Message ID | 1333401917-27203-4-git-send-email-gennarone@gmail.com (mailing list archive) |
---|---|
State | Rejected, archived |
Headers |
Received: from mail.tu-berlin.de ([130.149.7.33]) by www.linuxtv.org with esmtp (Exim 4.72) (envelope-from <linux-media-owner@vger.kernel.org>) id 1SEoly-0007Cn-Os for patchwork@linuxtv.org; Mon, 02 Apr 2012 23:26:46 +0200 X-tubIT-Incoming-IP: 209.132.180.67 Received: from vger.kernel.org ([209.132.180.67]) by mail.tu-berlin.de (exim-4.75/mailfrontend-2) with esmtp for <patchwork@linuxtv.org> id 1SEoly-00054N-GV; Mon, 02 Apr 2012 23:26:46 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370Ab2DBV0n (ORCPT <rfc822;patchwork@linuxtv.org>); Mon, 2 Apr 2012 17:26:43 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:58244 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751686Ab2DBV0m (ORCPT <rfc822; linux-media@vger.kernel.org>); Mon, 2 Apr 2012 17:26:42 -0400 Received: by mail-wg0-f44.google.com with SMTP id dr13so3083820wgb.1 for <linux-media@vger.kernel.org>; Mon, 02 Apr 2012 14:26:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; bh=5LCuGpg6sgVHf1TbzjrpGgCxK12Mc0xiI25+WO8DXpY=; b=IHtEVJm9p2+zNYb7nxqN85pa2CflKPplJcLq3JqRu7sq+10owATBtEMM55roJfvWKz +hG2cts3jelKO295eQ/Wm4NRN9S+uvyYPCqdu3SCp2o6jAEAQIW63TDLTl4w8jFcS4US OmEfX1nBKhQjAcC5yCwvNZIjpusbhb1gDQCUu1bklHQeUQv12SLjTeodfce4x0M6sD7k taNh/VxcaP2KwXRLe7qSSza7wYiTLmo2+O1Fm3p5FF5mq3TNvcCiD3whyYryKikHjrsY NcxaByTGmcHB0CCPdLdfxFAIvYcMW+rU9hADwS/lQzcKyVtVd+6pp2+/iY9A3kEANQUE 8LUA== Received: by 10.180.97.4 with SMTP id dw4mr29216369wib.18.1333402001426; Mon, 02 Apr 2012 14:26:41 -0700 (PDT) Received: from localhost.localdomain (93-50-34-119.ip150.fastwebnet.it. [93.50.34.119]) by mx.google.com with ESMTPS id 17sm46472981wis.0.2012.04.02.14.26.39 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 02 Apr 2012 14:26:40 -0700 (PDT) From: Gianluca Gennari <gennarone@gmail.com> To: linux-media@vger.kernel.org, crope@iki.fi Cc: m@bues.ch, hfvogt@gmx.net, mchehab@redhat.com, Gianluca Gennari <gennarone@gmail.com> Subject: [PATCH 3/5] tda18218: fix IF frequency for 7MHz bandwidth channels Date: Mon, 2 Apr 2012 23:25:15 +0200 Message-Id: <1333401917-27203-4-git-send-email-gennarone@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1333401917-27203-1-git-send-email-gennarone@gmail.com> References: <1333401917-27203-1-git-send-email-gennarone@gmail.com> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: <linux-media.vger.kernel.org> X-Mailing-List: linux-media@vger.kernel.org X-PMX-Version: 5.6.1.2065439, Antispam-Engine: 2.7.2.376379, Antispam-Data: 2012.4.2.211519 X-PMX-Spam: Gauge=IIIIIIIII, Probability=9%, Report=' FORGED_FROM_GMAIL 0.1, MULTIPLE_RCPTS 0.1, HTML_00_01 0.05, HTML_00_10 0.05, BODYTEXTP_SIZE_3000_LESS 0, BODY_SIZE_1000_LESS 0, BODY_SIZE_2000_LESS 0, BODY_SIZE_5000_LESS 0, BODY_SIZE_7000_LESS 0, BODY_SIZE_900_999 0, __ANY_URI 0, __CP_URI_IN_BODY 0, __FRAUD_BODY_WEBMAIL 0, __FRAUD_WEBMAIL 0, __FRAUD_WEBMAIL_FROM 0, __FROM_GMAIL 0, __HAS_MSGID 0, __HAS_X_MAILER 0, __HAS_X_MAILING_LIST 0, __MIME_TEXT_ONLY 0, __MULTIPLE_RCPTS_CC_X2 0, __PHISH_SPEAR_STRUCTURE_1 0, __SANE_MSGID 0, __SUBJ_ALPHA_END 0, __TO_MALFORMED_2 0, __TO_NO_NAME 0, __URI_NO_WWW 0, __URI_NS ' |
Commit Message
Gianluca Gennari
April 2, 2012, 9:25 p.m. UTC
This is necessary to tune VHF channels with the AVerMedia A835 stick.
