firewire: ohci: fix TI TSB82AA2 regression since 2.6.35

Revert commit 54672386cc
"firewire: ohci: fix up configuration of TI chips".
It caused massive slow-down and data corruption with a TSB82AA2 based
StarTech EC1394B2 ExpressCard and FireWire 800 harddisks.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/657081
http://thread.gmane.org/gmane.linux.kernel.firewire.user/4013

The fact that some card EEPROMs do not program these enhancements may be
related to TSB81BA3 phy chip errata, if not to bugs of TSB82AA2 itself.
We could re-add these configuration steps, but only conditional on a
whitelist of cards on which these enhancements bring a proven positive
effect.

Reported-and-tested-by: Eric Shattow <lucent@gmail.com>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org> 2.6.35
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/ohci.c

@@ -2840,7 +2840,7 @@ static int __devinit pci_probe(struct pci_dev *dev,
 			       const struct pci_device_id *ent)
 {
 	struct fw_ohci *ohci;
-	u32 bus_options, max_receive, link_speed, version, link_enh;
+	u32 bus_options, max_receive, link_speed, version;
 	u64 guid;
 	int i, err, n_ir, n_it;
 	size_t size;
@@ -2894,23 +2894,6 @@ static int __devinit pci_probe(struct pci_dev *dev,
 	if (param_quirks)
 		ohci->quirks = param_quirks;
 
-	/* TI OHCI-Lynx and compatible: set recommended configuration bits. */
-	if (dev->vendor == PCI_VENDOR_ID_TI) {
-		pci_read_config_dword(dev, PCI_CFG_TI_LinkEnh, &link_enh);
-
-		/* adjust latency of ATx FIFO: use 1.7 KB threshold */
-		link_enh &= ~TI_LinkEnh_atx_thresh_mask;
-		link_enh |= TI_LinkEnh_atx_thresh_1_7K;
-
-		/* use priority arbitration for asynchronous responses */
-		link_enh |= TI_LinkEnh_enab_unfair;
-
-		/* required for aPhyEnhanceEnable to work */
-		link_enh |= TI_LinkEnh_enab_accel;
-
-		pci_write_config_dword(dev, PCI_CFG_TI_LinkEnh, link_enh);
-	}
-
 	ar_context_init(&ohci->ar_request_ctx, ohci,
 			OHCI1394_AsReqRcvContextControlSet);
 

drivers/firewire/ohci.h

@@ -155,12 +155,4 @@
 
 #define OHCI1394_phy_tcode		0xe
 
-/* TI extensions */
-
-#define PCI_CFG_TI_LinkEnh		0xf4
-#define  TI_LinkEnh_enab_accel		0x00000002
-#define  TI_LinkEnh_enab_unfair		0x00000080
-#define  TI_LinkEnh_atx_thresh_mask	0x00003000
-#define  TI_LinkEnh_atx_thresh_1_7K	0x00001000
-
 #endif /* _FIREWIRE_OHCI_H */