[patch] workaround zd1201 interference problem

[patch] workaround zd1201 interference problem

[Pavel Machek]

zd1201 likes to start up shouting, interfering with all wifis in
range. It is capable of stopping ipw2200 up-to few meters away, and
stops other cards at smaller distances, too.

This works around it. Only forcing ZD1201_CMDCODE_DISABLE is not
enough to prevent interference.

From: Jirka Benc <jbenc@suse.cz>
Signed-off-by: Pavel Machek <pavel@suse.cz>


--- linux-good/drivers/net/wireless/zd1201.c	2006-03-30 13:51:58.000000000 +0200
+++ linux/drivers/net/wireless/zd1201.c	2006-06-07 15:55:01.000000000 +0200
@@ -1835,6 +1835,8 @@
 	    zd->dev->name);
 	
 	usb_set_intfdata(interface, zd);
+	zd1201_enable(zd);	/* zd1201 likes to startup shouting, interfering */
+	zd1201_disable(zd); 	/* with all the wifis in range */
 	return 0;
 
 err_net:

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[Jiri Benc]

On Wed, 7 Jun 2006 16:00:45 +0200, Pavel Machek wrote:
> +	zd1201_enable(zd);	/* zd1201 likes to startup shouting, interfering */
> +	zd1201_disable(zd); 	/* with all the wifis in range */

I would prefer to track it down and find out where exactly is the
problem instead of this quick hack.

 Jiri

-- 
Jiri Benc
SUSE Labs

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

On St 07-06-06 16:08:28, Jiri Benc wrote:
> On Wed, 7 Jun 2006 16:00:45 +0200, Pavel Machek wrote:
> > +	zd1201_enable(zd);	/* zd1201 likes to startup shouting, interfering */
> > +	zd1201_disable(zd); 	/* with all the wifis in range */
> 
> I would prefer to track it down and find out where exactly is the
> problem instead of this quick hack.

Well, I'll try _enable() alone, but it seems to me that _enable()
command is needed to initialize radio properly. I do not think we can
get much further without firmware sources...

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[Daniel Drake]

Pavel Machek wrote:
> Well, I'll try _enable() alone, but it seems to me that _enable()
> command is needed to initialize radio properly. I do not think we can
> get much further without firmware sources...

If you can formulate a proper and technical description of the issue 
(and exactly what is needed to workaround it), I can contact ZyDAS for 
you. They have been very helpful with ZD1211.

Daniel

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

Hi!

> >Well, I'll try _enable() alone, but it seems to me that _enable()
> >command is needed to initialize radio properly. I do not think we can
> >get much further without firmware sources...
> 
> If you can formulate a proper and technical description of the issue 
> (and exactly what is needed to workaround it), I can contact ZyDAS for 
> you. They have been very helpful with ZD1211.

Okay, the issue is:

if you plug zd1201 into USB, it starts jamming radio,
immediately. Enable/disable, or iwlist wlan0 scan, or basically any
operation unjams the radio. This patch works it around:

diff --git a/drivers/net/wireless/zd1201.c b/drivers/net/wireless/zd1201.c
index 335eaf3..dcc7bc7 100644
--- a/drivers/net/wireless/zd1201.c
+++ b/drivers/net/wireless/zd1201.c
@@ -1835,8 +1835,8 @@ static int zd1201_probe(struct usb_inter
 	    zd->dev->name);
 	
 	usb_set_intfdata(interface, zd);
-	zd1201_enable(zd);
-	zd1201_disable(zd);
+	zd1201_enable(zd);	/* zd1201 likes to startup enabled, interfering */
+	zd1201_disable(zd); 	/* with all the wifis in range */
 	return 0;
 
 err_net:


....question is "is that right solution, or is something different
needed to solve that problem properly"?
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

Hi!

> > >Well, I'll try _enable() alone, but it seems to me that _enable()
> > >command is needed to initialize radio properly. I do not think we can
> > >get much further without firmware sources...
> > 
> > If you can formulate a proper and technical description of the issue 
> > (and exactly what is needed to workaround it), I can contact ZyDAS for 
> > you. They have been very helpful with ZD1211.
> 
> Okay, the issue is:
> 
> if you plug zd1201 into USB, it starts jamming radio,
> immediately. Enable/disable, or iwlist wlan0 scan, or basically any
> operation unjams the radio. This patch works it around:

Of course, the patch should have been:

 diff --git a/drivers/net/wireless/zd1201.c b/drivers/net/wireless/zd1201.c
 index 335eaf3..dcc7bc7 100644
 --- a/drivers/net/wireless/zd1201.c
 +++ b/drivers/net/wireless/zd1201.c
 @@ -1835,6 +1835,8 @@ static int zd1201_probe(struct usb_inter
  	    zd->dev->name);
  	
  	usb_set_intfdata(interface, zd);
 +	zd1201_enable(zd);	/* zd1201 likes to startup enabled, interfering */
 +	zd1201_disable(zd); 	/* with all the wifis in range */
  	return 0;
  
  err_net:
 
 
 ....question is "is that right solution, or is something different
 needed to solve that problem properly"?
 								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[Daniel Drake]

Pavel Machek wrote:
> if you plug zd1201 into USB, it starts jamming radio,
> immediately. Enable/disable, or iwlist wlan0 scan, or basically any
> operation unjams the radio. This patch works it around:

Can we be any more specific?

