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>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/media/dvb/frontends/stv090x.c b/drivers/media/dvb/frontends/stv090x.c
index a461fdff2c9c..425e7a43ae19 100644
--- a/drivers/media/dvb/frontends/stv090x.c
+++ b/drivers/media/dvb/frontends/stv090x.c
@@ -758,6 +758,15 @@ static int stv090x_i2c_gate_ctrl(struct stv090x_state *state, int enable)
 {
         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);