1. Tim Akgayev's Avatar
    I recently bought a used note 4 frim ebay. It was listed that it had problems with resetting and freezing. Indeed it turned out the phone reboots frequently, brining me to a"Downloading... do not turn off target device" Along with that there is a debug console message that says mmc_read failure. Nevertheless after about a hundred tries I managed to reflash the thing (Odin kept failing to write the rom). Still the reboots persisted giving the same mmc errors persist. Sometimes the dubug would says mmc_write fail sometimes it would say mmc_read fail, sometimes both. I then ran into some topics sayin that it's definitely an inherent hardware issue that is pervasive on note 4s. The multimedia controller (mmc) chip seems to fail over time on these. Now this mmc chip manages the flash memory as far as I understand, so if it's failing then the whole 32 gb internal flash would soon become inoperable and I won't be able to boot at all. With all of that said I managed to fix the problem completely. I noticed that the phone only reboots when the screen is off, so I assumed it had something to do with the standby state that the cpu falls into after idling for a while. I simply aquire and hold a partial wakelock on the cpu (there's an app for that) and the phone works flawlessly, never once has it rebooted during this past week and I use the phone heavily everyday. The battery drains a little faster but that's a nonissue.

    Now that's all well and good however I do have some future concerns as to the failing chip. First of all I don't entire understand why the phone works so well even the the memory controller has trouble reading/writing. I save files all the time, download apps, transfer files from pc and never had an error saying that the file can't be written or read nor had I ever had an app crash. So I'm a little confused why that is.

    The second thing is that I'm still not sure I mitigated the issue completely. Will it eventually get worse? Will the phone stor age still degrade over time? If so how long approximately can the phone last in working order with such a condion. Thanks.
    flyingkytez likes this.
    09-03-2017 05:52 PM
  2. Paradroid01's Avatar
    10...9...8...7...6...
    09-04-2017 05:55 AM
  3. pr3jker's Avatar
    Emmc means memory hardware failure, this is the end for n4
    09-04-2017 03:11 PM
  4. Tim Akgayev's Avatar
    Emmc means memory hardware failure, this is the end for n4
    You didn't even read details I posted.
    09-05-2017 12:29 AM
  5. natehoy's Avatar
    It's very hard to say. I suspect the wakelock came to your aid because it keeps the memory more active - there may be a delay in starting writes to it as it goes through a retry cycle when powering up the static RAM, which would not exhibit when it remains powered on all the time (that's a conjecture, nothing more).

    Once anything starts showing mmc errors, it's a sign of impending failure unless you see the same behavior across the entire line after a specific update (which means the firmware was probably changed to be too aggressive in power management and/or not patient enough to wait for the memory to be ready for use after power is applied). Given that the Note 4 is approaching the MTBF on static RAM for heavy users, and that not ALL Note 4s exhibit this behavior, I can only say that I suspect your unit's days are numbered, and your clever wakelock trick is buying you time.

    How much? Who can say? Probably not a lot.

    If you depend on this for work or have another critical need for a smartphone, my advice is to upgrade soon. If you can do without a phone for a few days, just make sure everything is being backed up as often as you possibly can and see how much longer you can squeeze out of it. You might be surprised...
    09-06-2017 07:25 AM
  6. natehoy's Avatar
    OP
    Realized I forgot to tag you on this. Please see reply one post above this one.
    09-06-2017 07:40 AM
  7. flyingkytez's Avatar
    I recently bought a used note 4 frim ebay. It was listed that it had problems with resetting and freezing. Indeed it turned out the phone reboots frequently, brining me to a"Downloading... do not turn off target device" Along with that there is a debug console message that says mmc_read failure. Nevertheless after about a hundred tries I managed to reflash the thing (Odin kept failing to write the rom). Still the reboots persisted giving the same mmc errors persist. Sometimes the dubug would says mmc_write fail sometimes it would say mmc_read fail, sometimes both. I then ran into some topics sayin that it's definitely an inherent hardware issue that is pervasive on note 4s. The multimedia controller (mmc) chip seems to fail over time on these. Now this mmc chip manages the flash memory as far as I understand, so if it's failing then the whole 32 gb internal flash would soon become inoperable and I won't be able to boot at all. With all of that said I managed to fix the problem completely. I noticed that the phone only reboots when the screen is off, so I assumed it had something to do with the standby state that the cpu falls into after idling for a while. I simply aquire and hold a partial wakelock on the cpu (there's an app for that) and the phone works flawlessly, never once has it rebooted during this past week and I use the phone heavily everyday. The battery drains a little faster but that's a nonissue.