Signed-off-by: Gianluca Gennari <gennarone@gmail.com>
---
drivers/media/common/tuners/tda18218.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
Comments
On 03.04.2012 00:25, Gianluca Gennari wrote: > This is necessary to tune VHF channels with the AVerMedia A835 stick. > > Signed-off-by: Gianluca Gennari<gennarone@gmail.com> > --- > drivers/media/common/tuners/tda18218.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/media/common/tuners/tda18218.c b/drivers/media/common/tuners/tda18218.c > index dfb3a83..b079696 100644 > --- a/drivers/media/common/tuners/tda18218.c > +++ b/drivers/media/common/tuners/tda18218.c > @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend *fe) > priv->if_frequency = 3000000; > } else if (bw<= 7000000) { > LP_Fc = 1; > - priv->if_frequency = 3500000; > + priv->if_frequency = 4000000; > } else { > LP_Fc = 2; > priv->if_frequency = 4000000; Kwaak, I will not apply that until I have done background checking. That driver is used only by AF9015 currently. And I did that driver as reverse-engineering and thus there is some things guessed. I have only 8 MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T modulator either... Maybe some AF9015 user can confirm? Is there any AF9015 & TDA18218 bug reports seen in discussion forums... regards Antti
Il 03/04/2012 00:40, Antti Palosaari ha scritto: > On 03.04.2012 00:25, Gianluca Gennari wrote: >> This is necessary to tune VHF channels with the AVerMedia A835 stick. >> >> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >> --- >> drivers/media/common/tuners/tda18218.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/drivers/media/common/tuners/tda18218.c >> b/drivers/media/common/tuners/tda18218.c >> index dfb3a83..b079696 100644 >> --- a/drivers/media/common/tuners/tda18218.c >> +++ b/drivers/media/common/tuners/tda18218.c >> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >> *fe) >> priv->if_frequency = 3000000; >> } else if (bw<= 7000000) { >> LP_Fc = 1; >> - priv->if_frequency = 3500000; >> + priv->if_frequency = 4000000; >> } else { >> LP_Fc = 2; >> priv->if_frequency = 4000000; > > Kwaak, I will not apply that until I have done background checking. That > driver is used only by AF9015 currently. And I did that driver as > reverse-engineering and thus there is some things guessed. I have only 8 > MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T > modulator either... Maybe some AF9015 user can confirm? Is there any > AF9015 & TDA18218 bug reports seen in discussion forums... A friend has a AF9015+TDA18218 stick and told me that it works fine with the patch (including VHF), but to be safe I will ask him to double check with the current media_build tree, with and without the patch. In the worst case, we can add a new parameter (or an array of parameters) for the IF frequency to struct tda18218_config. Regards, Gianluca -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 04/03/2012 02:44 AM, Gianluca Gennari wrote: > Il 03/04/2012 00:40, Antti Palosaari ha scritto: >> On 03.04.2012 00:25, Gianluca Gennari wrote: >>> This is necessary to tune VHF channels with the AVerMedia A835 stick. >>> >>> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >>> --- >>> drivers/media/common/tuners/tda18218.c | 2 +- >>> 1 files changed, 1 insertions(+), 1 deletions(-) >>> >>> diff --git a/drivers/media/common/tuners/tda18218.c >>> b/drivers/media/common/tuners/tda18218.c >>> index dfb3a83..b079696 100644 >>> --- a/drivers/media/common/tuners/tda18218.c >>> +++ b/drivers/media/common/tuners/tda18218.c >>> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >>> *fe) >>> priv->if_frequency = 3000000; >>> } else if (bw<= 7000000) { >>> LP_Fc = 1; >>> - priv->if_frequency = 3500000; >>> + priv->if_frequency = 4000000; >>> } else { >>> LP_Fc = 2; >>> priv->if_frequency = 4000000; >> >> Kwaak, I will not apply that until I have done background checking. That >> driver is used only by AF9015 currently. And I did that driver as >> reverse-engineering and thus there is some things guessed. I have only 8 >> MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T >> modulator either... Maybe some AF9015 user can confirm? Is there any >> AF9015 & TDA18218 bug reports seen in discussion forums... > > A friend has a AF9015+TDA18218 stick and told me that it works fine with > the patch (including VHF), but to be safe I will ask him to double check > with the current media_build tree, with and without the patch. In the > worst case, we can add a new parameter (or an array of parameters) for > the IF frequency to struct tda18218_config. PASSED on 7MHz bw MUX - 'TerraTec Cinergy T Stick RC'. rgds, poma -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03.04.2012 03:44, Gianluca Gennari wrote: > Il 03/04/2012 00:40, Antti Palosaari ha scritto: >> On 03.04.2012 00:25, Gianluca Gennari wrote: >>> This is necessary to tune VHF channels with the AVerMedia A835 stick. >>> >>> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >>> --- >>> drivers/media/common/tuners/tda18218.c | 2 +- >>> 1 files changed, 1 insertions(+), 1 deletions(-) >>> >>> diff --git a/drivers/media/common/tuners/tda18218.c >>> b/drivers/media/common/tuners/tda18218.c >>> index dfb3a83..b079696 100644 >>> --- a/drivers/media/common/tuners/tda18218.c >>> +++ b/drivers/media/common/tuners/tda18218.c >>> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >>> *fe) >>> priv->if_frequency = 3000000; >>> } else if (bw<= 7000000) { >>> LP_Fc = 1; >>> - priv->if_frequency = 3500000; >>> + priv->if_frequency = 4000000; >>> } else { >>> LP_Fc = 2; >>> priv->if_frequency = 4000000; >> >> Kwaak, I will not apply that until I have done background checking. That >> driver is used only by AF9015 currently. And I did that driver as >> reverse-engineering and thus there is some things guessed. I have only 8 >> MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T >> modulator either... Maybe some AF9015 user can confirm? Is there any >> AF9015& TDA18218 bug reports seen in discussion forums... > > A friend has a AF9015+TDA18218 stick and told me that it works fine with > the patch (including VHF), but to be safe I will ask him to double check > with the current media_build tree, with and without the patch. In the > worst case, we can add a new parameter (or an array of parameters) for > the IF frequency to struct tda18218_config. Public short datasheet [1], page 16, says default IFs are BW=8 MHz IF=4 MHz, BW=7 MHz IF=3.5 MHz, BW=6 MHz IF=3 MHz. I suspect it still locks in some cases even IF is off-by 0.5 MHz for BW 7 and 8 but performance is reduced. So there is now something wrong, likely bug in the tda18218 driver. Could someone send me Windows sniff from success tune to 7 MHz BW channel? [1] http://www.nxp.com/documents/data_sheet/TDA18218HN.pdf
Il 03/04/2012 12:19, Antti Palosaari ha scritto: > On 03.04.2012 03:44, Gianluca Gennari wrote: >> Il 03/04/2012 00:40, Antti Palosaari ha scritto: >>> On 03.04.2012 00:25, Gianluca Gennari wrote: >>>> This is necessary to tune VHF channels with the AVerMedia A835 stick. >>>> >>>> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >>>> --- >>>> drivers/media/common/tuners/tda18218.c | 2 +- >>>> 1 files changed, 1 insertions(+), 1 deletions(-) >>>> >>>> diff --git a/drivers/media/common/tuners/tda18218.c >>>> b/drivers/media/common/tuners/tda18218.c >>>> index dfb3a83..b079696 100644 >>>> --- a/drivers/media/common/tuners/tda18218.c >>>> +++ b/drivers/media/common/tuners/tda18218.c >>>> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >>>> *fe) >>>> priv->if_frequency = 3000000; >>>> } else if (bw<= 7000000) { >>>> LP_Fc = 1; >>>> - priv->if_frequency = 3500000; >>>> + priv->if_frequency = 4000000; >>>> } else { >>>> LP_Fc = 2; >>>> priv->if_frequency = 4000000; >>> >>> Kwaak, I will not apply that until I have done background checking. That >>> driver is used only by AF9015 currently. And I did that driver as >>> reverse-engineering and thus there