linux-kernel - Re: [PATCH 2/3] media: si2157: add support for 1.7MHz and 6.1 MHz

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 6 Jan 2022 16:39:39 +0100
From:   Robert Schlabbach <Robert.Schlabbach@....net>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     mauro.chehab@...wei.com, Antti Palosaari <crope@....fi>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 2/3] media: si2157: add support for 1.7MHz and 6.1 MHz

Sorry for the late test and response, but there is a BAD BUG in this patch:

+ if (SUPPORTS_1700KHz(dev) && c->bandwidth_hz <= 1700000)
+ bandwidth = 0x09;
if (c->bandwidth_hz <= 6000000)
bandwidth = 0x06;
+ if (SUPPORTS_1700KHz(dev) && c->bandwidth_hz <= 6100000)
+ bandwidth = 0x10;
else if (c->bandwidth_hz <= 7000000)
bandwidth = 0x07;
else if (c->bandwidth_hz <= 8000000)

The additions omitted the "else", which resulted in the bandwidth setting for
6MHz being overwritten with the one for 6.1MHz - and that completely breaks
6MHz channels, as the tuner then refuses to accept the tune command!

As a result, e.g. MCNS aka ClearQAM aka DVB-C Annex B no longer works after
this patch.

I don't know if the 1.7Mhz and 6.1MHz settings are even usable, if the tuner
(in my case, the Si2157-A30) then no longer accepts the tune command. Maybe
they're not suited for frequency-based tuning, but only for channel-based
tuning? That would not fit the DVB-API, I think.

And the 1.7MHz bandwidth setting currently can't do any harm, as it is always
overwritten by the 6MHz bandwidth setting, also due to an "else" missing.

Best Regards,
-Robert Schlabbach

Gesendet: Freitag, 10. Dezember 2021 um 13:59 Uhr
Von: "Mauro Carvalho Chehab" <mchehab+huawei@...nel.org>
An: unlisted-recipients:;
Cc: linuxarm@...wei.com, mauro.chehab@...wei.com, "Mauro Carvalho Chehab" <mchehab+huawei@...nel.org>, "Antti Palosaari" <crope@....fi>, "Mauro Carvalho Chehab" <mchehab@...nel.org>, linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Betreff: [PATCH 2/3] media: si2157: add support for 1.7MHz and 6.1 MHz
Some tuners allow setting the bandwidth filter to 1.7MHz and
6.1 MHz. Add support for it upstream, as the narrower is the
bandwidth filter, the better.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
---

To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH 0/3] at: https://lore.kernel.org/all/cover.1639140967.git.mchehab+huawei@kernel.org/

drivers/media/tuners/si2157.c | 4 ++++
drivers/media/tuners/si2157_priv.h | 5 +++++
2 files changed, 9 insertions(+)

diff --git a/drivers/media/tuners/si2157.c b/drivers/media/tuners/si2157.c
index aeecb38b147f..2d3937af4f5f 100644
--- a/drivers/media/tuners/si2157.c
+++ b/drivers/media/tuners/si2157.c
@@ -458,8 +458,12 @@ static int si2157_set_params(struct dvb_frontend *fe)
goto err;
}

+ if (SUPPORTS_1700KHz(dev) && c->bandwidth_hz <= 1700000)
+ bandwidth = 0x09;
if (c->bandwidth_hz <= 6000000)
bandwidth = 0x06;
+ if (SUPPORTS_1700KHz(dev) && c->bandwidth_hz <= 6100000)
+ bandwidth = 0x10;
else if (c->bandwidth_hz <= 7000000)
bandwidth = 0x07;
else if (c->bandwidth_hz <= 8000000)
diff --git a/drivers/media/tuners/si2157_priv.h b/drivers/media/tuners/si2157_priv.h
index df17a5f03561..24849c8ed398 100644
--- a/drivers/media/tuners/si2157_priv.h
+++ b/drivers/media/tuners/si2157_priv.h
@@ -66,6 +66,11 @@ struct si2157_cmd {
unsigned rlen;
};

+#define SUPPORTS_1700KHz(dev) (((dev)->part_id == SI2141) || \
+ ((dev)->part_id == SI2147) || \
+ ((dev)->part_id == SI2157) || \
+ ((dev)->part_id == SI2177))
+
/* Old firmware namespace */
#define SI2158_A20_FIRMWARE "dvb-tuner-si2158-a20-01.fw"
#define SI2141_A10_FIRMWARE "dvb-tuner-si2141-a10-01.fw"
--
2.33.1