[PATCH] powerpc/85xx: workaround for chips with MSI hareware errata to support MSI-X

[Jia Hongtao-B38951]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Tuesday, July 17, 2012 7:20 AM
> To: Jia Hongtao-B38951
> Cc: linuxppc-dev at lists.ozlabs.org; galak at kernel.crashing.org;
> soniccat.liu at gmail.com
> Subject: Re: [PATCH] powerpc/85xx: workaround for chips with MSI hareware
> errata to support MSI-X
> 
> On 07/15/2012 10:35 PM, Jia Hongtao wrote:
> > From: Liu Shuo <soniccat.liu at gmail.com>
> >
> > The MPIC chip with version 2.0 has a MSI errata (errata PIC1 of
> mpc8544),
> > It causes that neither MSI nor MSI-X can work fine. There is a
> workaround
> > to allow MSI-X to function properly.
> 
> s/There is/This is/
> 
> There is also a workaround for regular MSI to function properly, though
> this patch does not implement it.

You are right, this patch only to make MSI-X work. For now we have no plan
to make MSI work too.

> 
> > +/* MPIC chip with 2.0 version has erratum PIC1 */
> > +static int mpic_has_errata(struct platform_device *dev)
> > +{
> > +	struct device_node *mpic_node;
> > +
> > +	mpic_node = of_irq_find_parent(dev->dev.of_node);
> > +	if (mpic_node) {
> > +		u32 *reg_base, brr1 = 0;
> > +		/* Get the PIC reg base */
> > +		reg_base = of_iomap(mpic_node, 0);
> > +		of_node_put(mpic_node);
> > +		if (!reg_base) {
> > +			dev_err(&dev->dev, "ioremap problem failed.\n");
> > +			return -EIO;
> > +		}
> > +
> > +		/* Get the mpic chip version from block revision register 1
> */
> > +		brr1 = in_be32(reg_base + MPIC_FSL_BRR1);
> > +		iounmap(reg_base);
> > +		if ((brr1 & MPIC_FSL_BRR1_VER) == 0x0200)
> > +			return 1;
> 
> There's already been a patch posted that includes BRR1 checking:
> http://patchwork.ozlabs.org/patch/169713/
> 
> Please coordinate with that.  Have the MPIC code read the version once,
> and expose it to the MSI driver, rather than digging directly into the
> non-MSI MPIC registers from here.

Ok, I rebased the patch against kumar_next branch and the patch you mentioned
has not applied yet. Anyway I will fix this.


> 
> > diff --git a/arch/powerpc/sysdev/fsl_msi.h
> b/arch/powerpc/sysdev/fsl_msi.h
> > index 8225f86..354d546 100644
> > --- a/arch/powerpc/sysdev/fsl_msi.h
> > +++ b/arch/powerpc/sysdev/fsl_msi.h
> > @@ -25,6 +25,9 @@
> >  #define FSL_PIC_IP_IPIC   0x00000002
> >  #define FSL_PIC_IP_VMPIC  0x00000003
> >
> > +#define MSI_HW_ERRATA_MASK   0x000000F0
> > +#define MSI_HW_ERRATA_ENDIAN 0x00000010
> 
> Why do we need a mask for this?
> 

I don't know yet but I will find out.
This patch was from Liu Shuo so I need to do more investigation.

-Jia Hongtao.