is some things guessed. I have only 8 >>> MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T >>> modulator either... Maybe some AF9015 user can confirm? Is there any >>> AF9015& TDA18218 bug reports seen in discussion forums... >> >> A friend has a AF9015+TDA18218 stick and told me that it works fine with >> the patch (including VHF), but to be safe I will ask him to double check >> with the current media_build tree, with and without the patch. In the >> worst case, we can add a new parameter (or an array of parameters) for >> the IF frequency to struct tda18218_config. > > Public short datasheet [1], page 16, says default IFs are BW=8 MHz IF=4 > MHz, BW=7 MHz IF=3.5 MHz, BW=6 MHz IF=3 MHz. I suspect it still locks in > some cases even IF is off-by 0.5 MHz for BW 7 and 8 but performance is > reduced. So there is now something wrong, likely bug in the tda18218 > driver. > > Could someone send me Windows sniff from success tune to 7 MHz BW channel? > > [1] http://www.nxp.com/documents/data_sheet/TDA18218HN.pdf Hi Antti, the situation is a bit confusing. The A835 always needed the IF frequency modification to tune VHF channels, even with the famous Xgazza patch based on your old af9035 driver. Instead, the af9015 was working fine in VHF band with the default 3.5MHz IF frequency, until the recent rewrite of the tda18218 driver (which I believe happened around kernel 3.0). After that, the af9015 started working also with the 4MHz IF frequency (it's not clear if it still works also with 3.5MHz, I will ask my friend to check this). So probably you are right, there could be a bug in the tda18218 tuner that was introduced recently. A discussion on the A835 and VHF can be found on the Italian Ubuntu forum (in Italian of course): http://forum.ubuntu-it.org/index.php/topic,384436.msg3700932.html#msg3700932 Do you have any suggestion on the tool to sniff the windows driver? Some time ago I tried SnoopyPro 0.22 and I was able to capture the first ~6000 packets of the A835 initialization, then it stopped capturing before the first picture was displayed. Do you think it's enough? Do you know any better free tool? Regards, Gianluca -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Il 03/04/2012 12:19, Antti Palosaari ha scritto: > On 03.04.2012 03:44, Gianluca Gennari wrote: >> Il 03/04/2012 00:40, Antti Palosaari ha scritto: >>> On 03.04.2012 00:25, Gianluca Gennari wrote: >>>> This is necessary to tune VHF channels with the AVerMedia A835 stick. >>>> >>>> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >>>> --- >>>> drivers/media/common/tuners/tda18218.c | 2 +- >>>> 1 files changed, 1 insertions(+), 1 deletions(-) >>>> >>>> diff --git a/drivers/media/common/tuners/tda18218.c >>>> b/drivers/media/common/tuners/tda18218.c >>>> index dfb3a83..b079696 100644 >>>> --- a/drivers/media/common/tuners/tda18218.c >>>> +++ b/drivers/media/common/tuners/tda18218.c >>>> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >>>> *fe) >>>> priv->if_frequency = 3000000; >>>> } else if (bw<= 7000000) { >>>> LP_Fc = 1; >>>> - priv->if_frequency = 3500000; >>>> + priv->if_frequency = 4000000; >>>> } else { >>>> LP_Fc = 2; >>>> priv->if_frequency = 4000000; >>> >>> Kwaak, I will not apply that until I have done background checking. That >>> driver is used only by AF9015 currently. And I did that driver as >>> reverse-engineering and thus there is some things guessed. I have only 8 >>> MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T >>> modulator either... Maybe some AF9015 user can confirm? Is there any >>> AF9015& TDA18218 bug reports seen in discussion forums... >> >> A friend has a AF9015+TDA18218 stick and told me that it works fine with >> the patch (including VHF), but to be safe I will ask him to double check >> with the current media_build tree, with and without the patch. In the >> worst case, we can add a new parameter (or an array of parameters) for >> the IF frequency to struct tda18218_config. > > Public short