What is the interference - is it transmitting random packets, or just 
emitting a magical cloud of invisible anti-wifi?

At which precise point does the interference start? Does it happen even 
without the driver loaded?

Which operation is the one which stops the interference, the enable or 
the disable?

Does this happen on every plug in, or just sometimes? Is it affected by 
usage patterns such as having the device plugged in throughout boot, 
reloading the module, etc?

Thanks,
Daniel

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

Hi!

I'll try to.

> >if you plug zd1201 into USB, it starts jamming radio,
> >immediately. Enable/disable, or iwlist wlan0 scan, or basically any
> >operation unjams the radio. This patch works it around:
> 
> Can we be any more specific?
> 
> What is the interference - is it transmitting random packets, or just 
> emitting a magical cloud of invisible anti-wifi?

Magical cloud, I'm afraid.

> At which precise point does the interference start? 

When the card is inserted.

> Does it happen even 
> without the driver loaded?

Will try.

> Which operation is the one which stops the interference, the enable or 
> the disable?

Disable alone was not enough to stop interference.

> Does this happen on every plug in, or just sometimes? 

In 70% or so.

> Is it affected by 
> usage patterns such as having the device plugged in throughout boot, 
> reloading the module, etc?

Will try.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[John W. Linville]

On Sat, Jun 10, 2006 at 12:38:04AM +0200, Pavel Machek wrote:

> > Which operation is the one which stops the interference, the enable or 
> > the disable?
> 
> Disable alone was not enough to stop interference.

I'm going to drop this patch for now, in the hopes that with Daniel's
ZyDas contacts you can devise a more palatable solution.

Thanks,

John
-- 
John W. Linville
linville@tuxdriver.com

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

Hi!

> > > Which operation is the one which stops the interference, the enable or 
> > > the disable?
> > 
> > Disable alone was not enough to stop interference.
> 
> I'm going to drop this patch for now, in the hopes that with Daniel's
> ZyDas contacts you can devise a more palatable solution.

I'd actually like you to keep it, it does not seem ZyDas contacts are
going anywhere.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[Pavel Machek]

Hi!

> Pavel Machek wrote:
> >if you plug zd1201 into USB, it starts jamming radio,
> >immediately. Enable/disable, or iwlist wlan0 scan, or basically any
> >operation unjams the radio. This patch works it around:
> 
> Can we be any more specific?
> 
> At which precise point does the interference start? Does it happen even 
> without the driver loaded?
> 
> Which operation is the one which stops the interference, the enable or 
> the disable?

enable alone is enough to stop the interference, but leaving card
enabled after load seems like a dirty hack.

> Does this happen on every plug in, or just sometimes? Is it affected by 
> usage patterns such as having the device plugged in throughout boot, 
> reloading the module, etc?

If I remove the firmware file, interference does not start... that
should be close to "not having module loaded".

I think I've answered all the questions now? :-).

								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [patch] workaround zd1201 interference problem

[John W. Linville]

----- Forwarded message from Pavel Machek <pavel@ucw.cz> -----

> zd1201 has nasty tendency to emit magicall anti-wifi cloud when it is
> inserted into slot, but not used.
> 
> Signed-off-by: Pavel Machek <pavel@suse.cz>
> 
> --- linux-good/drivers/usb/net/zd1201.c	2006-03-30 13:51:58.000000000 +0200
> +++ linux/drivers/net/wireless/zd1201.c	2006-06-15 23:28:04.000000000 +0200
> @@ -1835,6 +1835,8 @@
>  	    zd->dev->name);
>  	
>  	usb_set_intfdata(interface, zd);
> +	zd1201_enable(zd);	/* zd1201 likes to startup enabled, interfering */
> +	zd1201_disable(zd); 	/* with all the wifis in range */
>  	return 0;
>  
>  err_net:

Pavel's patch is still the best thing proposed so far to resolve this
issue, ugly as it may be.

It does seem to fix a real issue.  Is anyone gonna puke if a merge
this?  If so, where is your patch?

John
-- 
John W. Linville
linville@tuxdriver.com

Re: [patch] workaround zd1201 interference problem

[Daniel Drake]

Pavel Machek wrote:
> I'd actually like you to keep it, it does not seem ZyDas contacts are
> going anywhere.

ZyDAS did not respond to me about this. At least we know more about the 
problem now anyway :)

Daniel