From: "Steinar H. Gunderson" <sesse@xxxxxxxxxxxx>
As others have noticed, sometimes, especially during DMA transfers, the IRQ0
flag is never properly set and thus reads never return. (The typical case for
this is when we've just done a write and the en50221 thread is waiting for the
CAM status word to signal STATUSREG_DA; if this doesn't happen in a reasonable
amount of time, the upstream libdvben50221.so will report errors back to
mumudvb.)
I have no idea why this happens more often on SMP systems than on UMP systems,
but they really seem to do. I haven't found any reasonable workaround for
reliable polling either, so I'm making a hack -- if there's nothing returned in
two milliseconds, the read is simply assumed to have completed.
This is an unfortunate hack, but in practice it's identical to earlier
behavior except with a shorter timeout.
Signed-off-by: Steinar H. Gunderson <sesse@xxxxxxxxxxxx>
---
drivers/media/dvb/mantis/mantis_hif.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/media/dvb/mantis/mantis_hif.c b/drivers/media/dvb/mantis/mantis_hif.c
index a3ec2a2..0da3c6d 100644
--- a/drivers/media/dvb/mantis/mantis_hif.c
+++ b/drivers/media/dvb/mantis/mantis_hif.c
@@ -45,11 +45,19 @@ static int mantis_hif_sbuf_opdone_wait(struct mantis_ca *ca)
struct mantis_pci *mantis = ca->ca_priv;
int rc = 0;
+ /*
+ * HACK: Sometimes, especially during DMA transfers, and especially on
+ * SMP systems (!), the IRQ-0 flag is never set, or at least we don't get it
+ * (could it be that we're clearing it?). Thus, simply wait for 2 ms and then
+ * assume we got an answer even if we didn't. This works around lots of CA
+ * timeouts. The code with 500 ms wait and -EREMOTEIO is technically the
+ * correct one, though.
+ */
if (wait_event_timeout(ca->hif_opdone_wq,
test_and_clear_bit(MANTIS_SBUF_OPDONE_BIT, &ca->hif_event),
- msecs_to_jiffies(500)) == 0) {
+ msecs_to_jiffies(2)) == 0) {
- dprintk(MANTIS_ERROR, 1, "Adapter(%d) Slot(0): Smart buffer operation timeout !", mantis->num);
+ dprintk(MANTIS_ERROR, 1, "Adapter(%d) Slot(0): Smart buffer operation timeout ! (ignoring)", mantis->num);
rc = -EREMOTEIO;
}
dprintk(MANTIS_DEBUG, 1, "Smart Buffer Operation complete");
--
1.7.9.5
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