linux-kernel - [PATCH 3.16 032/306] [media] mb86a20s: fix the locking logic

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Message-ID: <lsq.1487198500.246962901@decadent.org.uk>
Date:   Wed, 15 Feb 2017 22:41:40 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Mauro Carvalho Chehab" <mchehab@....samsung.com>,
        "Mauro Carvalho Chehab" <mchehab@...pensource.com>
Subject: [PATCH 3.16 032/306] [media] mb86a20s: fix the locking logic

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit dafb65fb98d85d8e78405e82c83e81975e5d5480 upstream.

On this frontend, it takes a while to start output normal
TS data. That only happens on state S9. On S8, the TS output
is enabled, but it is not reliable enough.

However, the zigzag loop is too fast to let it sync.

As, on practical tests, the zigzag software loop doesn't
seem to be helping, but just slowing down the tuning, let's
switch to hardware algorithm, as the tuners used on such
devices are capable of work with frequency drifts without
any help from software.

Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/dvb-frontends/mb86a20s.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

--- a/drivers/media/dvb-frontends/mb86a20s.c
+++ b/drivers/media/dvb-frontends/mb86a20s.c
@@ -321,7 +321,11 @@ static int mb86a20s_read_status(struct d
 	if (val >= 7)
 		*status |= FE_HAS_SYNC;
 
-	if (val >= 8)				/* Maybe 9? */
+	/*
+	 * Actually, on state S8, it starts receiving TS, but the TS
+	 * output is only on normal state after the transition to S9.
+	 */
+	if (val >= 9)
 		*status |= FE_HAS_LOCK;
 
 	dev_dbg(&state->i2c->dev, "%s: Status = 0x%02x (state = %d)\n",
@@ -2080,6 +2084,11 @@ static void mb86a20s_release(struct dvb_
 	kfree(state);
 }
 
+static int mb86a20s_get_frontend_algo(struct dvb_frontend *fe)
+{
+        return DVBFE_ALGO_HW;
+}
+
 static struct dvb_frontend_ops mb86a20s_ops;
 
 struct dvb_frontend *mb86a20s_attach(const struct mb86a20s_config *config,
@@ -2153,6 +2162,7 @@ static struct dvb_frontend_ops mb86a20s_
 	.read_status = mb86a20s_read_status_and_stats,
 	.read_signal_strength = mb86a20s_read_signal_strength_from_cache,
 	.tune = mb86a20s_tune,
+	.get_frontend_algo = mb86a20s_get_frontend_algo,
 };
 
 MODULE_DESCRIPTION("DVB Frontend module for Fujitsu mb86A20s hardware");