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firewire: ohci: wait for local CSR lock access to finish

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Add a loop to wait for the controller to finish a locally-initiated CSR
lock operation.  Google shows some occurrences of the "swap not done
yet" message which might indicate that some OHCI controllers are not
fast enough to do the lock/swap in the time needed for one PCI access.

This also correctly handles the case where the lock operation did not
finish, instead of silently returning an uninitialized value.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Clemens Ladisch 2010-04-12 10:35:44 +02:00 committed by Stefan Richter
parent 2608203daf
commit e1393667be
1 changed files with 13 additions and 7 deletions
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20
drivers/firewire/ohci.c
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@ -1158,7 +1158,7 @@ static void handle_local_lock(struct fw_ohci *ohci,
struct fw_packet *packet, u32 csr)
{
struct fw_packet response;
int tcode, length, ext_tcode, sel;
int tcode, length, ext_tcode, sel, try;
__be32 *payload, lock_old;
u32 lock_arg, lock_data;
@ -1185,13 +1185,19 @@ static void handle_local_lock(struct fw_ohci *ohci,
reg_write(ohci, OHCI1394_CSRCompareData, lock_arg);
reg_write(ohci, OHCI1394_CSRControl, sel);
if (reg_read(ohci, OHCI1394_CSRControl) & 0x80000000)
lock_old = cpu_to_be32(reg_read(ohci, OHCI1394_CSRData));
else
fw_notify("swap not done yet\n");
for (try = 0; try < 20; try++)
if (reg_read(ohci, OHCI1394_CSRControl) & 0x80000000) {
lock_old = cpu_to_be32(reg_read(ohci,
OHCI1394_CSRData));
fw_fill_response(&response, packet->header,
RCODE_COMPLETE, &lock_old, sizeof(lock_old));
RCODE_COMPLETE,
&lock_old, sizeof(lock_old));
goto out;
}
fw_error("swap not done (CSR lock timeout)\n");
fw_fill_response(&response, packet->header, RCODE_BUSY, NULL, 0);
out:
fw_core_handle_response(&ohci->card, &response);
}