SD card issue fix - Need testers!

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Hi all,

A few of us on the SD card list thread have tried this and it seems to be stablizing things....the theory as we are working with now is that the problem is due to a power control issue in the Samsung drivers for the phone, not especially in the card itself.

No ill effects have been reported as of yet, and the battery life seems to be on par with before the switch was made. It is a simple fix, and can be reversed easily.

I ran the phone for 2 months without a card, and with these keys toggled, it is actually FASTER than it was. I don't fully believe it, but it has been over a week and rock solid.

First off, you need to dev unlock your phone. See the thread here for simple and complete instructions: http://forum.xda-developers.com/showthread.php?t=938106

Next off, you need to toggle the following 3 registry keys in the Registry Editor provided in the above post:


The keys have to do with MMC (internal memory) power management.The big speed improvements is in games/apps (Fruit Ninja opens and operates leaps and bounds faster than it did when the phone did stock!)

HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>MMC_Class>DisablePowerManagement (Change to 0)

HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>MMC_Class>High_Capacity>DisablePowerManagement (Change to 0)

HKEY_LOCAL_MACHINE>Drivers>SDCARD>ClientDrivers>Class>SDMemory_Class>DisablePowerManagement (Change to 0)

One point of note here, do not be afraid if the phone locks up the first time soft resetting after these changes, mine did and it was fine after a battery pull.

Also, I would be interested to hear any theories about why this one made such a big difference when it seemingly affects only the internal storage. Maybe because the two storage devices are "bridged" by WP7?

Comment below with your experiences please!

If this gets enough test results, we will submit it to Microsoft. Thanks!

As I already mentioned:

Up to now I just did the SD card registry hack. The device is now stable for over 3 days, longer than ever before.

Battery life wasn't noticable affected, lasted for around 40h with moderate usage (thumbs up indeed).

In fact without this registry hack I wasn't able to get down to an empty battery without those reboting/dataloss issues.


But I need some more days, then I will change the MMC registry key also.



No speed improvements mentioned up to now.

I applied the hack to all three keys. So far, it is much less laggy. Not sure if that will return after 4+ weeks as before, but here's a pretty cool side effect:

After the hack, my screen does not stop responding to touch when the phone is placed on my desk or a soft surface, like a couch cushon. It was getting really annoying because I often place mu phone on my desk during the day for easy access, but every time I tried to onlock it, it would not respond unless I picked it up. Sometimes, it's nice to leave it lying down and operate it. Couldn't do that before, but I can now! WooHoo! Thank you for this.

I'll report back if it starts up again in a couple weeks.

Sent from my Focus WP7 using Board Express

Whoa! I just tested this and you are correct! More proof that the Samsung power drivers are full of problems. Who would have thought?

For testing purpose I changed the MMC Keys also and made some Videos (no I won't upload them). There were absoluteley no differences in app loading times (ok, i know the longer loading apps are pretty much all stored on the sd card, ) and also not in overall performance, although this isn't provable easily.

I changed the keys back to normal, but kept the sd card key change to 0.
I address the positive speed effects to sdcard key for now. Perhaps i will make some tests without any reg change in the next few days.

Still stable as hell!


Edit: Damn I forgot to test the not responding problem (even though i didn't notice it that often and badly)

Originally Posted by Sebo1985

For testing purpose I changed the MMC Keys also and made some Videos (no I won't upload them). There were absoluteley no differences in app loading times (ok, i know the longer loading apps are pretty much all stored on the sd card, ) and also not in overall performance, although this isn't provable easily.

I changed the keys back to normal, but kept the sd card key change to 0.
I address the positive speed effects to sdcard key for now. Perhaps i will make some tests without any reg change in the next few days.

Still stable as hell!


Edit: Damn I forgot to test the not responding problem (even though i didn't notice it that often and badly)

As I mentioned above, I'm hoping it's not just a result of resetting something and it still returns in a few weeks. Although, the thing about the screen touch response not working when laying on something is COMPLETELY GONE! That alone is worth the setting change. It really was annoying for me the way I use the phone. Thank you to eveyone involved in finding this setting.

PS: From my perception, I don't believe my battery is behaving any differently. Although, I would imagine if it were scientifically tested, it surely would be using slightly more juice. But it still had the normal amount left in the evening, and I probably used it slightly more testing it out. Maybe getting the screen to perform better uses less power?

For the sake of completeness: I set the sd card key back to 1, and I do not experience any slow down in overall performance or in app loading times. Still I cannot reproduce any of those not responding issues you mentioned.

For today and tomorrow I will stay with this setting an will wait for a random reboot. Let's see what and when it happens.

tried this with a 16gb class2 sandisk... loaded it up to 9.25 left and the reboot monster came... but it was weird... it would rebllt like every 30 sec with no loss then poof all lost...then rendom self reboot all mem would reappear and start the reboot process all over.... now it didnt do this till it was unplugged.... plugged in it was fine... reformatted... re set up did the tweak... loaded and the same as before... so for me no... but im going to test it with another card on the list... heres to hoping....

but it does fix the sitting on the bed and unresponsive gimmick.....

So would this be worthwhile even for someone without an sdcard? For the screen response issue i mean. It's so annoying haha.



edit: Screw it i went ahead and did it hah. It def fixed the touch screen responsiveness issue!

Which cards?

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Can you guys post the specific SD cards you are testing this with. I am curious to see if somebody has tested it with the Sandisk class 2 32gb card. Thanks.