!pdev->irq) {
> -		dev_warn(&pdev->dev, "No IRQ assigned to device: "
> -			 "no support for interrupts?\n");
> -		pci_disable_device(pdev);
> -		return -ENODEV;
> -	}
> -
> -	if (!pci_intx_mask_supported(pdev)) {
> +	if (pci->irq && !pci_intx_mask_supported(pdev)) {
>  		err = -ENODEV;
>  		goto err_verify;
>  	}
> @@ -86,10 +79,15 @@ static int probe(struct pci_dev *pdev,
>  
>  	gdev->info.name = "uio_pci_generic";
>  	gdev->info.version = DRIVER_VERSION;
> -	gdev->info.irq = pdev->irq;
> -	gdev->info.irq_flags = IRQF_SHARED;
> -	gdev->info.handler = irqhandler;
>  	gdev->pdev = pdev;
> +	if (pdev->irq) {
> +		gdev->info.irq = pdev->irq;
> +		gdev->info.irq_flags = IRQF_SHARED;
> +		gdev->info.handler = irqhandler;
> +	} else {
> +		dev_warn(&pdev->dev, "No IRQ assigned to device: "
> +			 "no support for interrupts?\n");
> +	}
>  
>  	err = uio_register_device(&pdev->dev, &gdev->info);
>  	if (err)
> -- 
> 2.12.2