datasheet [1], page 16, says default IFs are BW=8 MHz IF=4 > MHz, BW=7 MHz IF=3.5 MHz, BW=6 MHz IF=3 MHz. I suspect it still locks in > some cases even IF is off-by 0.5 MHz for BW 7 and 8 but performance is > reduced. So there is now something wrong, likely bug in the tda18218 > driver. > > Could someone send me Windows sniff from success tune to 7 MHz BW channel? > > [1] http://www.nxp.com/documents/data_sheet/TDA18218HN.pdf Hi Antti, I did some testing with the A835 and the findings are interesting. With the old tda18218 driver the af9015 sticks required IF=3.5MHz to tune VHF channels, while the A835 required IF=4MHz. With the current driver, both the af9015 and the A835 are much more tolerant to IF frequency variations. In particular, the A835 is capable to successfully tune UHF channels with IF in the range [3.5,5.5] MHz, and VHF channels with IF in the range [3.0,6.5] MHz, inclusive. I don't know if this may be considered the symptom of a bug, but for sure the patch I posted is useless with the current driver. If you are still interested in a USB sniff of the Windows driver, just let me know. Best regards, Gianluca -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 04.04.2012 16:15, Gianluca Gennari wrote: > Il 03/04/2012 12:19, Antti Palosaari ha scritto: >> On 03.04.2012 03:44, Gianluca Gennari wrote: >>> Il 03/04/2012 00:40, Antti Palosaari ha scritto: >>>> On 03.04.2012 00:25, Gianluca Gennari wrote: >>>>> This is necessary to tune VHF channels with the AVerMedia A835 stick. >>>>> >>>>> Signed-off-by: Gianluca Gennari<gennarone@gmail.com> >>>>> --- >>>>> drivers/media/common/tuners/tda18218.c | 2 +- >>>>> 1 files changed, 1 insertions(+), 1 deletions(-) >>>>> >>>>> diff --git a/drivers/media/common/tuners/tda18218.c >>>>> b/drivers/media/common/tuners/tda18218.c >>>>> index dfb3a83..b079696 100644 >>>>> --- a/drivers/media/common/tuners/tda18218.c >>>>> +++ b/drivers/media/common/tuners/tda18218.c >>>>> @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend >>>>> *fe) >>>>> priv->if_frequency = 3000000; >>>>> } else if (bw<= 7000000) { >>>>> LP_Fc = 1; >>>>> - priv->if_frequency = 3500000; >>>>> + priv->if_frequency = 4000000; >>>>> } else { >>>>> LP_Fc = 2; >>>>> priv->if_frequency = 4000000; >>>> >>>> Kwaak, I will not apply that until I have done background checking. That >>>> driver is used only by AF9015 currently. And I did that driver as >>>> reverse-engineering and thus there is some things guessed. I have only 8 >>>> MHz wide signal, thus I never tested 7 and 6 MHz. Have no DVB-T >>>> modulator either... Maybe some AF9015 user can confirm? Is there any >>>> AF9015& TDA18218 bug reports seen in discussion forums... >>> >>> A friend has a AF9015+TDA18218 stick and told me that it works fine with >>> the patch (including VHF), but to be safe I will ask him to double check >>> with the current media_build tree, with and without the patch. In the >>> worst case, we can add a new parameter (or an array of parameters) for >>> the IF frequency to struct tda18218_config. >> >> Public short datasheet [1], page 16, says default IFs are BW=8 MHz IF=4 >> MHz, BW=7 MHz IF=3.5 MHz, BW=6 MHz IF=3 MHz. I suspect it still locks in >> some cases even IF is off-by 0.5 MHz for BW 7 and 8 but performance is >> reduced. So there is now something wrong, likely bug in the tda18218 >> driver. >> >> Could someone send me Windows sniff from success tune to 7 MHz BW channel? >> >> [1] http://www.nxp.com/documents/data_sheet/TDA18218HN.pdf > > Hi Antti, > I did some testing with the A835 and the findings are interesting. With > the old tda18218 driver the af9015 sticks required IF=3.5MHz to tune VHF > channels, while the A835 required IF=4MHz. > > With the current driver, both the af9015 and the A835 are much more > tolerant to IF frequency variations. > In particular, the A835 is capable to successfully tune UHF channels > with IF in the range [3.5,5.5] MHz, and VHF channels with IF in the > range [3.0,6.5] MHz, inclusive. IF