On Thu, Nov 23, 2017 at 09:27:19AM +0800, Ching Huang wrote:
> From: Ching Huang <ching2...@areca.com.tw>
> 
> Add module parameter msi_enable to has a chance to disable msi interrupt if 
> it does not work properly.
> 
> Signed-off-by: Ching Huang <ching2...@areca.com.tw>
> ---
> 
> diff -uprN a/drivers/scsi/arcmsr/arcmsr_hba.c 
> b/drivers/scsi/arcmsr/arcmsr_hba.c
> --- a/drivers/scsi/arcmsr/arcmsr_hba.c        2017-11-23 14:29:26.000000000 
> +0800
> +++ b/drivers/scsi/arcmsr/arcmsr_hba.c        2017-11-23 16:02:28.000000000 
> +0800
> @@ -75,6 +75,10 @@ MODULE_DESCRIPTION("Areca ARC11xx/12xx/1
>  MODULE_LICENSE("Dual BSD/GPL");
>  MODULE_VERSION(ARCMSR_DRIVER_VERSION);
>  
> +static int msi_enable = 1;
> +module_param(msi_enable, int, S_IRUGO);
                                 ^^^^^^^
checkpatch.pl will complain that this should be 0444

> +MODULE_PARM_DESC(msi_enable, " Enable MSI interrupt(0 ~ 1), 
> msi_enable=1(enable), =0(disable)");
                                 ^
Remove the extra space

> +
>  static int host_can_queue = ARCMSR_DEFAULT_OUTSTANDING_CMD;
>  module_param(host_can_queue, int, S_IRUGO);
>  MODULE_PARM_DESC(host_can_queue, " adapter queue depth(32 ~ 1024), default 
> is 128");
> @@ -831,11 +835,15 @@ arcmsr_request_irq(struct pci_dev *pdev,
>               pr_info("arcmsr%d: msi-x enabled\n", acb->host->host_no);
>               flags = 0;
>       } else {
> -             nvec = pci_alloc_irq_vectors(pdev, 1, 1,
> -                             PCI_IRQ_MSI | PCI_IRQ_LEGACY);
> +             if (msi_enable == 1)
> +                     nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> +             else
> +                     nvec = pci_alloc_irq_vectors(pdev, 1, 1, 
> PCI_IRQ_LEGACY);
>               if (nvec < 1)
>                       return FAILED;

I feel like we should try PCI_IRQ_MSI then if it fails we could fall
back to PCI_IRQ_LEGACY.  Originally, it worked like this and now it just
fails unless you toggle the module param.  It's a regression.

>  
> +             if (msi_enable == 1)
> +                     pr_info("arcmsr%d: msi enabled\n", acb->host->host_no);

This printk could be improved.  Use dev_info(&pdev->dev, for a start.
I know that the other prints don't use this, but we could use it one
time then slowly add more users until more are using dev_info() than
pr_info() and then someone will decide to clean up the old users.

regards,
dan carpenter

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