linux-kernel - [PATCH 4.2.y-ckt 091/273] [media] tda1004x: only update the frontend properties if locked

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Message-Id: <1457391064-6660-92-git-send-email-kamal@canonical.com>
Date:	Mon,  7 Mar 2016 14:48:02 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 091/273] [media] tda1004x: only update the frontend properties if locked

4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Mauro Carvalho Chehab <mchehab@....samsung.com>

commit e8beb02343e7582980c6705816cd957cf4f74c7a upstream.

The tda1004x was updating the properties cache before locking.
If the device is not locked, the data at the registers are just
random values with no real meaning.

This caused the driver to fail with libdvbv5, as such library
calls GET_PROPERTY from time to time, in order to return the
DVB stats.

Tested with a saa7134 card 78:
	ASUSTeK P7131 Dual, vendor PCI ID: 1043:4862

Signed-off-by: Mauro Carvalho Chehab <mchehab@....samsung.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/media/dvb-frontends/tda1004x.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/dvb-frontends/tda1004x.c b/drivers/media/dvb-frontends/tda1004x.c
index 0e209b5..c6abeb4 100644
--- a/drivers/media/dvb-frontends/tda1004x.c
+++ b/drivers/media/dvb-frontends/tda1004x.c
@@ -903,9 +903,18 @@ static int tda1004x_get_fe(struct dvb_frontend *fe)
 {
 	struct dtv_frontend_properties *fe_params = &fe->dtv_property_cache;
 	struct tda1004x_state* state = fe->demodulator_priv;
+	int status;
 
 	dprintk("%s\n", __func__);
 
+	status = tda1004x_read_byte(state, TDA1004X_STATUS_CD);
+	if (status == -1)
+		return -EIO;
+
+	/* Only update the properties cache if device is locked */
+	if (!(status & 8))
+		return 0;
+
 	// inversion status
 	fe_params->inversion = INVERSION_OFF;
 	if (tda1004x_read_byte(state, TDA1004X_CONFC1) & 0x20)
-- 
2.7.0