firewire: ohci: fix IR/IT context mask mixup
Stefan Richter [Sun, 21 Feb 2010 16:58:52 +0000 (17:58 +0100)]
This bug was present in firewire-ohci since day one:  The number of
available isochronous receive DMA contexts was mixed up with that of
available isochronous transmit DMA contexts.

This is harmless on a few chips which offer the same number of contexts
in both directions, but most chips nowadays implement only the standard
minimum of 4 IR contexts, but 8 IT contexts.  If a user attempted to run
a lot of IR contexts at once, results with more than four were therefore
unpredictable.  I suppose the controller would simply refuse to start
DMA of any unimplemented context.

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

drivers/firewire/ohci.c

index 9815137..a387bcd 100644 (file)
@@ -2395,17 +2395,17 @@ static int __devinit pci_probe(struct pci_dev *dev,
                     OHCI1394_AsRspTrContextControlSet, handle_at_packet);
 
        reg_write(ohci, OHCI1394_IsoRecvIntMaskSet, ~0);
-       ohci->it_context_mask = reg_read(ohci, OHCI1394_IsoRecvIntMaskSet);
+       ohci->ir_context_channels = ~0ULL;
+       ohci->ir_context_mask = reg_read(ohci, OHCI1394_IsoRecvIntMaskSet);
        reg_write(ohci, OHCI1394_IsoRecvIntMaskClear, ~0);
-       size = sizeof(struct iso_context) * hweight32(ohci->it_context_mask);
-       ohci->it_context_list = kzalloc(size, GFP_KERNEL);
+       size = sizeof(struct iso_context) * hweight32(ohci->ir_context_mask);
+       ohci->ir_context_list = kzalloc(size, GFP_KERNEL);
 
        reg_write(ohci, OHCI1394_IsoXmitIntMaskSet, ~0);
-       ohci->ir_context_channels = ~0ULL;
-       ohci->ir_context_mask = reg_read(ohci, OHCI1394_IsoXmitIntMaskSet);
+       ohci->it_context_mask = reg_read(ohci, OHCI1394_IsoXmitIntMaskSet);
        reg_write(ohci, OHCI1394_IsoXmitIntMaskClear, ~0);
-       size = sizeof(struct iso_context) * hweight32(ohci->ir_context_mask);
-       ohci->ir_context_list = kzalloc(size, GFP_KERNEL);
+       size = sizeof(struct iso_context) * hweight32(ohci->it_context_mask);
+       ohci->it_context_list = kzalloc(size, GFP_KERNEL);
 
        if (ohci->it_context_list == NULL || ohci->ir_context_list == NULL) {
                err = -ENOMEM;