frequency is frequency used between tuner and demodulator. Thus it should be same for the tuner, it is sender Tx, and for demodulator which receives it. As you can guess it is like radio channel, it will work if it is a little bit wrong but performance will be reduced. IF frequency is generally more tuner characteristic than demodulator. I mean it is likely tuner decides which is optimal IF for signal tuner is transferring to demod. Earlier we used configuration option for both tuner and demod to set IF. But as the fact is tuner must know it always we added new tuner callback .get_if_frequency() demodulator can ask used IF from the tuner. Recently I converted AF9013 driver to use that .get_if_frequency(). I think at that point I may have introduced some bug. And one point to mention, it is sometimes used a little bit different IFs that are tuner defaults. It is somehow device design specific, for maximum performance device engineers will ran some test to find out optimal IF which gives best performance. One reason could be example there is RF noise peak (RF spurs) just in used IF which reduces performance => lets shift default IF a little bit for maximum performance. > I don't know if this may be considered the symptom of a bug, but for > sure the patch I posted is useless with the current driver. > If you are still interested in a USB sniff of the Windows driver, just > let me know. I have used old SniffUSB2.0 http://www.pcausa.com/Utilities/UsbSnoop/ Works fine with Windows XP. Sniff is welcome. regards Antti
Il 04/04/2012 15:27, Antti Palosaari ha scritto: > IF frequency is frequency used between tuner and demodulator. Thus it > should be same for the tuner, it is sender Tx, and for demodulator which > receives it. As you can guess it is like radio channel, it will work if > it is a little bit wrong but performance will be reduced. > > IF frequency is generally more tuner characteristic than demodulator. I > mean it is likely tuner decides which is optimal IF for signal tuner is > transferring to demod. Earlier we used configuration option for both > tuner and demod to set IF. But as the fact is tuner must know it always > we added new tuner callback .get_if_frequency() demodulator can ask used > IF from the tuner. > > Recently I converted AF9013 driver to use that .get_if_frequency(). I > think at that point I may have introduced some bug. > > And one point to mention, it is sometimes used a little bit different > IFs that are tuner defaults. It is somehow device design specific, for > maximum performance device engineers will ran some test to find out > optimal IF which gives best performance. One reason could be example > there is RF noise peak (RF spurs) just in used IF which reduces > performance => lets shift default IF a little bit for maximum performance. I found out the origin of the problem: in the old "hacked" driver the demodulator IF frequency was erroneously hard-coded to 4.57 MHz (like with the mxl5007t tuner) so there was a mismatch between the tuner and the demodulator IF setting. In UHF band, the difference was only 0.57 MHz, so it still worked (probably with reduced performance). Instead, in VHF band the difference was over 1 MHz so it was not working. Hacking the tuner IF frequency to 4 MHz in VHF band was enough to get it working, but of course it was not optimal. In the end, there is no bug in the current code. Sorry for all the unnecessary noise about this issue. Regards, Gianluca -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/media/common/tuners/tda18218.c b/drivers/media/common/tuners/tda18218.c index dfb3a83..b079696 100644 --- a/drivers/media/common/tuners/tda18218.c +++ b/drivers/media/common/tuners/tda18218.c @@ -144,7 +144,7 @@ static int tda18218_set_params(struct dvb_frontend *fe) priv->if_frequency = 3000000; } else if (bw <= 7000000) { LP_Fc = 1; - priv->if_frequency = 3500000; + priv->if_frequency = 4000000; } else { LP_Fc = 2; priv->if_frequency = 4000000;