• Rpi4B needs power off reboot for TV hat

    From The Natural Philosopher@21:1/5 to All on Tue Jun 10 10:05:51 2025
    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 Joerg Walther@21:1/5 to The Natural Philosopher on Wed Jun 11 18:53:56 2025
    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 The Natural Philosopher@21:1/5 to Joerg Walther on Wed Jun 11 22:27:59 2025
    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 Richard Kettlewell@21:1/5 to Joerg Walther on Thu Jun 12 09:01:35 2025
    Joerg Walther <[email protected]> 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 The Natural Philosopher@21:1/5 to Richard Kettlewell on Thu Jun 12 10:14:57 2025
    On 12/06/2025 09:01, Richard Kettlewell wrote:
    Joerg Walther <[email protected]> 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 David Higton@21:1/5 to Richard Kettlewell on Thu Jun 12 22:23:30 2025
    In message <[email protected]>
    Richard Kettlewell <[email protected]d> wrote:

    Joerg Walther <[email protected]> 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 Lawrence D'Oliveiro@21:1/5 to Joerg Walther on Sat Jun 14 02:52:53 2025
    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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