[PATCH] ssb: Clear RETRY_TIMEOUT in PCI Configuration

["Michael Büsch" <mb@bu3sch.de>]

On Wed, 2010-11-10 at 00:09 +0100, Rafa? Mi?ecki wrote: 
> 2010/10/19 Michael B?sch <mb@bu3sch.de>:
> > On Tue, 2010-10-19 at 12:55 -0500, Larry Finger wrote:
> >> MMIO log traces obtained using the Broadcom wl hybrid driver show that
> >> the RETRY_TIMEOUT register (0x41) in PCI configuration space is cleared
> >> if non-zero. Similar code found in other drivers such as ipw2100 show
> >> this operation is needed to keep PCI Tx retries from interfering with
> >> C3 CPU state. There are no known cases where omission of this code has
> >> caused a problem, but this patch is offered just in case such a situation
> >> occurs.
> >>
> >> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
> >> ---
> >>
> >> John,
> >>
> >> No particular urgency for this patch.
> >>
> >> Larry
> >> ---
> >>
> >> Index: wireless-testing/drivers/ssb/driver_pcicore.c
> >> ===================================================================
> >> --- wireless-testing.orig/drivers/ssb/driver_pcicore.c
> >> +++ wireless-testing/drivers/ssb/driver_pcicore.c
> >> @@ -271,6 +271,7 @@ int ssb_pcicore_plat_dev_init(struct pci
> >>  static void ssb_pcicore_fixup_pcibridge(struct pci_dev *dev)
> >>  {
> >>       u8 lat;
> >> +     u32 val;
> >>
> >>       if (dev->bus->ops != &ssb_pcicore_pciops) {
> >>               /* This is not a device on the PCI-core bridge. */
> >> @@ -288,6 +289,12 @@ static void ssb_pcicore_fixup_pcibridge(
> >>               return;
> >>       }
> >>
> >> +     /* Disable the RETRY_TIMEOUT register (0x41) to keep
> >> +      * PCI Tx retries from interfering with C3 CPU state */
> >> +     pci_read_config_dword(pci_dev, 0x40, &val);
> >> +     if ((val & 0x0000ff00) != 0)
> >> +             pci_write_config_dword(pci_dev, 0x40, val & 0xffff00ff);
> >> +
> >>       /* Enable PCI bridge BAR1 prefetch and burst */
> >>       pci_write_config_dword(dev, SSB_BAR1_CONTROL, 3);
> >
> >
> > Hm, do you realize that this function will only be executed for PCI
> > devices that live on top of a native SSB bus? Is that intentional?
> >
> > It won't affect normal broadcom wireless PCI devices.
> > It will only have an affect on a broadcom wireless PCI device that lives
> > behind a SSB->PCI bridge on an embedded device.
> 
> Is this patch needed? Shouldn't this be replaced by second version
> affecting "normal devices"?
> 
> I can see both applied to wireless-testing.

They certainly should _not_ be applied both.
John, some fixing is needed. Please remove this patch.

-- 
Greetings Michael.