[PATCH 4/6] media: drxk: stop accessing a disconnected device

[Josef Schlehofer <pepe.schlehofer@gmail.com>]

drxk continues frontend status polling after its USB device disappears.
read_status() keeps issuing I2C accesses, and drxk_get_stats() ignores
the error from get_lock_status(), so callers see "no signal".

Enter DRXK_NO_DEV when an I2C transfer returns -ENODEV and reject
further hardware accesses in that state. Propagate -ENODEV from
drxk_get_stats() so read_status() reports the disconnect.

Also check the state after the tuner's gate control in
drxk_set_parameters() before continuing demodulator setup.

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
---
 drivers/media/dvb-frontends/drxk_hard.c | 29 ++++++++++++++++++++++---
 drivers/media/dvb-frontends/drxk_hard.h |  2 +-
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/media/dvb-frontends/drxk_hard.c b/drivers/media/dvb-frontends/drxk_hard.c
index 0815083e54eb..df5f5ea959ce 100644
--- a/drivers/media/dvb-frontends/drxk_hard.c
+++ b/drivers/media/dvb-frontends/drxk_hard.c
@@ -208,10 +208,27 @@ static void drxk_i2c_unlock(struct drxk_state *state)
 static int drxk_i2c_transfer(struct drxk_state *state, struct i2c_msg *msgs,
 			     unsigned len)
 {
+	int status;
+
+	/* Don't touch the bus once the device is known to be gone */
+	if (state->m_drxk_state == DRXK_NO_DEV)
+		return -ENODEV;
+
 	if (state->drxk_i2c_exclusive_lock)
-		return __i2c_transfer(state->i2c, msgs, len);
+		status = __i2c_transfer(state->i2c, msgs, len);
 	else
-		return i2c_transfer(state->i2c, msgs, len);
+		status = i2c_transfer(state->i2c, msgs, len);
+
+	/*
+	 * -ENODEV from the I2C adapter means that the device is gone for
+	 * good, e.g. an unplugged USB bridge. Stop accessing it from now on.
+	 */
+	if (status == -ENODEV) {
+		state->m_drxk_state = DRXK_NO_DEV;
+		pr_warn("device is gone, stopping all I2C access\n");
+	}
+
+	return status;
 }
 
 static int i2c_read1(struct drxk_state *state, u8 adr, u8 *val)
@@ -6319,6 +6336,10 @@ static int drxk_set_parameters(struct dvb_frontend *fe)
 	if (fe->ops.i2c_gate_ctrl)
 		fe->ops.i2c_gate_ctrl(fe, 0);
 
+	/* The device may have disappeared while the tuner was programmed */
+	if (state->m_drxk_state == DRXK_NO_DEV)
+		return -ENODEV;
+
 	old_delsys = state->props.delivery_system;
 	state->props = *p;
 
@@ -6487,7 +6508,9 @@ static int drxk_get_stats(struct dvb_frontend *fe)
 
 	/* get status */
 	state->fe_status = 0;
-	get_lock_status(state, &stat);
+	status = get_lock_status(state, &stat);
+	if (status == -ENODEV)
+		return status;
 	if (stat == MPEG_LOCK)
 		state->fe_status |= 0x1f;
 	if (stat == FEC_LOCK)
diff --git a/drivers/media/dvb-frontends/drxk_hard.h b/drivers/media/dvb-frontends/drxk_hard.h
index a850a876deee..dc6ee0bb6854 100644
--- a/drivers/media/dvb-frontends/drxk_hard.h
+++ b/drivers/media/dvb-frontends/drxk_hard.h
@@ -106,7 +106,7 @@ enum e_drxk_state {
 	DRXK_DTV_STARTED,
 	DRXK_ATV_STARTED,
 	DRXK_POWERED_DOWN,
-	DRXK_NO_DEV			/* If drxk init failed */
+	DRXK_NO_DEV			/* drxk init failed or device gone */
 };
 
 enum e_drxk_coef_array_index {
-- 
2.54.0 (Apple Git-157)