linux-kernel - RE: [PATCH 1/7] powerpc: Add interface to get msi region information

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Date:	Wed, 9 Oct 2013 04:47:19 +0000
From:	Bhushan Bharat-R65777 <R65777@...escale.com>
To:	Wood Scott-B07421 <B07421@...escale.com>
CC:	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"joro@...tes.org" <joro@...tes.org>,
	"benh@...nel.crashing.org" <benh@...nel.crashing.org>,
	"galak@...nel.crashing.org" <galak@...nel.crashing.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"agraf@...e.de" <agraf@...e.de>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: RE: [PATCH 1/7] powerpc: Add interface to get msi region information



> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Wednesday, October 09, 2013 4:27 AM
> To: Bhushan Bharat-R65777
> Cc: alex.williamson@...hat.com; joro@...tes.org; benh@...nel.crashing.org;
> galak@...nel.crashing.org; linux-kernel@...r.kernel.org; linuxppc-
> dev@...ts.ozlabs.org; linux-pci@...r.kernel.org; agraf@...e.de;
> iommu@...ts.linux-foundation.org; Bhushan Bharat-R65777
> Subject: Re: [PATCH 1/7] powerpc: Add interface to get msi region information
> 
> On Thu, 2013-09-19 at 12:59 +0530, Bharat Bhushan wrote:
> > @@ -376,6 +405,7 @@ static int fsl_of_msi_probe(struct platform_device *dev)
> >  	int len;
> >  	u32 offset;
> >  	static const u32 all_avail[] = { 0, NR_MSI_IRQS };
> > +	static int bank_index;
> >
> >  	match = of_match_device(fsl_of_msi_ids, &dev->dev);
> >  	if (!match)
> > @@ -419,8 +449,8 @@ static int fsl_of_msi_probe(struct platform_device *dev)
> >  				dev->dev.of_node->full_name);
> >  			goto error_out;
> >  		}
> > -		msi->msiir_offset =
> > -			features->msiir_offset + (res.start & 0xfffff);
> > +		msi->msiir = res.start + features->msiir_offset;
> > +		printk("msi->msiir = %llx\n", msi->msiir);
> 
> dev_dbg or remove

Oops, sorry it was leftover of debugging :(

> 
> >  	}
> >
> >  	msi->feature = features->fsl_pic_ip; @@ -470,6 +500,7 @@ static int
> > fsl_of_msi_probe(struct platform_device *dev)
> >  		}
> >  	}
> >
> > +	msi->bank_index = bank_index++;
> 
> What if multiple MSIs are boing probed in parallel?

Ohh, I have not thought that it can be called in parallel

>  bank_index is not atomic.

Will declare bank_intex as atomic_t and use atomic_inc_return(&bank_index)

> 
> > diff --git a/arch/powerpc/sysdev/fsl_msi.h
> > b/arch/powerpc/sysdev/fsl_msi.h index 8225f86..6bd5cfc 100644
> > --- a/arch/powerpc/sysdev/fsl_msi.h
> > +++ b/arch/powerpc/sysdev/fsl_msi.h
> > @@ -29,12 +29,19 @@ struct fsl_msi {
> >  	struct irq_domain *irqhost;
> >
> >  	unsigned long cascade_irq;
> > -
> > -	u32 msiir_offset; /* Offset of MSIIR, relative to start of CCSR */
> > +	dma_addr_t msiir; /* MSIIR Address in CCSR */
> 
> Are you sure dma_addr_t is right here, versus phys_addr_t?  It implies that it's
> the output of the DMA API, but I don't think the DMA API is used in the MSI
> driver.  Perhaps it should be, but we still want the raw physical address to
> pass on to VFIO.

Looking through the conversation I will make this phys_addr_t

> 
> >  	void __iomem *msi_regs;
> >  	u32 feature;
> >  	int msi_virqs[NR_MSI_REG];
> >
> > +	/*
> > +	 * During probe each bank is assigned a index number.
> > +	 * index number ranges from 0 to 2^32.
> > +	 * Example  MSI bank 1 = 0
> > +	 * MSI bank 2 = 1, and so on.
> > +	 */
> > +	int bank_index;
> 
> 2^32 doesn't fit in "int" (nor does 2^32 - 1).

Right :(

> 
> Just say that indices start at 0.

Will correct this

Thanks
-Bharat

> 
> -Scott
>