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sanrio alvares 08-25-2012 01:44 AM

Bad: SD card data from phone not seen on PC
Scenario: Add data on SD card from Phone (Click images and save to Card). Access the Card on PC through the Phone the images are not seen. However the images are seen on Phone.
Only after removing the Card and reinserting it in the Phone are the Images seen on the PC. Or rmmoding and modprobing the MMC driver they are visible.
Can anyone help me narrow down on the root cause of this issue?
Any pointers will be much appreciated.

SecretCode 08-26-2012 11:47 AM

What phone? Are you mounting the SD card using the phone's capabilities, or taking it out of the phone and using a separate SD card reader? If you can't see the files in the latter case then something weird is happening (like an encrypted loopback volume perhaps).

sanrio alvares 08-27-2012 01:03 AM

Its a phone running Linux kernel(2.6.31). SD card is mounted using the phone's capabilities. I have tested the same scenario using Card reader too. the images are seen properly. here are the steps
1. insert card in phone.
2. add images to it.
3. access card (thru phone) on PC -> no images seen (Not always but mostly. especially when more than 3 images added at one time)
4. umount card from phone and access through Card Reader -> images are seen properly
5. reinsert card in phone
6. access card on PC -> images are seen

sanrio alvares 08-27-2012 01:18 AM

Does it look like a MMC driver issue? or a USB Mass Storage one? It could also be a media scanning (service) problem. Im unable to narrow down on this.. :(

sanrio alvares 08-27-2012 01:31 AM

One more observation: The above scenario of adding multiple images on card and accessing it on PC works fine the first time it is accessed on PC. Only subsequent additions to SD card give this issue.

SecretCode 08-27-2012 04:04 AM

Intuitively, this looks like another process locking the image files and making them unreadable - or - something on the phone acting as a file server and filtering what can be seen. But neither of these make sense in the context of a USB slave device. (Software on the phone should not be able to access the card at the same time.)

I think it might be related to the MMC driver, yes.

How are you viewing the card? With a file manager app I guess?
Can you see the files with ls -a at the command line?

If you unmount and remount the volume at the command line, do they become visible again?

sanrio alvares 08-27-2012 04:41 AM

When images are added on the card the phone shows the images properly. Accesing the sdcard through command line (via jtag) also shows the images properly.
Unmounting and remounting the card through command line the PC will NOT show the images. only physically reinserting the card in the phone will show the images on the PC.
Are you saying the usb mass storage driver is not the problem here?

SecretCode 08-27-2012 06:07 AM

I'm just trying to help diagnose - it certainly could be something to do with the usb driver.

Maybe someone with more experience of MMC can jump in.

sanrio alvares 08-27-2012 06:33 AM

yes yes i appreciate that. thank you. Im only worried cos after doing multiple tests im still not able to blame a particular module. for eg. MMC driver/USB Mass storage or any other module for that matter. Since it would help me focus on one thing.
Just for my knowledge, are MMC driver, USB Mass Storage and Media scanner service the only modules to be investigated for this problem? or am i missing something here..

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