Hi,

This patch, against 3.3-rc4, is basically a conglomerate of patches that
together seem to make CA support on mantis working and stable, even on SMP
systems. (I'm using a Terratec Cinergy DVB-S2 card with a Conax CAM, with
mumudvb as userspace.) There are a few fixes from this mailing list and some
of my own; the end result is too ugly to include, and there are still things
I don't understand at all, but I hope it can be useful for some.

Below is the list of what the patch does:

 - I've followed the instructions from some post on this mailing list
   to enable CAM support in the first place (mantis_set_direction move
   to mantis_pci.c, uncomment mantis_ca_init).

 - The MANTIS_GPIF_STATUS fix from http://patchwork.linuxtv.org/patch/8776/.
   Not that it seems to change a lot for me, but it makes sense.

 - I've fixed a ton of SMP-related bugs. Basically a lot of the members of
   mantis_ca were accessed from several threads without a mutex, which is a
   big no-no; I've mostly changed to using atomic operations here, although
   I also added some locks were it made sense (e.g. when resetting the CAM).
   The ca_lock is replaced by a more general int_stat_lock, which ideally
   is held when banging on MANTIS_INT_STAT. (I have no hardware
   documentation, so I'm afraid I don't really know the specifics here.)

 - mantis_hif_write_wait() would never clear MANTIS_SBUF_OPDONE_BIT,
   leading to a lot of operations never actually waiting for the callback.
   I've added many such fixes, as well as debugging output when the
   bit is in a surprising state (e.g., MANTIS_SBUF_OPDONE_BIT set before the
   beginning of an operation, where it really should be cleared).

 - Some operations check for timeout by testing if wait_event_timeout()
   return -ERESTARTSYS. However, wait_event_timeout() can can never
   do this; the return value for timeout is zero. I've fixed this
   (well, I seemingly forgot one; have to do that in the next version :-) ).
   Unfortunately, this make the problems in the next point a _lot_ worse,
   since timeouts are now actually percolated up the stack.

 - 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 the previous behavior
   except with a shorter timeout.

 - A hack to fix a mutex issue in the DVB layer; dvb_usercopy(), which is
   called on all ioctls, not only copies data to and from userspace,
   but also takes a lock on the file descriptor, which means that only one ioctl 
   can run at a time. This means that if one thread of mumudvb is busy trying
   to get, say, the SNR from the frontend (which can hang due to the issue
   above), the CAM thread's ioctl(fd, CA_GET_SLOT_INFO, ...) will hang,
   even though it doesn't need to communicate with the hardware at all.
   This obviously requires a better fix, but I don't know the generic DVB
   layer well enough to say what it is. Maybe it's some sort of remnant
   of from when all ioctl()s took the BKL. Note that on UMP kernels without
   preemption, mutex_lock is to the best of my knowledge a no-op, so these
   delay issues would not show up on non-SMP.

 - Tiny cleanups: Removed some unused mmread()s and structure members.
   Some debugging messages have been made more specific or clearer
   (e.g. reads say what address they're from, the I2C subsystem reports
   if there were any timeouts, the interrupt handler properly clears
   the RISC status word so it isn't shown as <Unknown>).

I'm still not happy with the bit-banging on the I2C interface (as opposed to
dealing with it in the interrupt handler); I long suspected it for causing
the IRQ0 problems, especially as they seem to have a sort-of similar issue
with I2CDONE/I2CRACk never being set, but it seem the DMA transfers is really
what causes it somehow, so I've left it alone.

Anyway, if there are specific pieces people want me to split out for
mainline, I'd be happy to do that and add the required Signed-Off-By lines
etc. Let me know.

/* Steinar */
-- 
Homepage: http://www.sesse.net/