linux-kernel - [PATCH AUTOSEL 4.18 067/131] media: em28xx: explicitly disable TS packet filter

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Message-ID: <20180902064601.183036-67-alexander.levin@microsoft.com>
Date:   Sun, 2 Sep 2018 13:04:25 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Robert Schlabbach <Robert.Schlabbach@....net>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 067/131] media: em28xx: explicitly disable TS
 packet filter

From: Robert Schlabbach <Robert.Schlabbach@....net>

[ Upstream commit 157eb9a0b75e97ad390c6e50c7381b0a0e02fe97 ]

The em28xx driver never touched the EM2874 register bits that control
the transport stream packet filters, leaving them at whatever default
the firmware has set. E.g. the Pinnacle 290e disables them by default,
while the Hauppauge WinTV dualHD enables discarding NULL packets by
default.

However, some applications require NULL packets, e.g. to determine the
load in DOCSIS segments, so discarding NULL packets is undesired for
such applications.

This patch simply extends the bit mask when starting or stopping the
transport stream packet capture, so that the filter bits are cleared.
It has been verified that this makes the Hauppauge WinTV dualHD pass
an unfiltered DVB-C stream including NULL packets, which it didn't
before.

Signed-off-by: Robert Schlabbach <Robert.Schlabbach@....net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/media/usb/em28xx/em28xx-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
index f70845e7d8c6..45b24776a695 100644
--- a/drivers/media/usb/em28xx/em28xx-core.c
+++ b/drivers/media/usb/em28xx/em28xx-core.c
@@ -655,12 +655,12 @@ int em28xx_capture_start(struct em28xx *dev, int start)
 			rc = em28xx_write_reg_bits(dev,
 						   EM2874_R5F_TS_ENABLE,
 						   start ? EM2874_TS1_CAPTURE_ENABLE : 0x00,
-						   EM2874_TS1_CAPTURE_ENABLE);
+						   EM2874_TS1_CAPTURE_ENABLE | EM2874_TS1_FILTER_ENABLE | EM2874_TS1_NULL_DISCARD);
 		else
 			rc = em28xx_write_reg_bits(dev,
 						   EM2874_R5F_TS_ENABLE,
 						   start ? EM2874_TS2_CAPTURE_ENABLE : 0x00,
-						   EM2874_TS2_CAPTURE_ENABLE);
+						   EM2874_TS2_CAPTURE_ENABLE | EM2874_TS2_FILTER_ENABLE | EM2874_TS2_NULL_DISCARD);
 	} else {
 		/* FIXME: which is the best order? */
 		/* video registers are sampled by VREF */
-- 
2.17.1