linux-kernel - Re: [PATCH 1/3] scsi: arcmsr: Add driver module parameter msi

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Message-ID: <20171123104408.jkslvj2axy4svt4a@mwanda>
Date:   Thu, 23 Nov 2017 13:44:09 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Ching Huang <ching2048@...ca.com.tw>
Cc:     martin.petersen@...cle.com, James.Bottomley@...senPartnership.com,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        jthumshirn@...e.de, hare@...e.de, hch@...radead.org
Subject: Re: [PATCH 1/3] scsi: arcmsr: Add driver module parameter msi_enable

On Thu, Nov 23, 2017 at 09:27:19AM +0800, Ching Huang wrote:
> From: Ching Huang <ching2048@...ca.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 <ching2048@...ca.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