V4L/DVB: stv090x: Add some notes about the internal tuner I/O control
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/stv090x.c b/drivers/media/dvb/frontends/stv090x.c
index a461fdf..425e7a4 100644
--- a/drivers/media/dvb/frontends/stv090x.c
+++ b/drivers/media/dvb/frontends/stv090x.c
@@ -758,6 +758,15 @@
{
u32 reg;
+ /*
+ * NOTE! A lock is used as a FSM to control the state in which
+ * access is serialized between two tuners on the same demod.
+ * This has nothing to do with a lock to protect a critical section
+ * which may in some other cases be confused with protecting I/O
+ * access to the demodulator gate.
+ * In case of any error, the lock is unlocked and exit within the
+ * relevant operations themselves.
+ */
if (enable)
mutex_lock(&state->internal->tuner_lock);