Subject: Re: [PATCH v2 2/4] gpu/radeon: Move 64-bit MSI quirk from arch to driver

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 03 Oct 2014 07:02:25 +1000

On Thu, 2014-10-02 at 09:34 -0600, Bjorn Helgaas wrote:
> On Thu, Oct 02, 2014 at 10:34:22AM +1000, Benjamin Herrenschmidt wrote:
> > 
> > A number of radeon cards have a HW limitation causing them to be
> > unable to generate the full 64-bit of address bits for MSIs. This
> > breaks MSIs on some platforms such as POWER machines.
> > 
> > We used to have a powerpc specific quirk to address that on a
> > single card, but this doesn't scale very well, this is better
> > put under control of the drivers who know precisely what a given
> > HW revision can do.
> > 
> > This moves the setting of the quirk flag to the radeon driver
> > 
> > Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
> > ---
> > 
> > v2: This is just adjusted to the new flag name
> 
> I'm sorta confused because I got two "v2 2/4" emails a minute or so apart.
> I assume they're the same.

Yes, evo blew up while sending the series the first time around :(
> > 
> >  arch/powerpc/kernel/pci_64.c            |  1 -
> >  drivers/gpu/drm/radeon/radeon_irq_kms.c | 10 ++++++++++
> >  2 files changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
> > index d41a831..5330f6d 100644
> > --- a/arch/powerpc/kernel/pci_64.c
> > +++ b/arch/powerpc/kernel/pci_64.c
> > @@ -271,5 +271,4 @@ static void quirk_radeon_32bit_msi(struct pci_dev *dev)
> >  {
> >  	dev->no_64bit_msi = true;
> >  }
> > -DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x68f2, quirk_radeon_32bit_msi);
> >  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0xaa68, quirk_radeon_32bit_msi);
> 
> Why do we keep the 0xaa68 quirk?  Shouldn't that be made generic, too?
> 
> > diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
> > index 16807af..e760671 100644
> > --- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
> > +++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
> > @@ -202,6 +202,16 @@ static bool radeon_msi_ok(struct radeon_device *rdev)
> >  	if (rdev->flags & RADEON_IS_AGP)
> >  		return false;
> >  
> > +	/*
> > +	 * Older chips have a HW limitation, they can only generate 40 bits
> > +	 * of address for "64-bit" MSIs which breaks on some platforms, notably
> > +	 * IBM POWER servers, so we limit them
> > +	 */
> > +	if (rdev->family < CHIP_BONAIRE) {
> > +		dev_info(rdev->dev, "radeon: MSI limited to 32-bit\n");
> > +		rdev->pdev->no_64bit_msi = true;
> > +	}
> > +
> >  	/* force MSI on */
> >  	if (radeon_msi == 1)
> >  		return true;
> > 
> > 
> >