Subject: Re: [PATCH] powerpc/fsl: Add multiple MSI bank support

From: Michael Ellerman <[email-masked]>
Date: Fri, 19 Mar 2010 14:06:54 +1100

On Thu, 2010-03-18 at 09:53 -0500, Kumar Gala wrote:
> From: Lan Chunhe-B25806 <[email-masked]>
> 
> Freescale QorIQ P4080 has three MSI banks and the original code
> can not work well. This patch adds multiple MSI banks support for
> Freescale processor.
> 
> Signed-off-by: Lan Chunhe-B25806 <[email-masked]>
> Signed-off-by: Roy Zang <[email-masked]>

> @@ -146,9 +149,13 @@ static int fsl_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)
>  	unsigned int virq;
>  	struct msi_desc *entry;
>  	struct msi_msg msg;
> -	struct fsl_msi *msi_data = fsl_msi;
> +	struct fsl_msi *msi_data;
>  
>  	list_for_each_entry(entry, &pdev->msi_list, list) {
> +		if (entry->irq == NO_IRQ)
> +			continue;

This looks wrong, entry->irq should always be 0 here because it was just
kzalloc'ed - you should only be doing this check in teardown.

> -	WARN_ON(ppc_md.setup_msi_irqs);
> -	ppc_md.setup_msi_irqs = fsl_setup_msi_irqs;
> -	ppc_md.teardown_msi_irqs = fsl_teardown_msi_irqs;
> -	ppc_md.msi_check_device = fsl_msi_check_device;
> +	/* The multiple setting ppc_md.setup_msi_irqs will not harm things */
> +	if (!ppc_md.setup_msi_irqs) {
> +		ppc_md.setup_msi_irqs = fsl_setup_msi_irqs;
> +		ppc_md.teardown_msi_irqs = fsl_teardown_msi_irqs;
> +		ppc_md.msi_check_device = fsl_msi_check_device;
> +	} else if (ppc_md.setup_msi_irqs != fsl_setup_msi_irqs) {
> +		dev_err(&dev->dev, "Different MSI driver already installed!\n");
> +		err = -EBUSY; /* or some other error code */
> +		goto error_out;
> +	}

I liked it the way it was, because having two competing MSI backends
means something's probably not going to work. But it's your driver so
whatever you like.

cheers