firewire: fix use of multiple AV/C devices, allow multiple FCP listeners

Control of more than one AV/C device at once --- e.g. camcorders, tape
decks, audio devices, TV tuners --- failed or worked only unreliably,
depending on driver implementation.  This affected kernelspace and
userspace drivers alike and was caused by firewire-core's inability to
accept multiple registrations of FCP listeners.

The fix allows multiple address handlers to be registered for the FCP
command and response registers.  When a request for these registers is
received, all handlers are invoked, and the Firewire response is
generated by the core and not by any handler.

The cdev API does not change, i.e., userspace is still expected to send
a response for FCP requests; this response is silently ignored.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (changelog, rebased, whitespace)

1 files changed, 2 insertions, 10 deletions

diff --git a/drivers/media/dvb/firewire/firedtv-fw.c b/drivers/media/dvb/firewire/firedtv-fw.c
index fe44789ab037..6223bf01efe9 100644
--- a/drivers/media/dvb/firewire/firedtv-fw.c
+++ b/drivers/media/dvb/firewire/firedtv-fw.c
@@ -202,14 +202,8 @@ static void handle_fcp(struct fw_card *card, struct fw_request *request,
         unsigned long flags;
         int su;
 
-        if ((tcode != TCODE_WRITE_QUADLET_REQUEST &&
-             tcode != TCODE_WRITE_BLOCK_REQUEST) ||
-            offset != CSR_REGISTER_BASE + CSR_FCP_RESPONSE ||
-            length == 0 ||
-            (((u8 *)payload)[0] & 0xf0) != 0) {
-                fw_send_response(card, request, RCODE_TYPE_ERROR);
+        if (length < 2 || (((u8 *)payload)[0] & 0xf0) != 0)
                 return;
-        }
 
         su = ((u8 *)payload)[1] & 0x7;
 
@@ -230,10 +224,8 @@ static void handle_fcp(struct fw_card *card, struct fw_request *request,
         }
         spin_unlock_irqrestore(&node_list_lock, flags);
 
-        if (fdtv) {
+        if (fdtv)
                 avc_recv(fdtv, payload, length);
-                fw_send_response(card, request, RCODE_COMPLETE);
-        }
 }
 
 static struct fw_address_handler fcp_handler = {