From Newsgroup: comp.sys.raspberry-pi

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB adapter, but a power off reset finds it.

Anyone got half a clue as to why?
--
"The most difficult subjects can be explained to the most slow witted
man if he has not formed any idea of them already; but the simplest
thing cannot be made clear to the most intelligent man if he is firmly persuaded that he knows already, without a shadow of doubt, what is laid before him."

- Leo Tolstoy

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From Newsgroup: comp.sys.raspberry-pi

The Natural Philosopher wrote:

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB >adapter, but a power off reset finds it.

I had similar behaviour with a network card some while ago. Apparently
the reboot leaves the device in a state which makes it impossible for
the OS to detect it after the reboot. This actually is a bug in the
driver for the adapter, which you could report to the maintainer. When
you switch if off completely, "something" is set to standard values,
thus making the DVB adapter again available for the OS.

-jw-
--
And now for something completely different...
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From Newsgroup: comp.sys.raspberry-pi

On 11/06/2025 17:53, Joerg Walther wrote:

The Natural Philosopher wrote:

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB
adapter, but a power off reset finds it.

I had similar behaviour with a network card some while ago. Apparently
the reboot leaves the device in a state which makes it impossible for
the OS to detect it after the reboot. This actually is a bug in the
driver for the adapter, which you could report to the maintainer. When
you switch if off completely, "something" is set to standard values,
thus making the DVB adapter again available for the OS.

Mmm. Yes. Recognising the device is down at kernelish level...

IICBA (If i can be arsed) I'll file a report...
...its probably a single line of code. A power off reset will put the
device in a known state and a reboot needs to find it there and its
probably a question of writing sonmething to it that puts it there...as
a firstt attempt to find it

-jw-

--
Climate is what you expect but weather is what you get.
Mark Twain

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From Newsgroup: comp.sys.raspberry-pi

Joerg Walther <joerg.walther@magenta.de> writes:

The Natural Philosopher wrote:

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB >>adapter, but a power off reset finds it.

I had similar behaviour with a network card some while ago. Apparently
the reboot leaves the device in a state which makes it impossible for
the OS to detect it after the reboot. This actually is a bug in the
driver for the adapter, which you could report to the maintainer. When
you switch if off completely, "something" is set to standard values,
thus making the DVB adapter again available for the OS.

That sounds more like a bug in the device? i.e. not honoring the
reset signal from the host after reboot.
--
https://www.greenend.org.uk/rjk/
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From Newsgroup: comp.sys.raspberry-pi

On 12/06/2025 09:01, Richard Kettlewell wrote:

Joerg Walther <joerg.walther@magenta.de> writes:

The Natural Philosopher wrote:

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB
adapter, but a power off reset finds it.

I had similar behaviour with a network card some while ago. Apparently
the reboot leaves the device in a state which makes it impossible for
the OS to detect it after the reboot. This actually is a bug in the
driver for the adapter, which you could report to the maintainer. When
you switch if off completely, "something" is set to standard values,
thus making the DVB adapter again available for the OS.

That sounds more like a bug in the device? i.e. not honoring the
reset signal from the host after reboot.

Well hardware and software always blame each other :-)

In the end though, its the software's job to sort it out.

Wouldn't be the first time I've seen software engaging in some complex shenanigans to overcome a hardware default.
A unix that wouldn't boot untril I phoned the company themselves in the
USA who listened patently while I read out the onscreen information.

"Ah., Its hung checking for the maths co processor"
"What maths co processor?"
"the one that should have a jumper saying if its not there"
"Are you sure, how do you know"
"I know because I wrote the boot script"

Windows booted perfectly on the unit. Irrespective of jumper setting.
--
“Puritanism: The haunting fear that someone, somewhere, may be happy.”

H.L. Mencken, A Mencken Chrestomathy

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From Newsgroup: comp.sys.raspberry-pi

In message <wwva56dfkww.fsf@LkoBDZeT.terraraq.uk>
Richard Kettlewell <invalid@invalid.invalid> wrote:

Joerg Walther <joerg.walther@magenta.de> writes:

The Natural Philosopher wrote:

Finally identified something I had been suspecting for some time.
Issuing a 'reboot' command results in tvheadend unable to find the DVB adapter, but a power off reset finds it.

I had similar behaviour with a network card some while ago. Apparently
the reboot leaves the device in a state which makes it impossible for the OS to detect it after the reboot. This actually is a bug in the driver
for the adapter, which you could report to the maintainer. When you
switch if off completely, "something" is set to standard values, thus making the DVB adapter again available for the OS.

That sounds more like a bug in the device? i.e. not honoring the reset
signal from the host after reboot.

Doesn't it suggest that the driver, when run from a reboot, assumes
that the device has had a hardware reset, which won't have happened
on a reboot without power cycle?

It's common for devices to have a method to software reset them, though
the results may not be identical to a hardware reset.

David
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From Newsgroup: comp.sys.raspberry-pi

On Wed, 11 Jun 2025 18:53:56 +0200, Joerg Walther wrote:

This actually is a bug in the driver for the adapter, which you could
report to the maintainer.

I would agree. On a reboot, the driver should be able to initialize the
device to the same condition it would be after a power cycle.

There may be some exceptions, I dunno: maybe avoid reloading large
firmware blobs, that kind of thing. But it would be good to have options
for overriding all of these. Treat them only as optimizations.
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