V4L/DVB (4785): Budget-ci: Change DEBIADDR_IR to a safer default

The IR chip has no address decoding, so the IR data is always present in
the high byte when doing a read from the saa7146 chip. This means that
the DEBI address used is irrelevant to the IR decoding logic.
DEBI addresses 0x1XXX are mapped to the registers on the CI module
itself, but only the lowest two bits are actually used (see EN50221,
section A.2.2.1), meaning that 0x1234 is equivalent to 0x1000 which maps
to register 0 (the data register). A read from the data register is
supposed to be preceded by a read from the size register, so some CI
modules will be confused (the AlphaCrypt CAM will hang completely).
The attached patch changes the address used when reading the IR data to
use 0x4000 instead. This is the CI version address, which is a safer
default, works with the AlphaCrypt CAM and matches the behaviour of the
Windows driver (AFAIK).

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

diff --git a/drivers/media/dvb/ttpci/budget-ci.c b/drivers/media/dvb/ttpci/budget-ci.c
index 2a2e9b400613ed6674c8ee69c349ec64f484be79..ac0cecb14dc30be72b9d41c25541a227a2400903 100644 (file)
--- a/drivers/media/dvb/ttpci/budget-ci.c
+++ b/drivers/media/dvb/ttpci/budget-ci.c
@@ -46,7 +46,14 @@
 #include "bsbe1.h"
 #include "bsru6.h"
 
-#define DEBIADDR_IR            0x1234
+/*
+ * Regarding DEBIADDR_IR:
+ * Some CI modules hang if random addresses are read.
+ * Using address 0x4000 for the IR read means that we
+ * use the same address as for CI version, which should
+ * be a safe default.
+ */
+#define DEBIADDR_IR            0x4000
 #define DEBIADDR_CICONTROL     0x0000
 #define DEBIADDR_CIVERSION     0x4000
 #define DEBIADDR_IO            0x1000