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

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Message-ID: <1511469909.4370.14.camel@Centos6.3-64>
Date:   Fri, 24 Nov 2017 04:45:09 +0800
From:   Ching Huang <ching2048@...ca.com.tw>
To:     Dan Carpenter <dan.carpenter@...cle.com>
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

Hello Dan,

On Thu, 2017-11-23 at 13:44 +0300, Dan Carpenter wrote:
> 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
S_IRUGO value is 00444, defined in <linux/stat.h> -> <uapi/linux/stat.h>.
     A. It will be not a issue.
> 
> > +MODULE_PARM_DESC(msi_enable, " Enable MSI interrupt(0 ~ 1), msi_enable=1(enable), =0(disable)");
>                                  ^
> Remove the extra space
OK
> 
> > +
> >  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.
update as below
---
		unsigned int irq_flag;
		irq_flag = PCI_IRQ_LEGACY;
		if (msi_enable == 1)
			irq_flag |= PCI_IRQ_MSI;
		nvec = pci_alloc_irq_vectors(pdev, 1, 1, irq_flag);
> >  
> > +		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.
update as below
---
		if (msi_enable == 1)
			dev_info(&pdev->dev, "msi enabled\n");

> 
> regards,
> dan carpenter
>