    Now that's all well and good however I do have some future concerns as to the failing chip. First of all I don't entire understand why the phone works so well even the the memory controller has trouble reading/writing. I save files all the time, download apps, transfer files from pc and never had an error saying that the file can't be written or read nor had I ever had an app crash. So I'm a little confused why that is.

    The second thing is that I'm still not sure I mitigated the issue completely. Will it eventually get worse? Will the phone stor age still degrade over time? If so how long approximately can the phone last in working order with such a condion. Thanks.
    Samsung planned obsolescence.

    https://forums.androidcentral.com/sa...ml#post5964836

    From here on DO NOT do any OTA software update. I had 2 of my friend's Note 4s (hardcore Note 4 fans) phone became corrupted just like yours and it became nearly un-usable after OS update. Install package disabler pro and uninstall the update app.
    09-08-2017 05:59 PM
  8. pr3jker's Avatar
    Try Wake Lock Powermanager, use partial wakelock
    09-09-2017 10:48 AM
  9. pr3jker's Avatar
    Is this the one you mentioned?
    09-09-2017 11:00 AM
  10. Tim Akgayev's Avatar
    I'm the OP, it's now been a while and I just wanted to do a little update. The phone is still working perfectly, that is when it's on and has the Wake lock running. However when the battery drains and the phone is allowed to shutdown, it becomes a nightmare. I use it heavily as my GPS for work and have gotten stuck a few times for hours in the middle of nowhere while I try to reboot the phone, once it reboots it's fine though.

    Just some tips I've learned over time if anyone else has similar issues.

    1) When the phone fails to reboot. Take out the battery and wait exactly 5 min (I mean exactly, if you wait more than 6 or less than 4 then it just won't boot for some reason) then put the batt back in and try booting. If you waited too long or too short, then you have to put the battery back in and just let it sit with the battery inserted for a few minutes, then take out the battery and time exactly 5 min before you reinsert.

    2) I've had times that no matter what I do the phone still won't boot, doesn't charge, doesn't do anything. The first thing is this: even though there are no lights or any activity when you plug in the charger, the battery is still being charged. So if you suspect the battery might be dead, just let it sit in the charger for a while. Once you made sure it sat a whIle with the charger, take out the battery and put both the phone and the battery in the freezer. Leave it in the freezer for about 30 min. Put the battery back in and try to start. It works every time in my case. I think the reason for that is that most likely there is a small crack in the solder joint somewhere in the phone, either the mmc chip itself or in some other part. When frozen the solder contracts and moves a little bit realigning the connection. That's just my guess. By the same logic it's probably also possible the joint doesn't always realign properly even when frozen (although in my case it worked 100% of the times I've done it) so if it doesn't work in your case then maybe try letting the phone warm up and freezing it again.

    Noting the previous, I think the whole mmc issue might possibly be fixed by a reflow (that's when you heat up the motherboard up to about 250 deg C to allow the solder to melt and then reharden, presumably fixing the crack that it might possibly have. I have done a few reflow on my pc motherboard (using a home built reflow station) however I've done those only because I had no other choice, as in my pc wouldn't boot at all. I'm at little hesitan to try it on my phone and risk destroying it. That being said I have replaced a daughter board on this phone about about week ago about had to open it up in the process, the motherboard is incredibly modular and very easy to remove (although do be careful since I ripped two cables that correspond to the back and window buttons on the bottom of the phone while trying to open it, hence the reason it had to replace the daughter board). And about as far as I can tell there no major components that can really melt and its so small that it could easily go under a heat gun, however I'd leave that for the last resort as its something that's got questionabe outcomes.
    01-28-2018 01:22 AM

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