firewire: ohci: fix up configuration of TI chips

On TI chips (OHCI-Lynx and later), enable link enhancements features
that TI recommends to be used.  None of these are required for proper
operation, but they are safe and nice to have.

In theory, these bits should have been set by default, but in practice,
some BIOS/EEPROM writers apparently do not read the datasheet, or get
spooked by names like "unfair".

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index e934713..6a27a0e 100644 (file)
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2431,7 +2431,7 @@ 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;
+       u32 bus_options, max_receive, link_speed, version, link_enh;
        u64 guid;
        int i, err, n_ir, n_it;
        size_t size;
@@ -2484,6 +2484,23 @@ 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);
 

diff --git a/drivers/firewire/ohci.h b/drivers/firewire/ohci.h
index d49e146..3bc9a5d 100644 (file)
--- a/drivers/firewire/ohci.h
+++ b/drivers/firewire/ohci.h
@@ -154,4 +154,12 @@
 
 #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 */